Digital Camera Patent AbstractA digital camera includes an image control processing section in
which a memory controller controls a video memory, a bus arbitrator,
a display sequencer, and a timing adjusting section. Image data
are read out of the video memory and fed to a data corrector. The
display sequencer adjusts a sampling order in accordance with the
combination of luminance data and color data constituting the image
data, while varying a packet size. The bus arbitrator arbitrates
access requests in accordance with priority to thereby reduce the
occupation ratio of a bus. The data corrector restores and processes
the image data and then delivers them to a buffer memory included
in the timing adjusting section.
Digital Camera Patent ClaimsWhat is claimed is:
1. An image control device for controlling input image data, executing
signal processing with controlled image data, and outputting processed
image data in accordance with a preselected standard, said device
comprising: a memory for storing the input image data; a standard
adjusting circuit for storing the image data read out of said memory
therein and outputting stored image data at a timing matching with
the preselected standard; a memory control circuit for controlling
at least said memory and said standard adjusting circuit, said memory
control circuit controlling input and output of the image data from
said memory, setting a unit amount of continuous image data to be
handled together at the time of output, setting a unit number of
image data for a single line and consisting of unit amounts of continuous
image data, and outputting a request for an access to said memory
to thereby control read-out; a communicating circuit for selectively
sending or receiving the image data; an image correcting circuit
for analyzing, when the image data read out of said memory are smaller
in amount than the unit number of image data, particular information
particular to said image data and relating to display, and executing,
based on a result of analysis, at least one of restoration and processing
with each unit image data of divided image data; an instruction
information feeding circuit for encoding the particular information
and feeding encoded particular information to said image correcting
circuit; a display adjusting circuit for adjusting, based on a condition
input in accordance with a combination of luminance data and color
data constituting the image data read out of said memory, a sampling
order and controlling feed of the unit number of image data; and
an arbitrating circuit for giving the highest degree of priority
to an access for refreshing said memory, and arbitrating an access
request for control data, which differs from the image data, with
respect to a remaining accessible time when said image data are
output, wherein said display adjusting circuit comprising a size
controlling circuit for controlling, when supplied with valid pixel
number information representative of a number of pixels to be actually
used for display and independent of a data size whose unit is the
unit amount of image data, output of image data short of the unit
number of image data on the basis of said number of pixels or controlling,
based on said data size, delivery of said unit number of image data
on a single line, and delivering controlled image data to said memory,
wherein said communicating circuit comprises an interface for interchanging
the image data with a unit located outside of said device, and wherein
said image correcting circuit and said instruction information feeding
circuit precede said standard adjusting circuit.
2. The device in accordance with claim 1, wherein said communicating
circuit communicates via an extended bus width or an additional
exclusive line assigned to the particular information as well as
to data and operation control.
3. The device in accordance with claim 2, wherein said size controlling
circuit comprises: a header analyzing circuit for analyzing header
information included in the image data; and a size resetting circuit
for resetting, in accordance with a result of analysis output from
said header analyzing circuit, a data size of the unit amount of
image data by which the image data are divided, and dividing said
image data by a reset data size.
4. The device in accordance with claim 3, wherein said size resetting
circuit comprises a small-division function block for making, a
size of a division of the image data smaller than a usual size when
the result of analysis of the header information shows that a preselected
image pattern should be repeated to form a display area; a large-size
function block for making the size of the division larger than the
usual size when the result of analysis shows that a thumbnail image
should be displayed; and an optimal division function block for
calculating, when the result of analysis shows a size different
in the division of image data from repetition of the preselected
pattern, the thumbnail image and the usual size, a size that optimally
divides the image data, and again dividing said image data by a
calculated size.
5. The device in accordance with claim 4, wherein said small-size
function block executes at least one of feed of the preselected
image pattern and indication of said feed, calculates a number of
times of repetition, and delivers image data representative of said
preselected image pattern.
6. The device in accordance with claim 5, further comprising: a
source voltage detecting circuit for detecting a voltage of a power
source that drives said device; and a system control circuit for
controlling at least said memory controller and said image correcting
circuit when the voltage output from said source voltage detecting
circuit is lower than a preselected reference voltage.
7. The device in accordance with claim 6, wherein said system control
circuit controls a frequency of a clock signal output from said
standard adjusting circuit.
8. The device in accordance with claim 2, wherein said image correcting
circuit comprises a storage for storing beforehand the particular
information or data for replacement for each divided image data
to be handled together.
9. The device in accordance with clam 2, wherein said image correcting
circuit comprises: an instruction analyzing circuit for separating
and analyzing a content of the particular information and outputting
a plurality of kinds of analyzed instruction information as a control
signal; a restoration adjusting circuit for restoring the image
data to a preselected data size in accordance with, among the instruction
information included in the control signal, first information representative
of a data size of said image data; a data copying circuit for repeatedly
copying, based on second information independent of the data size
and representative of the valid number of pixels as one of the instruction
information, the image data a number of times derived from a leading
one of the addresses included in the control signal; a data selecting
circuit for selecting, based on at least one of the second information
and third information independent of the data size and indicative
of a leading address for writing image data, one of the preselected
region of the image data, said image data and data of the instruction
information and outputs said preselected region, said image data
or said data to said standard adjusting circuit; an aperture generating
circuit for generating an aperture component in accordance with
fourth information independent of the data size and representative
of sharpness particular to each of divided image data to be handled
together; an adding circuit for adding the aperture component to
the image data; a signal correcting circuit for executing, based
on fifth information independent of the data size and representative
of at least one of lightness, contract, a noise level and special
effect processing particular to each divided image data to be handled
together; and a zoom correcting circuit for executing electronic
zoom processing each divided image data in accordance with sixth
information independent of the data size and representative of an
electronic zoom magnification particular to each divided image data
to be handled together.
10. An image control device for controlling input image data, executing
signal processing with controlled image data, and outputting processed
image data in accordance with a preselected standard, said device
comprising: a memory for storing the input image data; a standard
adjusting circuit for storing the image data read out of said memory
therein and outputting stored image data at a timing matching with
the preselected standard; a memory control circuit for controlling
at least said memory and said standard adjusting circuit, said memory
control circuit controlling input and output of the image data from
said memory, setting a unit amount of continuous image data to be
handled together at the time of output, setting a unit number of
image data for a single line and consisting of unit amounts of continuous
image data, and outputting a request for an access to said memory
to thereby control read-out; a communicating circuit for selectively
sending or receiving the image data; an image correcting circuit
for analyzing, when the image data read out of said memory are smaller
in amount than the unit number of image data, particular information
particular to said image data and relating to display, and executing,
based on a result of analysis, at least one of restoration and processing
with each unit image data of divided image data; and an instruction
information feeding circuit for encoding the particular information
and feeding encoded particular information to said image correcting
circuit, wherein said image correcting circuit and said instruction
information feeding circuit precede said standard adjusting circuit,
wherein said image correcting circuit comprises: an instruction
analyzing circuit for separating and analyzing a content of the
particular information as the instruction information and outputting
a control signal representative of a result of analysis of said
instruction information; and a restoration adjusting circuit for
restoring the image data to a preselected data size in accordance
with, among the instruction information included in the control
signal, first information representative of a data size of said
image data.
11. The device in accordance with claim 10, wherein said instruction
analyzing circuit separates, among the particular information, second
information independent of the data size and representative of the
valid number of pixels as one of the instruction information, divides
said data size by said second information, determines the image
data corresponding to a resulting quotient, determines a leading
address of a destination on the basis of said instruction information,
selecting a reciprocal multiple of said quotient as a number of
times of copying, and outputs said image data corresponding to said
quotient, said leading address, and said number of times of copying
as the control signal, and said image correcting circuit further
comprises a data copying circuit for copying the image data, a leading
address being first, the number of times of copying while matching
addresses included in the control signal to said image data.
12. The device in accordance with claim 11, wherein said data copying
circuit repeatedly outputs, based on the second information, the
image data read out of a preselected area of said memory or data
read out of a register, which stores the instruction information,
the number of times of copying.
13. The device in accordance with claim 10, wherein said instruction
analyzing circuit separates and analyzes, among the particular information,
third information independent of the data size and indicative of
a leading address for writing image data in any position of said
standard adjusting circuit, and delivers analyzed instruction information
to said standard adjusting circuit as the control signal, and said
image correcting circuit further comprises a data selecting circuit
for selecting, based on at least one of the second information,
independent of the data size and representative of the valid number
of pixels as one of the instruction information, and the third information,
one of the preselected region of the image data, said image data
and data of the instruction information and outputs said preselected
area, said image data or said data to said standard adjusting circuit.
14. The device in accordance with claim 13, wherein said data selecting
circuit outputs, based on the third information, the image data
of the preselected area or pattern data representative of a preselected
pattern and indicated by the instruction information in a position
different from the image data in accordance with the leading address.
15. The device in accordance with claim 10, wherein said instruction
analyzing circuit separates and analyzes, among the particular information,
fourth information independent of the data size and representative
of sharpness particular to each of divided image data to be handled
together, and outputs analyzed instruction information as the control
signal, and said image correcting circuit further comprises: an
aperture generating circuit for generating an aperture component;
and an adding circuit for adding the aperture component to the divided
image data.
16. The device in accordance with claim 15, wherein said aperture
generating circuit comprises an aperture adjusting block for varying
the sharpness of each divided image data in accordance with the
forth information.
17. The device in accordance with claim 10, wherein said instruction
analyzing circuit separates and analyzes, among the particular information,
fifth information independent of the data size and representative
of at least one of lightness, contract, a noise level and special
effect processing particular to each divided image data to be handled
together, and outputs analyzed instruction information as the control
signal, and said image correcting circuit further comprises a signal
correcting circuit for executing, based on the fifth information,
at least one of lightness or contrast improvement, noise reduction
and special effect processing with each divided image data.
18. The device in accordance with claim 17, wherein said signal
correcting circuit comprises: a calculating circuit for varying,
based on the fifth information, at least one of the lightness, contrast
and noise level of each divided image data; and a filtering circuit
for executing, based on the fifth information, the special effect
processing with each divided image data and varying a frequency
characteristic of said divided image data.
19. The device in accordance with claim 10, wherein said instruction
analyzing circuit separates and analyzes, among the particular information,
sixth information independent of the data size and representative
of an electronic zoom magnification particular to each divided image
data to be handled together and outputs analyzed instruction information
as the control signal, and said image correcting circuit further
comprises a zoom correcting circuit for executing electronic zoom
processing particular to each divided image data in accordance with
the sixth information.
20. The device in accordance with claim 19, wherein said zoom correcting
circuit executes, based on the sixth information, distortion correction
with each divided image data for compensating for distortion of
optics.
21. The device in accordance with claim 10, further comprising:
a source voltage detecting circuit for detecting a voltage of a
power source that drives said device; and a system control circuit
for controlling at least said memory controller and said image correcting
circuit when the voltage output from said source voltage detecting
circuit is lower than a preselected reference voltage.
22. The device in accordance with claim 21, wherein said system
control circuit controls a frequency of a clock signal output from
said standard adjusting circuit.
23. A digital camera for focusing incident light representative
of a scene on optics, picking up said incident light by photoelectric
transduction, converting resulting signal charges to a digital signal
to thereby output raw image data, executing matrix processing with
said raw image data to thereby produce dot-sequential image data
consisting of luminance data and color data, compressing or expanding
said image data, writing compressed image data in a recording medium
or reading said compressed data out of said recording medium, said
digital camera comprising: a memory for storing the input image
data; a standard adjusting circuit for storing the image data read
out of said memory therein and outputting stored image data at a
timing matching with the preselected standard; a memory control
circuit for controlling at least said memory and said standard adjusting
circuit, said memory control circuit controlling input and output
of the image data from said memory, setting a unit amount of continuous
image data to be handled together at the time of output, setting
a unit number of image data for a single line and consisting of
unit amounts of continuous image data, and outputting a request
for an access to said memory to thereby control read-out; a communicating
circuit for selectively sending or receiving the image data; an
image correcting circuit for analyzing, when the image data read
out of said memory are smaller in amount than the unit number of
image data, particular information particular to said image data
and relating to display, and executing, based on a result of analysis,
at least one of restoration and processing with each unit image
data of divided image data; an instruction information feeding circuit
for encoding the particular information and feeding encoded particular
information to said image correcting circuit; a display adjusting
circuit for adjusting, based on a condition input in accordance
with a combination of luminance data and color data constituting
the image data read out of said memory, a sampling order and controlling
feed of the unit number of image data; and an arbitrating circuit
for giving the highest degree of priority to an access for refreshing
said memory, and arbitrating an access request for control data,
which differs from the image data, with respect to a remaining accessible
time when said image data are output, wherein said display adjusting
circuit comprising a size controlling circuit for controlling, when
supplied with valid pixel number information representative of a
number of pixels to be actually used for display and independent
of a data size whose unit is the unit amount of image data, output
of image data short of the unit number of image data on the basis
of said number of pixels or controlling, based on said data size,
delivery of said unit number of image data on a single line, and
delivering controlled image data to said memory, wherein said image
correcting circuit and said instruction information feeding circuit
precede said standard adjusting circuit, and wherein said communicating
circuit comprises an interface for interchanging the image data
with a unit located outside of said device.
24. The camera in accordance with claim 23, wherein said communicating
circuit communicates via an extended bus width or an additional
exclusive line assigned to the particular information as well as
to data and operation control.
25. The camera in accordance with claim 24, wherein said size controlling
circuit comprises: a header analyzing circuit for analyzing header
information included in the image data; and a size resetting circuit
for resetting, in accordance with a result of analysis output from
said header analyzing circuit, a data size of the unit amount of
image data by which the image data are divided, and dividing said
image data by a reset data size.
26. The camera in accordance with claim 25, wherein said size resetting
circuit comprises a small-division function block for making, a
size of a division of the image data smaller than a usual size when
the result of analysis of the header information shows that a preselected
image pattern should be repeated to form a display area; a large-size
function block for making the size of the division larger than the
usual size when the result of analysis shows that a thumbnail image
should be displayed; and an optimal division function block for
calculating, when the result of analysis shows a size different
in the division of image data from repetition of the preselected
pattern, the thumbnail image and the usual size, a size that optimally
divides the image data, and again dividing said image data by a
calculated size.
27. The camera in accordance with claim 26, wherein said small-size
function block executes at least one of feed of the preselected
image pattern and indication of said feed, calculates a number of
times of repetition, and delivers image data representative of said
preselected image pattern.
28. The camera in accordance with claim 27, further comprising:
a source voltage detecting circuit for detecting a voltage of a
power source that drives said device; and a system control circuit
for controlling at least said memory controller and said image correcting
circuit when the voltage output from said source voltage detecting
circuit is lower than a preselected reference voltage.
29. The camera in accordance with claim 24, wherein said image
correcting circuit comprises a storage for storing beforehand the
particular information or data for replacement for each divided
image data to be handled together.
30. The camera in accordance with clam 24, wherein said image correcting
circuit comprises: an instruction analyzing circuit for separating
and analyzing a content of the particular information and outputting
a plurality of kinds of analyzed instruction information as a control
signal; a restoration adjusting circuit for restoring the image
data to a preselected data size in accordance with, among the instruction
information included in the control signal, first information representative
of a data size of said image data; a data copying circuit for repeatedly
copying, based on second information independent of the data size
and representative of the valid number of pixels as one of the instruction
information, the image data a number of times derived from a leading
one of the addresses included in the control signal; a data selecting
circuit for selecting, based on at least one of the second information
and third information independent of the data size and indicative
of a leading address for writing image data, one of the preselected
region of the image data, said image data and data of the instruction
information and outputs said preselected region, said image data
or said data to said standard adjusting circuit; an aperture generating
circuit for generating an aperture component in accordance with
fourth information independent of the data size and representative
of sharpness particular to each of divided image data to be handled
together; an adding circuit for adding the aperture component to
the image data; a signal correcting circuit for executing, based
on fifth information independent of the data size and representative
of at least one of lightness, contract, a noise level and special
effect processing particular to each divided image data to be handled
together; and a zoom correcting circuit for executing electronic
zoom processing each divided image data in accordance with sixth
information independent of the data size and representative of an
electronic zoom magnification particular to each divided image data
to be handled together.
31. A digital camera for focusing incident light representative
of a scene on optics, picking up said incident light by photoelectric
transduction, converting resulting signal charges to a digital signal
to thereby output raw image data, executing matrix processing with
said raw image data to thereby produce dot-sequential image data
consisting of luminance data and color data, compressing or expanding
said image data, writing compressed image data in a recording medium
or reading said compressed data out of said recording medium, said
digital camera comprising: a memory for storing the input image
data; a standard adjusting circuit for storing the image data read
out of said memory therein and outputting stored image data at a
timing matching with the preselected standard; a memory control
circuit for controlling at least said memory and said standard adjusting
circuit, said memory control circuit controlling input and output
of the image data from said memory, setting a unit amount of continuous
image data to be handled together at the time of output, setting
a unit number of image data for a single line and consisting of
unit amounts of continuous image data, and outputting a request
for an access to said memory to thereby control read-out; a communicating
circuit for selectively sending or receiving the image data; an
image correcting circuit for analyzing, when the image data read
out of said memory are smaller in amount than the unit number of
image data, particular information particular to said image data
and relating to display, and executing, based on a result of analysis,
at least one of restoration and processing with each unit image
data of divided image data; and an instruction information feeding
circuit for encoding the particular information and feeding encoded
particular information to said image correcting circuit, wherein
said image correcting circuit and said instruction information feeding
circuit precede said standard adjusting circuit, wherein said image
correcting circuit comprises: an instruction analyzing circuit for
separating and analyzing a content of the particular information
as the instruction information and outputting a control signal representative
of a result of analysis of said instruction information; and a restoration
adjusting circuit for restoring the image data to a preselected
data size in accordance with, among the instruction information
included in the control signal, first information representative
of a data size of said image data.
32. The camera in accordance with claim 31, wherein said instruction
analyzing circuit separates, among the particular information, second
information independent of the data size and representative of the
valid number of pixels as one of the instruction information, divides
said data size by said second information, determines the image
data corresponding to a resulting quotient, determines a leading
address of a destination on the basis of said instruction information,
selecting a reciprocal multiple of said quotient as a number of
times of copying, and outputs said image data corresponding to said
quotient, said leading address, and said number of times of copying
as the control signal, and said image correcting circuit further
comprises a data copying circuit for copying the image data, a leading
address being first, the number of times of copying while matching
addresses included in the control signal to said image data.
33. The camera in accordance with claim 32, wherein said data copying
circuit repeatedly outputs, based on the second information, the
image data read out of a preselected area of said memory or data
read out of a register, which stores the instruction information,
the number of times of copying.
34. The camera in accordance with claim 31, wherein said instruction
analyzing circuit separates and analyzes, among the particular information,
third information independent of the data size and indicative of
a leading address for writing image data in any position of said
standard adjusting circuit, and delivers analyzed instruction information
to said standard adjusting circuit as the control signal, and said
image correcting circuit further comprises a data selecting circuit
for selecting, based on at least one of the second information,
independent of the data size and representative of the valid number
of pixels as one of the instruction information, and the third information,
one of the preselected region of the image data, said image data
and data of the instruction information and outputs said preselected
area, said image data or said data to said standard adjusting circuit.
35. The camera in accordance with claim 34, wherein said data selecting
circuit outputs, based on the third information, the image data
of the preselected area or pattern data representative of a preselected
pattern and indicated by the instruction information in a position
different from the image data in accordance with the leading address.
36. The camera in accordance with claim 31, wherein said instruction
analyzing circuit separates and analyzes, among the particular information,
fourth information independent of the data size and representative
of sharpness particular to each of divided image data to be handled
together, and outputs analyzed instruction information as the control
signal, and said image correcting circuit further comprises: an
aperture generating circuit for generating an aperture component;
and an adding circuit for adding the aperture component to the divided
image data.
37. The camera in accordance with claim 36, wherein said aperture
generating circuit comprises an aperture adjusting block for varying
the sharpness of each divided image data in accordance with the
forth information.
38. The camera in accordance with claim 31, wherein said instruction
analyzing circuit separates and analyzes, among the particular information,
fifth information independent of the data size and representative
of at least one of lightness, contract, a noise level and special
effect processing particular to each divided image data to be handled
together, and outputs analyzed instruction information as the control
signal, and said image correcting circuit further comprises a signal
correcting circuit for executing, based on the fifth information,
at least one of lightness or contrast improvement, noise reduction
and special effect processing with each divided image data.
39. The camera in accordance with claim 38, wherein said signal
correcting circuit comprises: a calculating circuit for varying,
based on the fifth information, at least one of the lightness, contrast
and noise level of each divided image data; and a filtering circuit
for executing, based on the fifth information, the special effect
processing with each divided image data and varying a frequency
characteristic of said divided image data.
40. The camera in accordance with claim 31, wherein said instruction
analyzing circuit separates and analyzes, among the particular information,
sixth information independent of the data size and representative
of an electronic zoom magnification particular to each divided image
data to be handled together and outputs analyzed instruction information
as the control signal, and said image correcting circuit further
comprises a zoom correcting circuit for executing electronic zoom
processing particular to each divided image data in accordance with
the sixth information.
41. The camera in accordance with claim 40, wherein said zoom correcting
circuit executes, based on the sixth information, distortion correction
with each divided image data for compensating for distortion of
optics.
42. The camera in accordance with claim 31, further comprising:
a source voltage detecting circuit for detecting a voltage of a
power source that drives said device; and a system control circuit
for controlling at least said memory controller and said image correcting
circuit when the voltage output from said source voltage detecting
circuit is lower than a preselected reference voltage.
43. The camera in accordance with claim 42, wherein said system
control circuit controls a frequency of a clock signal output from
said standard adjusting circuit.
44. An image control device for controlling input image data, executing
signal processing with controlled image data, and outputting processed
image data in accordance with a preselected standard, said device
comprising: a memory for storing the input image data; a standard
adjusting circuit for storing the image data read out of said memory
therein and outputting stored image data at a timing matching with
the preselected standard; a memory control circuit for controlling
at least said memory and said standard adjusting circuit, said memory
control circuit controlling input and output of the image data from
said memory, setting a unit amount of continuous image data to be
handled together at the time of output, setting a unit number of
image data for a single line and consisting of unit amounts of continuous
image data, and outputting a request for an access to said memory
to thereby control read-out; a communicating circuit for selectively
sending Or receiving the image data; an image correcting circuit
for analyzing, when the image data read out of said memory are smaller
in amount than the unit number of image data, particular information
particular to said image data and relating to display, and executing,
based on a result of analysis, at least one of restoration and processing
with each unit image data of divided image data; and an instruction
information feeding circuit for encoding the particular information
and feeding encoded particular information to said image correcting
circuit, wherein said image correcting circuit and said instruction
information feeding circuit precede said standard adjusting circuit,
and wherein said image correcting circuit comprises an arbitrating
circuit for giving the highest degree of priority to an access for
refreshing said memory, and arbitrating an access request for control
data, which differs from the image data, with respect to a remaining
accessible time when said image data are output. Digital Camera Patent DescriptionBACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image control device feasible
for a display, a digital camera, a printer or similar apparatus
having at least one of an image data displaying function, an image
data reproducing function and an image data printing function as
well as to an image control method and a digital camera.
2. Description of the Background Art
It is a common practice in the imaging art to read out image data
stored in a frame memory and display them on a TV (television) set
or similar display. However, it has been difficult to rewrite the
image data of the frame memory during image display period due to
disturbance to the image ascribable to noise and limited available
time. In light of this, an arrangement is generally made such that
a CPU (Central Processing Unit) accesses the frame memory during
blanking period particular to broadcast standards in order to rewrite
the image data. This arrangement, however, brings about a problem
that the mean access rate of the CPU to the frame memory is extremely
low when an image is displayed.
In order to solve the above problem, use may be made of a FIFO
(First-In First-Out) memory or similar buffer memory, as proposed
in the past. Data are transferred to the buffer memory at a rate
higher than the clock rate of a TV signal, so that the remaining
time is available for rewriting the data stored in the frame memory.
Generally, the buffer memory has a capacity exceeding the number
of pixels of an image in the horizontal direction. The data temporarily
stored in the buffer memory are read out at the clock rate of the
TV signal. This guarantees a period of time for the CPU to access
the frame memory even during periods other than the blanking period.
However, even the buffer memory scheme prevents the CPU from accessing
the frame memory during the transfer of one line of image data from
the frame memory to the buffer memory. The waiting time of the CPU
is wasteful because the clock rate for the data transfer from the
frame memory to the buffer memory is several times as high as the
clock rate of the TV signal.
On the other hand, an image display system often includes an electronic
zooming function. Y data representative of luminance and C.sub.R
and C.sub.B data representative of pairs of colors are written to
the frame memory in a 4:2:2 dot-sequential format. In this case,
a conventional, electronic zoom circuit lowers image quality because
the sampled C.sub.R and C.sub.B pairs are disturbed because of addresses,
depending on magnification. To avoid the disturbance to the C.sub.R
and C.sub.B pairs, it has been customary to again sample the C.sub.R
and C.sub.B data for causing them to coincide, restore the Y, C.sub.R
and C.sub.B data to a 4:4:4 format, and then execute zooming.
The applicant has proposed an implementation for enhancing the
performance of the entire system. The implementation reduces the
waiting time of a CPU output an access request without regard to
a position or time in a one-line display period, i.e., implements
rapid response to the access request. Besides the enhanced performance
of the entire system, there is an increasing demand for more advanced
functions. Advanced functions, however, aggravate power consumption
and must therefore be accompanied by power saving arrangements.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an image control
device capable of further enhancing the performance of the entire
system while reducing power consumption, an image control method,
and a digital camera.
In accordance with the present invention, an image control device
controls input image data, executes signal processing with the controlled
image data, and outputs the processed image data in accordance with
a preselected standard. The device includes a memory for storing
the input image data. A standard adjusting circuit stores the image
data read out of the memory therein and outputs stored image data
at a timing matching with the preselected standard. A memory control
circuit controls at least the memory and standard adjusting circuit.
The memory control circuit controls the input and output of the
image data from the memory, sets a unit amount of continuous image
data to be handled together at the time of output, sets a unit number
of image data for a single line and consisting of the unit amounts
of continuous image data, and outputs a request for an access to
the memory to thereby control read-out. A communicating circuit
selectively sends or receives the image data. An image correcting
circuit analyzes, when the image data read out of the memory are
smaller in amount than the unit number of image data, particular
information particular to the image data and relating to display
and executes, based on the result of analysis, at least one of restoration
and processing with each unit image data of divided image data.
An instruction information feeding circuit encodes the particular
information and then feeds it to the image correcting circuit. The
image correcting circuit and instruction information feeding circuit
precede the standard adjusting circuit.
The image control method described above may be implemented as
a digital camera.
Also, in accordance with the present invention, a control method
for an image control device processes divided image data to be handled
together each consisting of a luminance component and a color component
to thereby produce adjusted divided image data in which the luminance
component and color component are corrected as to deviation in sampling.
The method then outputs the adjusted divided image data in accordance
with a preselected standard. The method begins with a fist step
of adjusting the separation of the luminance component and the color
component, the division of image data and the correction of the
deviation in sampling, varying, based on particular information
particular to the image data, the data size of the adjusted divided
image data to a different data size, and outputting the adjusted
divided image data to a bus while executing arbitration. A second
step corrects each of the adjusted divided image data in accordance
with instruction information showing how at least one of a plurality
of kinds of processing and restoration should be executed. A third
step selects and latches the adjusted divided image data output
by the second step and selects and reads out one of a plurality
of latched, adjusted divided image data as part of a picture.
In accordance with the present invention, a digital camera controls
input image data, executes signal processing with the controlled
image data, and outputs the processed image data in accordance with
a preselected standard. The device includes a memory for storing
the input image data. A standard adjusting circuit stores the image
data read out of the memory therein and outputs stored image data
at a timing matching with the preselected standard. A memory control
circuit controls at least the memory and standard adjusting circuit.
The memory control circuit controls the input and output of the
image data from the memory, sets a unit amount of continuous image
data to be handled together at the time of output, sets a unit number
of image data for a single line and consisting of the unit amounts
of continuous image data, and outputs a request for an access to
the memory to thereby control read-out. A communicating circuit
selectively sends or receives the image data. An image correcting
circuit analyzes, when the image data read out of the memory are
smaller in amount than the unit number of image data, particular
information particular to the image data and relating to display
and executes, based on the result of analysis, at least one of restoration
and processing with each unit image data of divided image data.
An instruction information feeding circuit encodes the particular
information and then feeds it to the image correcting circuit. The
image correcting circuit and instruction information feeding circuit
precede the standard adjusting circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
The objects and features of the present invention will become more
apparent from consideration of the following detailed description
taken in conjunction with the accompanying drawings in which:
FIG. 1 shows how FIGS. 1A and 1B are combined;
FIGS. 1A and 1B are schematic block diagrams showing a digital
camera to which an image control device embodying the present invention
is applied;
FIG. 2 is a schematic block diagram showing functions available
with a memory controller shown in FIG. 1B;
FIG. 3 is a schematic block diagram showing a specific configuration
of a display sequencer shown in FIG. 1A;
FIG. 4 is a schematic block diagram showing a specific configuration
of a data corrector shown in FIG. 1B;
FIG. 5 is a schematic block diagram showing a specific configuration
of a buffer memory shown in FIG. 1B;
FIG. 6 shows some different sampling systems applicable to luminance
data and two different color data that constitute image data in
combination;
FIG. 7 is a timing chart demonstrating a procedure for maintaining
the luminance data and color data sampled by a 4:2:2 .times.1 or
equi-scale processing in pairs;
FIG. 8 is a timing chart demonstrating a procedure for maintaining
the luminance data and color data sampled by a 4:2:2 zoom processing
in pairs, an even address heading the data;
FIG. 9 is a timing chart demonstrating a procedure for maintaining
the luminance data and color data sampled by a 4:2:2 zoom processing
in pairs, an odd address heading the data;
FIG. 10 is a timing chart showing a relation between consecutive
packets transferred in a single line in an image control processing
section shown in FIGS. 1A and 1B;
FIG. 11 is a flowchart representative of a main routine that the
illustrative embodiment executes;
FIGS. 12A and 12B are flowcharts showing a subroutine SUB1 included
in the main routine specifically;
FIG. 13 is a flowchart showing the rest of the subroutine SUB1;
FIG. 14 is a flowchart representative of a subroutine SUB3 shown
in FIG. 12A;
FIG. 15 is a flowchart showing the rest of the subroutine SUB3;
FIG. 16 is a flowchart representative of a subroutine SUB4 shown
in FIG. 14;
FIGS. 17 through 20 are flowcharts showing the rest of the subroutine
SUB4;
FIG. 21 is a flowchart representative of a subroutine SUB5 shown
in FIG. 14;
FIG. 22 is a flowchart showing the rest of the subroutine SUB 5;
FIG. 23 is a flowchart representative of a subroutine SUB6 shown
in FIG. 15;
FIG. 24 is a timing chart showing a relation between packets transferred
on one line, a packet size and the number of packets transferred;
FIG. 25 is a flowchart demonstrating a subroutine SUB2 included
in the main routine in detail;
FIG. 26 is a flowchart showing the rest of the subroutine SUB2;
FIG. 27 shows a specific picture displayed by the illustrative
embodiment; and
FIG. 28 is a schematic block diagram showing an alternative embodiment
of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1A and 1B, an image control device embodying
the present invention is shown and applied to a digital camera.
As shown, the digital camera, generally 10, includes a lens system
10A, a driver 10B, a TG (Timing signal Generator) 10c, an image
pickup 10d, a preprocessor 10e, signal processor 10f, a storage
10g, and an image control processing section 10h. Constituents not
relevant to the understanding of the present invention are not shown
in FIGS. 1A and 1B and will not be described specifically. Signals
are designated by reference numerals attached to connect lines on
which they appear.
As shown in FIG. 1A, the lens system 10A is made up of, e.g., a
plurality of optical lenses not shown. The lens system 10A includes
a zoom mechanism and an AF (Automatic Focus) mechanism although
not shown specifically. The zoom mechanism controls the positions
of the lenses and therefore a view angle in accordance with a signal
output from an operation panel not shown. The AF mechanism automatically
focuses the camera 10 on a desired subject in accordance with a
distance between the camera 10 and the subject. More specifically,
as shown in FIG. 28, a signal 140 output from the operation panel
is input to a system controller 10j, as will be described specifically
later. A driver 10B feeds a plurality of different drive signals
to the lens system 10A although not shown specifically.
The driver 10B includes a V (vertical) driver, a discard signal
generating circuit and a transfer signal generating circuit although
not shown specifically. The TG 10c feeds various timing signals
to the driver 10B. In a usual exposure mode, the V driver generates
a trilevel signal, i.e., a high (H), a medium (M) or a low (L) level
signal for the vertical transfer of signal charges. Also, the V
driver feeds a bias voltage to each device that should perform photoelectric
transduction. The TG 10c delivers timing signals including field
shift gate pulses to the image pickup 10d via the V driver as signals
relating to vertical drive. The discard signal generating circuit
feeds a discard signal to the image pickup 10d in order to release
needless signal charges to a circuit board via reset drains and
overflow drains, as needed.
The transfer signal generating circuit generates a vertical transfer
signal V, a horizontal transfer signal H and a reset pulse R as
transfer signals. The image pickup 10d includes a solid-state image
sensor 101C in which transfer registers are formed. The transfer
signal generating circuit sequentially executes the field shift
of signal charges stored in the devices of the image sensor 101C
to the transfer registers, the transfer of the signal charges within
the transfer registers based on multiphase drive, and the line shift
of the signal charges. Also, the transfer signal generating circuit
discards the signal charges stored in the devices of the image sensor
101C at a preselected timing by feeding reset pulses. In this manner,
the image pickup 10d operates in accordance with the timing signals
and drive signals output from the TG 10c and driver 10B, respectively.
The TG 10c delivers particular timing signals to each of the preprocessor
10e and signal processor 10f as well.
The operation panel includes a shutter release button and a function
for allowing the operator of the camera 10 to select a desired item
on a monitor, although not shown specifically. The shutter release
button has two stepwise positions, i.e., a half-stroke position
S1 and a full-deep position S2. When the operator pushes the shutter
release button to the half-stroke position S1 or the full-stroke
position S2, the camera 10 operates in a preparatory mode or a camera
mode, respectively. The operation panel informs the system controller
10j of the mode set up by sending the signal 140 (see FIG. 28).
In the preparatory mode, the system controller 10j executes AF
drive control with the lens system 10A. Specifically, the system
controller 10j determines, based on the input signal 140, a direction
in which the lenses of the lens system 10A should be shifted in
accordance with focus servo control. The system controller 10j then
feeds a control signal to an AF drive controller, not shown, in
order to shift the lenses of the lens system 10A in the above direction.
The AF drive controller feeds a drive signal based on the control
signal to a shifting mechanism associated with the lens system 10A.
As a result, the lens system 10A is shifted to an optimal focal
position.
Further, in the preparatory mode, the system controller 10j feeds
to an AE (Automatic Exposure) controller, not shown, control signals
and data representative of a lens opening and a shutter speed (exposure
time) based on an estimated AE value. The AE controller outputs
drive signals in accordance with the control signals and data that
are meant for an iris mechanism and a mechanical shutter, not shown.
As for the estimated AE value, a signal charge is read out of each
of a plurality of portions or a center portion of the image pickup
10d as a photometry signal. The photometry signal is fed to the
signal processor 10f via the preprocessor 10e. The signal processor
10f processes an input digital signal in accordance with the photometry
signal.
The image pickup 10d includes an optical low-pass filter 101a and
a color filter 101b in addition to the image sensor 10c. The optical
low-pass filter 101a limits the spatial frequency of incident light
to below the Nyquist frequency. The color filter 101b has color
filter segments of three primary colors R (red), G (green) and B
(blue) arranged in a preselected pattern. The color filter segments
each face a particular photosensitive cell of the image sensor 101c.
The arrangement of the color filter 101b is therefore dependent
on the arrangement of the photosensitive cells of the image sensor
10c. For example, when the photosensitive cells are arranged in
a honeycomb pattern by being shifted by a single pixel from each
other, the color filter segments may be arranged in a G square,
RB full-checker pattern. If desired, the R, G and B filter segments
may be replaced with filter segments of complementary colors, in
which case conversion of complementary colors to primary colors
will be executed in a signal processing stage to follow.
The image sensor 101c may be implemented as a CCD (Charge Coupled
Device) image sensor or a MOS (Metal Oxide Semiconductor) image
sensor. In the illustrative embodiment, the image sensor 101c is
implemented as a CCD image sensor and converts incident light to
signal charges. In the image sensor 101c, the photosensitive cells
are bidimensionally arranged in vertical and horizontal arrays while
being spaced from each other by a pitch corresponding to a pixel
pitch. More specifically, in the honeycomb pattern, nearby photosensitive
cells are shifted from each other by half a pitch in the vertical
and horizontal directions. As for the honeycomb pattern, vertical
transfer registers for vertically transferring signal charges are
formed in, e.g., a zigzag configuration so as to skirt round nearby
photosensitive cells.
The image sensor 101c additionally includes horizontal transfer
registers arranged in an array perpendicular to the arrays of vertical
transfer registers. The horizontal transfer registers transfer the
signal charges input via the vertical transfer registers toward
an output amplifier. The output amplifier converts the signal charges
(Q) to voltages (V). The image sensor 101c executes exposure based
on actual incident light, transfer of the signal charges, resetting
of the photosensitive cells and so forth in accordance with the
drive signals output from the driver 10B. The image pickup 10d feeds
the resulting image signal 101d to the preprocessor 10e.
The preprocessor 10e includes a CDS (Correlated Double Sampling)
circuit, an amplifier, a clamper, a preliminary white balance control
circuit, a color separating circuit and an ADC (Analog-to-Digital
Converter) although not shown specifically. The preprocessor 10e
is controlled by the system controller 10j although not shown specifically,
and operates in accordance with various timing signals output from
the TG 10c. The CDS circuit removes low-frequency noise components
from an input signal. The amplifier executes AGC (Automatic Gain
Control) with the noise-free signal to thereby shape the waveform
of the signal. The damper fixes the wave-shaped signal at a preselected
reference level. The preliminary white balance control circuit executes
preliminary white balance control with the clamped signal in accordance
with, e.g., the output of a white balance sensor for optical control.
This white balance control should preferably be executed by taking
account of the primary colors or the complementary colors. The color
separating circuit separates R, G and B contained in the signal
subjected to white balance adjustment. The ADC converts the color-by-color
analog signals to digital signals 101e and feeds the digital signals
101e to the signal processor 10f.
The signal processor 10f is implemented as an RISC (Reduced Instruction
Set Computer) chip including a preprocessing buffer, an image processing
circuit, a DAC (Digital-to-Analog Converter), a PLL (Phase Locked
Loop) circuit and a compander although not shown specifically. The
signal processor 10f receives a control signal 101j from the system
controller 10j.
The preprocessing buffer includes, e.g., a lookup table for gamma
correction. The preprocessing buffer receives and temporarily stores
the digital image data 101e and executes gamma correction with the
stored image data by using the lookup table. Assume that the image
sensor 101c of the image pickup 10d has a honeycomb configuration.
Then, the image processing circuit generates, based on the image
data subjected to gamma correction, R, G and B pixel data by interpolation
at positions where pixels actually exist (real pixels) and positions
where they are absent (virtual pixels). The image processing circuit
generates high luminance data YH, which contain high-frequency components,
in addition to the R, G and B pixel data and then executes matrix
processing with the resulting image data to thereby output image
data, i.e., a luminance signal Y and color signals C.sub.r and C.sub.b.
In the preparatory mode or a movie mode, the image processing circuit
reduces, or thins, the image data subjected to gamma correction
to thereby output the image data Y, C.sub.r and C.sub.b. In the
camera mode or a still picture mode, the image processing circuit
increases the number of pixels by interpolation to thereby output
the image data Y, C.sub.r and C.sub.b. The image processing circuit
adjusts the above image data by taking account of the mode, the
number of pixels available with the monitor and so forth. The image
processing circuit delivers the reduced image data to the image
control processing section 10h while delivering the processed image
data to the DAC. The DAC converts the image data to analog signals
and feeds the analog signals to the monitor.
The PLL circuit receives a clock, not shown, from the signal generating
circuit, multiplies the clock while controlling its phase, and thereby
generates a desired frequency to be used in the signal processor
10f. The PLL circuit feeds a signal whose frequency matches a required
operation speed to each section of the signal processor 10f. The
compander is made up of an encoding circuit and a decoding circuit.
The encoding circuit compresses the image data in accordance with,
e.g., JPEG (Joint Photographic Experts Group) standards using orthogonal
transform. The decoding circuit expands the compressed image data
to thereby restore the original image data. In a record mode, the
compander feeds the compressed data, labeled 101f, to the storage
10g through a bus 32 and a signal line 101g under the control of
the system controller 10j. In a play mode, the compander reads the
compressed data out of the storage 10g through the signal line 101g
and bus 32 and expands them. At the time of compression or expansion,
the preliminary buffer may temporarily store the image data, if
desired. The expanded image data appear on the monitor through the
image control processing section 10h and DAC.
As stated above, the signal processor 10f generates image data
by image processing and delivers not only compressed data but also
data based on the previously stated function to the various sections
over the bus 32.
The storage 10g basically has a function of recording image data
in a recording medium and a function of reading them out of the
recording medium. For the storage 10g, use is made of an interface
based on ATA (AT Attachment) standards, which belong to a family
of hard disk interfaces. The storage 10g is loaded with a Smart
Media (trade name) or similar semiconductor memory, a magnetic disk,
an optical disk or similar recording medium. When use is made of
a magnetic disk or an optical disk, the storage 10g includes a circuit
for modulating image data and a head for writing the image data.
As shown in FIGS. 1A and 1B, the image control processing section
10h includes a timing adjusting section 12, a video memory 14, a
memory controller 16, a bus arbitrator 18, a display sequencer 20,
a CPU 22, a DMA (Direct Memory Access) controller 24, a signal input
26, an encoder 28, a data corrector 30, and an outside interface
(I/F) 31. The image control processing section 10h adequately reads
image data out of the video memory 14 in accordance with, e.g.,
broadcast standards while transferring them to a display unit. Generally,
the image control processing section 10h should preferably be installed
not only in the digital camera 10 but also in an image processing
unit, image display unit, printer or similar imaging apparatus.
It is preferable to implement the image control processor 10f as
a chip like the signal processor 10f.
The constituents mentioned above are controlled by the system controller
10j, which will be described later. The control function of the
system controller 10j may be assigned to the CPU 22, if desired.
In the illustrative embodiment, the CPU 22 outputs instruction
data 32a representative of the kind of processing to be applied
to the image data, as will be described specifically later. The
memory controller 16 controls the timing adjusting section 12, video
memory 14, bus arbitrator 18, and display sequencer 20. In addition,
the memory controller 16 responds to commands that may be output
from the bus arbitrator 18 and display sequencer 20 as well as from
an outside control device. In the illustrative embodiment, the outside
control device includes the DMA controller 24, signal input 26,
and outside I/F 31.
In the image control processing section 10h, the memory controller
16, bus arbitrator 18, display sequencer 20, CPU 22, DMA controller
24, signal input 26 and outside I/F 31 are connected to the bus
32. In the illustrative embodiment, the width of the bus 32 is extended
and/or an independent, exclusive line is added. This allows, e.g.,
the instruction data 32a contained in information particular to
the CPU 22 to be delivered in addition to the image data while implementing
the control, as will be described in detail later. In FIG. 1B, a
signal line 32a branching off the bus 32 is representative of the
exclusive line. FIG. 4 shows the extension of the bus width.
More specifically, the timing adjusting section 12 includes a timing
signal generator 12a and a buffer memory 12b. The timing signal
generator 12a includes two oscillators, not shown, for generating
a first and a second clock 10a and 10b, respectively. In the illustrative
embodiment, the first and second clocks 10a and 10b are respectively
implemented by a clock 4f.sub.sc often applied to broadcast standards
and a clock higher in frequency than 4f.sub.sc. The clock 4f.sub.sc
has a frequency that is, e.g., four times as high as a subcarrier
frequency f.sub.sc of 3.579545 MHZ used in the NTSC (National Television
System Committee) system, i.e., 14.31818 MHZ.
The first clock 10a is fed to the buffer memory 12b as well as
to the encoder 28, which encodes the image data output from the
buffer memory 12b. The second clock 10b may have any desired high
frequency higher than the frequency of the first clock 10a. In the
illustrative embodiment, the second clock 10b has a frequency close
to 50 MHZ. The second clock 10b is fed to the buffer memory 12b,
video memory 14, and display sequencer 20 as well as to the other
constituents through the bus 32 although not shown specifically.
When use is made of a frequency that is a multiple of the subcarrier
frequency, the timing adjusting section 12 may use a clock produced
by dividing the second clock in order to reduce the number of oscillators.
It is not necessary that the first and second clocks 10a and 10b
be synchronous to each other.
The buffer memory 12b includes a plurality of FIFO (First-In First-Out)
memories not shown. While one of the FIFO memories is outputting
data, one horizontal line of data of the video memory 14 are written
to the other FIFO memory or memories. That is, at least two FIFO
memories capable of storing two lines are used although not limitative.
The buffer memory 12b will be described more specifically later.
The video memory 14 is implemented by an SDRAM (Synchronous Dynamic
Random Access Memory) or a DRAM (Dynamic RAM). To deal with massive
image data, the video memory 14 is constituted by a plurality of
banks. When the video memory 14 is implemented by an SDRAM, the
memory 14 can be controlled bank by bank because of an access system
using commands, e.g., request signals. Further, the SDRAM implements
a bank-by-bank interleaving function in addition to the function
of an ordinary DRAM. The second clock 10b is input to the video
memory 14, as stated earlier.
The memory controller 16 controls the input and output of image
data from the video memory 14 and outputs a refresh request (REF_REQP=(logical)
ONE) meant for the video memory 14. The memory controller 16 includes
a refresh timer for a refreshing purpose. As shown in FIG. 2, the
memory controller 16 includes, e.g., an initializing function 16a,
a display control function, a bus control function 16c and a refreshing
function 16d, so that it can initialize itself and control the other
sections connected thereto.
The memory controller 16 is connected to the bus 32 by a signal
line 16e. The memory controller 16 inputs and outputs image data
from the video memory 14 via a signal line 16f while controlling
the data input and output. Further, the memory controller 16 is
connected to the buffer memory 12b by a signal line 16g. The signal
line 16g includes image data and control data fed via the signal
line 16e and various control signals for controlling the buffer
memory 12b. The functions 16a through 16d shown in FIG. 2 include
a procedure representative of hardware and software processing based
on preselected conditions.
The initializing function 16a initializes its various sections
to preselected conditions, or parameters, when the image control
processing section 10h is switched on for the first time or at the
time of buildup after resetting.
The display control function 16b causes, in response to a command,
image data to be read out by taking account of a reading order.
In the illustrative embodiment, the bus control function 16c allows
the various functions other than the bus control function 16c, i.e.,
the initializing function 16a, display control function 16b and
refreshing function 16d as well as the writing and reading functions
of an outside CPU, not shown, and the DMA function of the DMA controller
24 to selectively occupy the bus 32 in accordance with a preselected
priority order. The bus control function 16c outputs information
for enabling one of the above functions. The refreshing function
16d refreshes the video memory 14 in response to information output
from the refresh timer.
Referring again to FIGS. 1A and 1B, the bus arbitrator 18 outputs,
based on the priority order, information indicative of whether or
not the function enabled by the bus control function 16c is allowable.
The bus arbitrator 18 is connected to the display sequencer 20,
CPU 22, DMA controller 24, signal input 26 and outside I/F by input/output
lines. More specifically, the bus arbitrator 18 examines information
representative of a bus occupation request in accordance with the
priority order and then feeds information representative of allowance
to the function, which has output the request. The image control
processing section 10h gives highest priority to the refreshing
function 16d of the memory controller 16. The priority order will
be described in detail later.
As shown in FIG. 3 specifically, the display sequencer 20 includes
a data separator 20a, a color signal selector 20b, a pair generator
20c, and a packet size controller 20d. The display sequencer 20
starts operating in response to a request signal (DISP_REQ) input
thereto. The data separator 20a includes three data latches 200a,
202a and 204a each for latching eight of sixteen bits of image data
34 fed from the video memory 14.
More specifically, data latch 200a latches eight bits of the above
data at the positive-going edge of a clock CLK during the enable
period of a luminance enable signal YEN, while outputting latched
data at the above edge of the clock CLK. These eight bits of data
are luminance data Y (36). The other eight bits of data are input
to each of the other data latches 202a and 204a. The data latch
202a latches the data at the positive-going edge of the clock CLK
during the enable period of a color R enable signal CREN, while
outputting latched data at the above edge of the clock CLK. The
data latch 204b operates in the same manner as the data latch 202a
except that is receives a color B enable signal CBEN. The data latch
200a delivers the luminance data 36 separated and temporarily latched
during the consecutive enable periods to the pair generator 20c.
The data latches 202a and 204a respectively deliver color data C.sub.R
and C.sub.B separated and latched in the same manner to the color
signal selector 20b.
In response to an enlarged/reduced display request or a .times.1
or equi-scale request, the color signal selector 20b selects either
one of the color data C.sub.R and C.sub.B capable of being paired
with the luminance data Y and delivers the color data selected to
the pair generator 20c. A color select signal RLB is input to the
color signal selector 20b for color selection. The operation of
the color signal selector 20b, including a color selection timing,
will be described in detail later.
The pair generator 20c, which is also implemented as a data latch,
receives the eight-bit luminance data Y (36) and either one of the
eight-bit color data C.sub.R and C.sub.B (42), i.e., sixteen-bit
image data 44. The pair generator 20c latches the sixteen-bit image
data 44 at the positive-going edge of the clock CLK during the enable
period of a data enable signal DEN. At the same time, the pair generator
20c outputs image data 46 latched at the positive-going edge of
the clock CLK to the packet size controller 20d.
The packet size controller 20d includes a header information analyzer
206a, an S-size packer 208a, an L-size packer 210a, and an optimal
size packer 212a. The header information analyzer 206a analyzes
the size of the entire picture, date and other information attached
to, e.g., the head of the image data 46. If the analyzed size is
not a usual size, then the analyzer 206a outputs a code 48 that
enables one of the S-size packer 208a, L-size packer 210a and optimal
size packer 212a. The image data 46 are input to the S-size packer
208a, L-size packer 210a and optimal size packer 212a as well. If
the picture has the usual size, then the analyzer 206a directly
outputs the input image data 46 without varying the division of
the image data 46.
If desired, the packet size controller 20d may additionally include
a circuit for dealing with the usual size or M size so as to classify
image sizes to S size, M size and L size, as will be described specifically
later.
Assume that the header information analyzer 206a determines that
a single pattern should be repeatedly displayed. Then, the S-size
packer 208a sets the S size smaller than the usual size and then
packs the image data 46, i.e., varies the division of the image
data 46. In addition, the S-size packer 208a sets the address of
the memory that is the destination of the image data 46. While the
S-size packer 208a may repeatedly output a picture packed in the
S size, it may alternatively feed the S-size image first and then
feed only the number of times of copying of the same image.
When the header information analyzer 206a determines that the picture
should be displayed in the form of a thumbnail, the L-size packer
210a sets the L size larger than the usual size, packs the image
data, and sets the address of the destination. More specifically,
because a thumbnail picture is small size, the L-size packer 210a
sets the L size so as to effect only one time or a minimum number
of times of transfer, thereby reducing the number of times of access
during writing.
The optimal size packer 212a optimizes the packing size by taking
account of the spatial frequency of the picture. For example, a
picture of a sand dune has a low spatial frequency while a picture
of a building or similar subject needing clear details has a high
spatial frequency. The optimal size packer 212a controls the packing
size in proportion to such a difference in spatial frequency. The
optimal size packer 212a also sets the address of the destination
of the image data.
The display sequencer 20 with the above configuration allows a
pair of luminance data and color data to maintain a preselected
relation (4:2:2 in the illustrative embodiment) without regard to
a display request. Further, the display sequencer 20 packs the image
data 46 by taking account of the analyzed header information of
each image data. This successfully reduces the period of time over
which the display sequencer 20 occupies the bus 32 or the number
of times of access to the bus 32.
In the illustrative embodiment, the display sequencer 20 produces,
on a single line, eighty image packets each containing eight image
data under the control of the memory controller 16. Further, the
display sequencer 20 packets control data relating to the outside
DMA reading/writing, control data relating to the reading/writing
of the CPU 22, and image data to be interchanged with the outside
I/F 31. Such packets are written to the video memory 14 either directly
or indirectly via the bus 32 and memory controller 16. Thereafter,
the packets are read out of the video memory 14 and input to the
data corrector 30.
FIG. 4 shows a specific configuration of the data corrector 30.
As shown, the data corrector 30 includes a decoder 300, a flip-flop
(FF) 302, a register 304, a data selector 306, an electronic zoom
corrector 308, a calculator/filter 310, an aperture generator 312,
an adder 314, and a data storage 316. The decoder 300 receives image
data 52 via the memory controller 16 and at least one of data 54
representative of the number of valid pixels independent of the
data size or packet size and instruction data 32a, which is output
from the CPU 22. The decoder 300 feeds control signals 56 through
64 to the FF 302, data selector 306, electronic zoom corrector 308,
calculator/filter 310 and aperture generator 312, respectively.
When the control signal (enable signal) input to the FF 302 is
in an ON state, the FF 302 latches the image data or packet data
52 at the edge of the second clock 10b and then outputs the image
data to the data selector 306 at the next edge of the clock 10b.
The FF 302 may therefore hold the latched image data 52 when the
control signal 56 goes OFF and outputs it at a desired enable timing
later. In the illustrative embodiment, the FF 302 simply outputs
the image data 52 to the data selector 306 in response to every
clock pulse. It is to be noted that the feed of the second clock
10b to the FF 302 and register 304 is not indicated in FIG. 4.
The register 304 stores the instruction data 32a output from the
CPU 22. The instruction data 32a relates to, e.g., the background
of a picture. Having a capacity corresponding to a packet size,
the register 304 operates at the same timing as the FF 302.
The data selector 306 includes a one-line memory used to select
and copy data. In the illustrative embodiment, the data selector
306 selects one of the output 66 of the FF 302, the output 68 of
the register 304, and the image data 52 directly input thereto.
The data selector 306 receives an enable signal 58 from the decoder
300, a select signal for causing the selector 306 to select one
of the above three kinds of input data, and information indicative
of the address for storing the data selected.
Assume that the data selector 306 with the above function designates
a leading address position where the image data 52 is originally
expected to be stored, and stores the output 66 of the FF 302 by
designating the address of the one-line memory that is one-half
of the entire memory capacity. Then, despite that only half a line
of data is input to the data selector 306, the data selector 306
doubles the amount of data to thereby fill up one line as if the
data were copied.
On the other hand, assume that the data selector 306 selects and
stores, in response to an address indication, the data 68 output
from the register 304 in place of the peripheral data of a picture.
Then, as shown in FIG. 27 specifically, a picture appears as if
it were put in a frame. Further, when the decoder 300 analyzes a
picture corresponding to the S-size division, the decoder 300 may
feed the control signal 58 to the data selector 306 for causing
it to copy the input packet data the designated number of times.
This successfully increases the amount of data. In any case, the
data selector 306 delivers the resulting packet data 70 to the electronic
zoom corrector 308. Assume that the decoder 300 receives image data
corresponding in amount to a quotient produced by dividing a data
size by a value indicated by valid pixel number information. Then,
the control signal 58 output from the decoder 300 causes the data
selector 306 to repeatedly copy such an amount of image data a number
of times that is the reciprocal multiple of the above quotient.
The electronic zoom corrector 308 corrects the processed electronic
zooming packet by packet, as will be described in detail later.
The decoder 300 feeds a control signal to the electronic zoom corrector
308 in accordance with the result of analysis. In response, the
corrector 308 corrects the individual packet and applies, only when
it performs packet-by-packet correction, distortion correction and
special effect processing to the packets; otherwise, the corrector
308 simply passes the packet data therethrough. Packet-by-packet
correction makes it needless to correct packets not needing correction,
thereby obviating wasteful signal processing and promoting efficient
correction. The corrector 38 delivers packet data 72 corrected or
not corrected to the calculator/filter 310.
The calculator/filter 310 includes a calculating circuit and a
filtering circuit although not shown specifically. The calculating
circuit varies at least one of the lightness, contrast and noise
level of the individual packet data. The filtering circuit executes
special effect processing. When the filtering circuit is implemented
by a digital filter, the circuit may be regarded as a calculating
circuit. The calculator/filter 310, like the electronic zoom corrector
308, may handle the input data packet by packet in accordance with
a control signal 62 fed from the decoder 300.
For noise reduction in particular, the calculator/filter 310 may
execute coring or low-pass filtering for deleting the low-tonality
portions of a picture. The special effect available with the calculator/filter
310 may be tessellation by way of example. Further, to vary lightness
particular to the individual packet data, the calculator/filter
310 may render, e.g., only the upper half of a picture as reddish
as an evening glow.
The calculator/filter 310 simply passes the packet data therethrough
when the control is in an OFF state. Packet-by-packet correction
has the advantage stated earlier in relation to electronic zoom
correction. The calculator/filter 310 delivers packet data 74 corrected
or not corrected to the aperture generator 312 and one input terminal
314a of the adder 314.
The aperture generator 312 generates an aperture for the input
image data by either one of hardware or software. Specifically,
the aperture generator 312 includes a circuit or a procedure customarily
used for contour enhancement. The decoder 300 analyzes, based on
the instruction data 32a, information included in the packet-by-packet
information and indicating how the sharpness of the individual packet
should be dealt with. The decoder 300 feeds a control signal 64
representative of the result of analysis to the aperture generator
312. In response, the aperture generator 312 feeds a signal component
76 generated to the other input terminal 314b of the adder. The
aperture generator 312 executes no processing when the control is
in an OFF state.
The adder 314 adds the packet data 74 and the signal component
76 input thereto. Therefore, when an aperture is generated, the
adder 314 enhances the sharpness of the packet data 78 and then
feeds the packet data 78 to the buffer memory 12b. At this instant,
the decoder 300 handles the address (information) represented by
the instruction data 32a or the image data 54 as an independent
parameter and feeds a generated address 80 to the buffer memory
12b. Further, the decoder 300 feeds an enable signal 82 to the buffer
memory 12b. The input image data can therefore start being displayed
at any region display region.
The data corrector 30 has been shown and described as operating
in accordance with the instruction data 32a output from the CPU
22 every time data correction is executed. Alternatively, if processing
to be executed is fixed, then the instruction data 32a may be stored
in the data storage 316 beforehand. The data storage 316 is implemented
by a ROM (Read Only Memory) or a RAM (Random Access Memory). When
use is made of a ROM, a procedure for dealing with the instruction
data and address information is written in the data corrector 30.
When use is made of a RAM, the CPU 22 sets a data correction procedure
and writes the instruction data in the RAM when the digital camera
10 (or image control processing section 10h) is switched on. The
data storage 316 additionally stores, e.g., background data to be
fed to the register 304.
The data storage 316 delivers instruction data 84 to the decoder
300 in accordance with a clock and a read enable signal although
not shown specifically. In response, the decoder 300 outputs the
previously stated control signals and an address.
FIG. 5 shows a specific configuration of the buffer memory 12b.
As shown, the buffer memory 12b includes a R/W (Read/Write) timing
controller 120b, a read address counter 122b, a write address counter
124b, an input selector 126b, FIFO memories 128b and 130b, and an
output selector 132b. The buffer memory 12b additionally includes
a R/W clock generator not shown.
The R/W timing controller 120b receives an enable signal 86 and
a horizontal synchronizing (sync hereinafter) signal HD (88). The
R/W timing controller 120b generates a control signal 90 and a select
signal 92 in synchronism with the horizontal sync signal HD while
delivering them to the input selector 126b and output selector 132b,
respectively. The horizontal sync signal HD simply defines a timing
at which data is written to one of the FIFO memories 128b and 130b
while data is read out of the other of the same. More specifically,
the R/W timing controller 120b generates the control signal 90 and
select signal 92 in accordance with the actual read/write condition
of the first clock 10a, a reset signal (RSTL) and a blank signal
(FIFO_BLANK), although not shown specifically. The R/W timing controller
120b controls the input and output of data from the FIFO memories
128b and 130b in accordance with a bank selection condition. Further,
the R/W timing controller 120b generates a signal (FIFO_BLKST) relating
to the FIFO memories 128b and 130b and delivers it to the write
address counter 124b, although not shown specifically.
The read address counter 122b, which is a ten-bit counter, counts
read addresses and outputs the resulting count. The counter 122b
receives various timing signals 94 including a horizontal and a
vertical sync signal particular to a TV signal. The counter 122b
counts consecutive read addresses in synchronism with the timing
signal 94 while feeding a count 96 to the input selector 126b. The
counter 122b may additionally generate a masking signal, not shown,
on the basis of the first clock 10a, reset signal (RSTL) and blank
signal (FIFO_BLANK). The masking signal masks data, so that only
the image data are read out.
The write address counter 124b, which is also a ten-bit counter,
counts write addresses and outputs the resulting count. The counter
124b receives the address data 80 and enable signal 82 from the
decoder 300. The enable signal 82 allows the counter 124b to take
in the address data 80 when an instruction indicative of the writing
and reading of data in an address designated by the instruction
data 32a, which is output from the CPU 22.
More specifically, when the enable signal 82 enables the write
address counter 124b, the counter 124b takes in the address data
80 as the leading address of the destination and then counts up
the successive addresses. At the same time, the counter 124b feeds
the count to the input selector 126b as a write address 98 meant
for either one of the FIFO memories 128b and 130b. When the enable
signal 82 disenables the counter 124b, the counter 124b feeds the
write addresses 98 to the input selector 126b in the same manner
as the read address counter 122b counts up consecutive addresses
in synchronism with the timing signal 94.
As for masking, a masked position stores other control data in
the form of a packet and does not directly contribute to display.
Masking is therefore significant in that essential image data are
densely packed with the above control data being excluded. For more
sophisticated control, the write address counter 124b additionally
receives the reset signal (RSTL), a FIFO write enable signal (FIFO_WEL),
a clock (M2CLK) and the signal (FIFO_BLKST) at the time of counting,
although not shown specifically. The counter 124b generates various
timing signals on the basis of the combination of such signals.
The input selector 126b receives the control signal 90, read address
data 96, write address data 98 and packeted, sixteen-bit image data
100. The input selector 126b is connected to the FIFO memory 128b
by an address line 102, a data line 104 and an enable line 106 and
connected to the FIFO memory 130b by an address line 108, a data
line 110, and an enable line 112. When the input selector 126b feeds
a write enable signal to one of the FIFO memories 128b and 130b
via associated one of the enable lines 106 and 112, the selector
126b feeds a read enable signal to the other FIFO memory via the
other enable line. The write address data 98 and image data 100
fed to the input selector 126b are transferred to the FIFO memory
128b or 130b enabled to write. The read address data 96 also fed
to the input selector 126b is transferred to the FIFO memory 128b
or 130b enabled to read.
The other signals, not shown, will be briefly described hereinafter.
The write enable signal (FIFO_WEL) is fed to the input selector
126b. While the write enable signal is in an ON state, the input
selector 126b feeds a write disenable signal (F1_WEI) to the FIFO
memory 128b or feeds a write disenable signal (F2_WEI) to the FIFO
memory 130b in accordance with the control signal (bank select signal)
90, preventing the image data from being written to the FIFO memory
disenabled to write. Further, the input selector 126b outputs signals
(F1_V1 and F1_V2 not shown) for writing the image data in the FIFO
memories 128b and 130b bit by bit. In addition, the input selector
126b feeds other various disenable signals to the FIFO memories
128b and 130b.
The FIFO memories 128b and 130b constitute a line memory each.
A write clock and a read clock, not shown, are fed to the FIFO memories
128b and 130b such that when image data is read out of one memory,
image data is written to the other memory. The sixteen-bit image
data is input to both of the FIFO memories 128b and 130b. The FIFO
memory 128b or 130b received the write disenable signal operates
in a read mode. The image data is read out of the FIFO memory 128b
or 130b operating in the read mode and is fed to the output selector
132b. The outputs 114 and 116 of the FIFO memories 128b and 130b,
respectively, are connected to the output selector 132b such that
either one of the memories 128b and 130b can operate in the read
mode.
If desired, the two line memories 128b and 130b may be replaced
with, e.g., sixteen line memories. In such a case, when a picture
is to be displayed in the form of a thumbnail or similar small picture,
the buffer memory 12b may replace part of the picture and feed only
desired data to designated addresses in order to effect efficient
display.
The output selector 132b selects either one of the input image
data 114 and 116. In addition, the output selector 132b packets
control data fed thereto together with the image data 114 or 116
selected. To implement these functions, the first clock 10a, a signal
(DMASK), the control signal 90 and a reset signal are fed to the
output selector 132b in addition to the image data 114 and 116,
although not shown specifically. The output selector 132b produces
a sequence of sixteen-bit data 118 by inserting packets, which contain
data other than the image data as well, in a single line. The data
118 are output to the encoder 28, FIG. 1B.
The buffer memory 12b further includes a W/R clock generator not
shown. The W/R clock generator generates a write/read clock that
is one of clocks to be used in the buffer memory 12b. The W/R clock
generator receives clocks (M2CLK) and (M4CLK) as well as the first
clock 10a, second clock 10b and reset signal (RSTL). By using these
signals, the W/R clock generator feeds a write clock (F_WCK) and
a read clock (F_RCK) to the FIFO memories 128b and 130b although
not shown specifically.
Referring again to FIGS. 1A and 1B, the CPU 22 not only controls
the image control processing section 10h, but also plays the role
of an outside CPU. The CPU 22 has a CPU writing function and a CPU
reading function although not shown specifically. The CPU 22, which
is one of outside control units included in the illustrative embodiment,
delivers control information relating to write-in and control information
relating to read-out over the bus 32. These control information
correspond to the instruction data 32a. While the CPU 22 has been
dealt with as an outside unit in the above respect, it may be included
in the image control processing section 10h, if desired.
The DMA controller 24 hands over the control right to, e.g., the
interface of a peripheral apparatus and directly controls data interchange
between the interface and a main memory without the intermediary
of the CPU 22. Control information relating to write-in and control
information relating to read-out are input to and output from the
DMA controller 24, which is another outside unit. These control
data are transferred in accordance with the priority order relating
to the bus 32.
The signal input 26 corresponds to the interface of the peripheral
apparatus and may be implemented as a keyboard connected to the
bus 32. Even information other than the image data is fed from the
buffer memory 12b to the encoder 28 via the bus 32 under the control
of the memory controller 16, as stated previously.
The encoder 28 executes encoding matching with preselected broadcast
standards. Specifically, the encoder 28 selects only the image data
to be displayed out of the input packets and encodes the image data.
Encoded image data 120 are fed from the encoder 28 to a display
not shown.
For the outside I/F 31, use may be made any one of a PIO (Programmed
Input/Output), a UART (Universal Asynchronous Receiver-Transceiver),
a USB (Universal Serial Bus), the IEEE (the Institute of Electrical
and Electronics Engineers) 1394 standard and so forth. The PIO is
an interface that allows input and output to be varied on a program
basis. The UART is a device applicable to a serial interface and
capable of converting parallel signals to a serial signal or converting
a serial signal input from a serial device to parallel signals,
as desired. The interface based on the IEEE 1394 standard supports
the transfer of data of up to, e.g., 400 Mbps. This standard implements
isochronous transfer and asynchronous transfer on the same bus at
the same time. The outside I/F 31 operates under the control of
the bus arbitrator 18, as stated earlier.
In the construction described above, the image control processing
section 10h realizes the display of image data adaptive to high-speed
processing. Particularly, the image control processing section 10h
occupies the bus 32 over a period of time far shorter than conventional,
promoting the easy access of the other control section or the outside
apparatus to the memory. The digital camera 10 can therefore execute
rapid-response processing.
Further, the image control processing section 10h can execute various
kinds of signal processing with packeted image data. More specifically,
the processing section 10h executes signal processing only with
packets needing signal processing and thereby enhances efficiency.
In addition, the signal processing insures high-quality pictures
without increasing loads on system control. Moreover, even electronic
zooming, e.g., enlargement or reduction allows image data to be
sampled without disturbing the relation of pairs of data, obviating
false colors.
How and why the individual constituent of the image control processing
section 10h executes the respective processing will be described
hereinafter. First, processing to be executed in an electronic zoom
mode will be described. Assume that a single line is displayed by
640 pixels in the horizontal direction, and that the Y/C separated,
color component data of image data each are sampled by a 4:4:4 sampling
format shown in FIG. 6, (a). Then, one color data C.sub.R and one
color data C.sub.B are associated with one luminance data Y; that
is, four color data C.sub.R and four color data C.sub.B are associated
with four luminance data Y.
FIG. 6, (b), shows a 4:2:2 sampling format well known in the art.
In this system, two color data C.sub.R and two color data C.sub.B
are sampled for four luminance data Y. As shown in FIG. 6, (c),
when a picture is enlarged by two magnifications (.times.2) by electronic
zooming in accordance with the 4:2:2 sampling format, two identical
image data are positioned in the pixel interval for display.
As shown in FIG. 6, (d), when a picture is reduced to one-half
(.times.1/2) by electronic zooming in accordance with the 4:2:2
sampling format, only odd luminance data Y, for example, are sampled.
In this case, only the color data C.sub.R are sampled, so that the
color data C.sub.B are lost. On the other hand, when only even luminance
data are sampled, the color data C.sub.R are lost, although not
shown specifically. As a result, false colors appear in the picture
being displayed.
In light of the above, the display sequencer 20 with the configuration
of FIG. 3 samples the luminance data Y and color data C by using
three pulses of the second clock 10b as a unit in a particular manner
in each of three different cases, as will be described hereinafter.
Use will be made of luminance data Y.sub.n, Y.sub.n+1 and Y.sub.n+K
and color data CR.sub.n and CB.sub.n for the purpose of describing
general sampling; suffixes n and K are representative of a natural
number and a zoom coefficient, respectively.
First, when image data are continuously read out in the .times.1
mode (K=1), color data are selected at the timing shown in FIG.
7. As shown in FIG. 7, (a), because K is "1" eight bits
of luminance data Y.sub.n and Y.sub.n+1 are sampled. As shown in
FIG. 7, (b), in the case of the 4:2:2 color data sampling format
shown in FIG. 6, (b), color data are fed in the order of CR.sub.n
and CB.sub.n. When the luminance enable signal YEN is in a high
level, as shown in FIG. 7, (c), the luminance data Y.sub.n is taken
in at, e.g., the positive-going edge of the clock 10b. As shown
in FIG. 7, (d), the luminance data Yn is then output to the pair
generator 20c at the next positive-going edge of the next clock
10b.
When the color R enable signal CREN is in a high level, as shown
in FIG. 7, (e), the color data CR.sub.n is taken in at the positive-going
edge of the clock 10b. As shown in FIG. 7, (f) the color data CR.sub.n
is output at the next positive-going edge of the next clock 10b
and is continuously output. Likewise, when the color B enable signal
CBEN is in a high level, as shown in FIG. 7, (g), the color data
CB.sub.n is taken in at the positive-going edge of the clock 10b.
As shown in FIG. 7, (h) the color data CB.sub.n is output at the
positive-going edge of the third clock 10b and is continuously output.
Assume that the color signal selector 20b outputs the color select
signal RLB with signal levels shown in FIG. 7, (i). Then, the color
data C.sub.R or the color data C.sub.B is selected when the color
select signal RLB is in a low level or in a high level, respectively.
Therefore, the color signal selector 20b feeds the color data to
the pair generator 20c in the order shown in FIG. 7, (j).
As shown in FIG. 7, (k), when the pair generator 20c receives the
luminance data of FIG. 7, (d), and color data of FIG. 7, (j), at
the second clock, the data enable signal DEN input to the pair generator
20c goes high. Consequently, the pair generator 20c takes in sixteen
bits of luminance data Y.sub.n and color data CR.sub.n. It will
therefore be seen that two clocks suffice for completing color selection.
Subsequently, as shown in FIGS. 7, (l) and (m), the luminance data
and color data are output at the positive-going edge of the third
clock. Because the image data are continuously read out, two pixels
of data, i.e., pairs of luminance data and color data (Y.sub.n,
CR.sub.n) and (Y.sub.n+1, CB.sub.n) are continuously output over
two clocks. FIG. 7, (n) shows an enable signal FWEL relating to
the width of a range and output as an inverted latch output of the
data enable signal DEN.
How the display sequencer 20 adjusts sampling in the case of enlargement
or reduction will be described hereinafter. Let the suffix n be
representative of an even number. As shown in FIG. 8, (a), when
the leading luminance data Y is even data Y.sub.n three consecutive
luminance data are read out. The three luminance data are the even
luminance data Y.sub.n, odd luminance data Y.sub.n+1 next to the
data Y.sub.n, and luminance data Y.sub.n+K that takes account of
the enlargement or the reduction coefficient. At the same time,
as shown in FIG. 8, (b), the color data CR.sub.n and CB.sub.n corresponding
to the consecutive luminance data Y.sub.n and Y.sub.n+1, respectively,
are fed.
When the luminance enable signal YEN input to the data latch 200a
is in a high level, as shown in FIG. 8, (c) the luminance data Y
are taken in at the positive-going edge of the clock CLK. The data
latch 200a outputs the luminance data Y.sub.n and Y.sub.n+K in the
order shown in FIG. 8, (d), on the basis of the relation between
the luminance data Y and the positive-going edge of the clock 10b.
On the other hand, when the color R enable signal CREN is in a
high level, as shown in FIG. 8, (e), the color data CR.sub.n is
taken in at the positive-going edge of the clock 10b. As shown in
FIG. 8, (f), the color data CR.sub.n is output at the positive-going
edge of the second clock and is continuously output. Likewise, when
the color B enable signal CBEN is in a high level, as shown in FIG.
8, (g), the color data CB.sub.n is taken in at the positive-going
edge of the clock 10b. As shown in FIG. 8, (h), the color data CB.sub.n
is out put at the positive-going edge of the third clock and is
continuously output.
When the color select signal RLB input to the color signal selector
20b goes low, as shown in FIG. 8, (i), the color data CR and CB
are input to the pair generator 20c in the order shown in FIG. 8,
(j).
As shown in FIG. 8, (k), the pair generator 20c receives the luminance
data of FIG. 8, (d), and color data of FIG. 8, (j), at the second
clock. At this instant, when the data enable signal DEN input to
the pair generator 20c goes high at the third clock, sixteen bits
of luminance data Y.sub.n and color data CR.sub.n are taken in.
It will therefore be seen that three clocks suffice for completing
color selection.
At the positive-going edge of the fourth clock, the luminance data
Y.sub.n and color data CR.sub.n are output on the basis of a relation
shown in FIG. 8(l) and FIG. 8(m). Consequently, two pixels of data,
i.e., pairs of luminance data and color data (Y.sub.n, CR.sub.n)
and (Y.sub.n+1, CB.sub.n) are continuously output over three clocks
because of continuous reading. FIG. 8, (n) shows the previously
mentioned enable signal FWEL. In this case, the relation between
the luminance data and the color data particular to the 4:2:2 sampling
format is maintained.
Finally, when the leading luminance data Y included in the image
data is odd luminance data Y.sub.n+1, three luminance data Y are
read out. As shown in FIG. 9, (a), the three luminance data are
the odd luminance data Y.sub.n+1, luminance data Y.sub.n next to
the data Y.sub.n+1, and luminance data Y.sub.n+K that takes account
of the enlargement or reduction coefficient. More specifically,
as the relation between the luminance data and the color data particular
to the 4:2:2 sampling format indicates, it is necessary to match
the color CR to the leading luminance data. However, the color data
corresponding to the odd luminance data is the color CB, as will
be described later. Directly sampling such data would therefore
disturb the pairs of luminance data and color data and would thereby
bring about false colors or similar deterioration in the event of
electronic zooming. To solve this problem, when an odd number is
positioned at the head, the address of the second image data to
be read is put back by one to thereby read out the image data. The
sampling timing to follow also takes account of this point.
As shown in FIG. 9, (b), the color data CB.sub.n and CR.sub.n are
fed that respectively correspond to the luminance data Y.sub.n+1
and Y.sub.n continuously fed. This is the difference between this
case and the case described with reference to FIG. 8.
In this case, when the luminance enable signal YEN input to the
data latch 200a is in a high level, as shown in FIG. 9, (c), the
luminance data is taken in at the positive-going edge of the clock
CLK. The data latch 200a outputs the luminance data Y at the timing
shown in FIG. 9, (d) on the basis of the relation between the data
Y and the positive-going edge of the clock 10b.
As for the color data CR, assume that odd color data is positioned
at the head. Then, the color data CR.sub.n is taken in at the positive-going
edge of the second clock of the clock 10b when the color enable
signal CREN is in a high level, as shown in FIG. 9, (e). As shown
in FIG. 9, (f), the color data CR.sub.n is then output at the positive-going
edge of the third clock and is continuously output. As shown in
FIG. 9, (g), when the color B enable signal CBEN is in a high level,
the color data CB.sub.n is taken in at the positive-going edge of
the first clock of the clock 10b. As shown in FIG. 9, (h), the color
data CB.sub.n is then output at the positive-going edge of the second
clock and is continuously output.
As shown in FIG. 9, (i), the color select signal RLB input to the
color signal selector 20b goes low at the same time as the luminance
enable signal YEN for selecting the luminance data Y.sub.n+K to
be paired goes high. Consequently, the color signal selector 20b
selects the color data CB, CR and CB in this order, as shown in
FIG. 9, (j).
As shown in FIG. 9, (k), the pair generator 20c receives the luminance
data of FIG. 9, (d), and color data of FIG. 9, (j), at the second
clock. The data enable signal DEN input to the pair generator 20c
goes high at the third clock, so that sixteen bits of luminance
data Y.sub.n+1 and color data CR.sub.n are taken in. Because the
data enable signal DEN remains in a high level, two consecutive
pixels are selected. It will therefore be seen that three clocks
suffice for completing color selection.
At the positive-going edge of the fourth clock, pairs of luminance
data and color data (Y.sub.n+1, CR.sub.n) and (Y.sub.n+K, CB.sub.n),
i.e., two pixels of data are continuously output over two clock
pulses on the basis of a relation shown in FIG. 9(l) and FIG. 9(m).
FIG. 9, (n) shows the previously mentioned enable signal FWEL. In
this manner, the relation between the luminance data and the color
data particular to the 4:2:2 sampling format is maintained despite
electronic zooming.
Hereinafter will be briefly described how the bus arbitrator 18
feeds packets to the buffer memory 12b. In the illustrative embodiment,
a single packet is regarded as a sequence of eight eight-bit data,
as stated earlier. FIG. 10, (a), shows the horizontal sync signal
HD. As shown in FIG. 10, (b), packets are sequentially fed to the
buffer memory 12b during a valid scanning period indicated by the
horizontal sync signal HD. The packet data are written to either
one of the FIFO memories 128b and 130 of the buffer memory 12. Eighty
packets of image data are written on a single line. FIG. 10, (c),
shows packets with serial numbers 1 through 80; a label "FREE"
next to the packet #80 shows that no information exists. Also, a
label "REF" between the packets #79 and #80 is representative
of a packet indicative of refreshment.
As shown in FIGS. 10, (d) and (e), labels "CPU" and "DMA"
each intervene between particular packets of image data and store
information relating to, e. |