Digital Camera Patent AbstractA digital camera further includes a compression/multiplex section
for providing compressed motion picture data by compressing the
respective frames constituting a motion picture in a predetermined
operation mode, a communication interface for outputting the compressed
motion picture data in an appropriate format, and a picture selection
unit which permits a user to select a picture. When the user selects
a picture, the compression/multiplex section outputs the selected
picture instead of compressed motion picture data.
Digital Camera Patent ClaimsWhat is claimed is:
1. A digital camera, comprising: a motion picture recording unit
configured to obtain a motion picture by continuously recording
the motion picture, and a still picture recording/storage unit composed
of a still picture recording unit configured to record a still picture
by releasing a shutter and a picture storage unit configured to
store the still picture; a compression unit configured to compress
the respective frames constituting the motion picture and provides
compressed motion picture data in a predetermined operation mode;
an interface unit configured to output the compressed motion picture
data in an appropriate format and to output the still picture; a
multiplex unit configured to output the compressed motion picture
and the still picture by time-division multiplexing; and a picture
selection unit configured to permit a user to select a picture by
any of the recording of the still picture by releasing the shutter
and the designation of a picture stored in the picture storage unit,
wherein the compression unit comprises a selected picture output
unit configured to provide, when the user selects the picture by
the picture selection unit, the selected picture without compressing
the selected picture instead of the compressed motion picture data.
2. A digital camera according to claim 1, wherein the selected
picture output unit comprises a still picture compression unit configured
to compress the selected picture at a still picture compression
rate that is lower than the compression rate of the compression
unit to thereby provide the selected picture by compressing the
selected picture at the still picture compression rate instead of
the compressed motion picture data.
3. A digital camera according to claim 1, wherein the compression
unit configured to provide the compressed motion picture data further
comprises a picture reduction unit configured to thin out the pixels
of the respective frames by a predetermined procedure.
4. A digital camera according to claim 2, wherein the selected
picture output unit further comprises a gray scaling unit configured
to gray scale color picture data and a unit configured to allow
the user to select any of the still picture compression unit the
selected picture and the gray scaling unit.
5. A digital camera according to claim 2, wherein the selected
picture output unit further comprises: a binarizing unit configured
to binarize picture data; and a unit configured to allow the user
to select any of the still picture compression unit and the binarizing
unit in the compression of the selected picture.
6. A digital camera according to claim 1, wherein the picture selection
unit comprises the shutter, a release button of the shutter, and
a motion picture selection unit configured to use a picture recorded
in relation to the manipulation of the release button manipulated
by the user in the predetermined operation mode as the selected
picture.
7. A digital camera according to claim 1, wherein the picture selection
unit comprises a unit configured to allow the user to select the
still picture from still pictures stored in the picture storage
unit.
8. A digital camera according to claim 7, further comprising an
external storage device interface unit configured to allow data
to be transmitted between a detachable external storage device and
the picture storage unit biaxially as well as the external storage
device interface unit configured to allow the detachable external
storage device to be mounted and dismounted in a predetermined operation
mode.
9. A digital camera according to claim 1, wherein the still picture
recording unit and the motion picture recording unit comprise a
unit configured to obtain the selected picture by combining two
pictures recorded continuously in time.
10. A digital camera according to claim 1, further comprising a
selection button configured to permit the user to designate a selected
picture transmission rate of a selected picture transmission amount
of the selected picture, the selected picture being transmitted
during a still picture output period from the start of output of
the selected picture to the end of output thereof to a total transmission
amount of the selected picture and the motion picture which are
output during the selected picture output period, wherein the multiplex
unit is further configured to perform time-division multiplexing
of the selected picture and the motion picture so that a designated
selected picture transmission rate is achieved when the user selects
a picture by the picture selection unit at a time the selected picture
transmission rate is designated to other than 100%.
11. A digital camera according to claim 1, wherein the multiplex
unit is included in the compression unit, and is further configured
to output, when the user selects the picture by the picture selection
unit, the selected picture by time-division multiplexing the selected
picture and the compressed motion picture data, and the multiplex
unit comprises a unit configured to increase the transmission rate
of the compressed motion picture data when the data amount of the
selected picture is relatively small and decreases the transmission
rate of the compressed motion picture data when the data amount
of the selected picture is relatively large.
12. A digital camera according to claim 1, further comprising:
a picture display unit configured to display the picture; a picture
input unit configured to receive picture data from an external device;
a separation unit configured to separate a selected still picture
from the received picture data and stores the selected still picture
in the picture storage unit, and an expansion unit configured to
expand picture data that passed through the separation unit; and
a unit configured to cause the user to designate which of the output
from the compression unit and the received picture data is to be
displayed, wherein the user can selectively observe the picture
data being transmitted and the received picture data.
13. The digital camera according to claim 1, wherein the interface
unit is further configured to output the still picture in an uncompressed
format. Digital Camera Patent DescriptionFIELD OF THE INVENTION
The present invention relates to a digital camera that can record
a motion picture and a still picture and that is suitable for capturing
a motion picture and a still picture in respective conference halls
each employing a television conference system and for displaying
and transmitting them.
BACKGROUND OF THE INVENTION
Various television (TV) conference systems, which constructs a
network by personal computers (PC) each having a picture input unit
connected thereto, have hitherto been proposed.
For example, Japanese Patent Application Laid-Open No. 5-161136
proposes a system in which a motion picture recording camera and
a still picture recording camera are separately connected to one
set of a wireless picture transmission apparatus disposed in each
conference hall to transmit the progress in a conference.
A reason why the motion picture camera and the still picture camera
are separately used is that the amount of data of respective recording
pictures constituting a motion picture must be suppressed due to
the limit of a communication capability for transmitting data through
a communication path used generally at present. However, the still
picture requires a high resolution because it is often required
to print out the still picture, while it is sufficient to employ
a camera having a low resolution as the motion picture camera.
Accordingly, it is advantageous if a television conference system
can be constructed using one set of a camera capable of capturing
a motion picture and a still picture and transmitting them in an
appropriate amount of data (or data rates).
On the other hand, as digital still cameras and video cameras come
into widespread use, there can be available at present still cameras
capable of recording a motion picture of a relatively short time
and video cameras having a function for playing back a designated
frame of a motion picture as a still picture. However, any of the
existing cameras cannot output a motion picture and a still picture
at a data rate and in a system that are suitable for a television
conference system because they are not manufactured taking it into
consideration that they are used in the television conference system.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a digital camera
capable of recording a motion picture and a still picture, accumulating
at least still pictures, and outputting the motion picture and the
still picture in a format suitable for a television conference system.
According to one aspect of the present invention, there is provided
a digital camera suitable for a television conference system. The
digital camera 1 includes a motion picture recording unit which
obtains a motion picture by continuously recording it, and a still
picture recording/storage unit composed of a still picture recording
unit which records a still picture by releasing a shutter and a
picture storage unit which stores the still picture. The digital
camera further includes a compression unit which compresses the
respective frames constituting the motion picture and provides compressed
motion picture data in a predetermined operation mode, an interface
unit which outputs the compressed motion picture data in an appropriate
format, and a picture selection unit which permits a user to select
a picture by any of the recording of a still picture by releasing
the shutter and the designation of a picture stored in the picture
storage unit, wherein the compression unit includes a selected picture
output unit which provides, when the user selects a picture by the
picture selection unit, the selected picture as it is without compressing
it instead of the compressed motion picture data.
Further, the digital camera according to another aspect of the
present invention includes an audio input/storage unit which inputs
audio as audio data and stores it and a still picture recording/storage
unit composed of a still picture recording unit which records a
still picture by releasing a shutter and a picture storage unit
which stores the still picture and is suitable for a television
conference system. The digital camera includes an interface unit
which outputs the audio data to the outside in an appropriate format
in a predetermined operation mode, a picture selection unit which
permits a user to select a picture by any of the recording of a
still picture by releasing the shutter and the designation of a
picture stored in the picture storage unit, and a unit which outputs,
when the user selects a picture by the picture selection unit, the
selected picture to the outside in an appropriate format instead
of the audio data.
Other objects and features of this invention will become understood
from the following description with reference to the accompanying
drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic block diagram which shows a concept of a
digital camera according to an embodiment of the present invention.
DETAILED DESCRIPTIONS
An embodiment of the present invention will be described below
as well as the present invention will be described in detail with
reference to the accompanying drawing.
FIG. 1 is a schematic block diagram which shows a concept of a
digital camera according to an embodiment of the present invention.
The digital camera 1 of FIG. 1 includes a lens unit 10, a mechanical
shutter 20, a motor driver 30 for driving respective motors that
drive the lens and the shutter 20 of the lens unit 10, a charge
coupled device (CCD) 40 having a sufficient number (for example,
1280.times.960) of pixels as a still camera, a CCD drive circuit
50, a signal processing section 60 for performing the correlation
double sampling and the A/D conversion (conversion from an analog
signal to a digital signal) of CCD signals, a picture processing
section 70 for converting the A/D converted digital signals into
luminance Y and color difference U and V signals, a picture display
control section 80 for displaying a recorded motion picture and
an accumulated and selected still picture, a picture display section
85 for displaying the output from the picture display control section
80, a video output interface (IF) 90 for outputting the signals
from the picture display control section 80 to an external video
monitor, a compression/multiplex section 100 for compressing a recorded
motion picture (and also still pictures having been accumulated
and selected, respectively depending upon an embodiment) at a designated
data rate in a predetermined format and for multiplexing, when there
is a still picture to be transmitted, the compressed motion picture
and the still picture, a communication interface (IF) 110 for outputting
the picture output signals from the compression/multiplex section
100 to a personal computer (PC) or a communication controller for
controlling communication with other conference hall, a picture
memory 120 for temporarily storing a still picture, an external
memory interface (IF) 130 for connecting a detachable external memory
2 that accumulates pictures, a central control section 140 for controlling
the digital camera 1 in its entirety, and a manipulating section
150 having various switches through which an operator manipulates
the digital camera 1.
Among the above constitutional elements, the elements 10 to 90,
the picture memory 120, and the external memory interface 130 are
similar to those of an ordinary video camera or still camera, and
thus the detailed description thereof is omitted.
When it is premised that the output from the picture display control
section 80 is necessarily displayed on an external display device,
the picture display section 85 can be omitted.
Further, the video output interface 90 is not necessary when it
is taken into consideration that the digital camera 1 is used only
for a television conference because the personal computer or the
communication controller connected to the digital camera 1 has a
function for expanding and displaying the picture output from the
digital camera 1. However, it is preferable that the digital camera
1 includes the video output interface 90 in consideration that it
is also used as an ordinary still camera.
The personal computer or the communication controller (not shown)
is connected to the personal computer or the communication controller
of each conference hall other than that of FIG. 1 through a communication
unit, in addition to the digital camera 1 of FIG. 1, and controls
the display of the picture transmitted from each conference hall
according to an instruction from a user. The camera 1 may be connected
to the personal computer or the communication controller through
a cable or by air when the cable is employed, a universal serial
bus (USB), for example, can be used.
When the camera 1 is utilized in a television conference by connecting
it to the personal computer or the communication controller, first,
the user sets an operation mode to a television conference mode
by a predetermined switch (not shown) of the manipulating section
150.
An operation of the digital camera 1 in the television conference
mode will be described below.
The camera 1 ordinarily records a motion picture in the television
conference mode, compresses each recorded frame at a rate designated
by the compression/multiplex section 100, and outputs compressed
picture data through the communication interface 110.
However, the picture that is transmitted and played back has a
low resolution, and there arises an instance that the subjects in
the conference must be recorded as data having a high resolution.
In this instance, in the television conference mode according to
the present invention, even if the continuous data of a motion picture
is being transmitted, a picture at the moment the user depresses
a release button (this picture is referred to as a selected picture)
is stored in the picture memory 120 without being compressed and
at the same time is output through the communication interface 110.
Further, when the user designates anyone of the still pictures previously
recorded and stored in the picture memory 120, the designated picture
(which is also referred to as a selected picture) is also output
through the communication interface 110. It is needless to say that
a picture, which is selected from the pictures stored in the external
memory 2, can be output. Further, the selection of a picture may
be interactively carried out making use of the picture display section
85.
Note that, in an ordinary digital camera, a recording medium insertion
detecting switch is checked regularly to protect data, and when
no recording medium is inserted or it is intended to pull out a
recording medium, it is detected and the operation of the camera
is stopped. It is preferable in the present invention that the user
set the camera such that a recording medium can be replaced in the
mode in which the camera is transmitting recorded data to the outside
(television conference mode). With this configuration, it is possible
to replace the external memory 2 and to transmit a necessary still
picture even if the television conference is being carried out.
Simultaneously with the completion of transmission of the selected
picture, the compression/multiplex section 100 resumes the transmission
of the motion picture being recorded. This transmission method can
transmit a still picture promptly because it transmits one frame
of the still picture (selected picture) at a time by temporarily
interrupting the transmission of the motion picture. However, the
motion picture is discontinued on a receiver side because it is
not transmitted while the still picture is being transmitted.
To solve this point, a selection button is provided with the manipulating
section 150 to designate the rate (i.e., the selected picture transmission
rate) of the amount (i.e., the selected picture transmission amount)
of a selected picture, which is transmitted during a still picture
transmission period from the start of transmission of the selected
picture to the end of transmission thereof to the total amount (i.e.,
the total transmission amount) of the selected picture and a motion
picture which are transmitted during the above period so that the
user can select a desired selected picture transmission rate. When
this rate is 100%, it corresponds to the block transmission of the
one frame of the selected picture described above. When the selected
picture transmission rate is other than 100%, the compression/multiplex
section 100 outputs one frame of a still picture and a motion picture
by time-division multiplexing them.
Further, it is also possible for the central control section 140
to control the selected picture transmission rate instead of that
the user designates it. That is, a plurality of levels of selected
picture transmission rates are prepared, and when the data amount
of selected pictures is small, the transmission rate of a continuous
picture is increased (i.e., the level of the selected picture transmission
rate is reduced) so as to secure the smooth movement of a motion
picture. In contrast, when the data amount of the selected pictures
is large, the transmission rate of the continuous data is reduced
(i.e., the level of the selected picture transmission rate is increased)
so that the data transmission time of the selected pictures can
be set within a predetermined range, while the motion picture is
made awkward.
It is preferable that the picture processing section 70 insert
a code or data to a predetermined position of a recorded picture
to discriminate the recorded picture from a motion picture when
it is a still picture. With this configuration, a still picture
can be easily discriminated from a motion picture, and thus when
pictures including a code showing that they are still pictures are
received, it is sufficient to repeatedly display the pictures regardless
of that they are played back in the digital camera 1 or at the destination
to which they are transmitted. Further, the picture processing section
70 of the camera 1 that transmits still pictures inserts a code
or data which shows the stop of the still pictures to a predetermined
position of a motion picture at the timing at which the play back
of the still pictures is stopped. With this configuration, it is
sufficient for the camera that is playing back the still pictures
to repeat the play back of them until it receives the motion picture
having the code or the data indicating the stop of the still pictures.
When the compression/multiplex section 100 has a function for controlling
a compression rate, it may compress a continuous picture at a high
compression rate and a still picture or a selected picture at a
low compression rate. The compression/multiplex section 100 may
employ various types of compression methods as shown below, in addition
to compression methods of high efficiency, for example, a Moving
Picture Experts Group (MPEG), and the like applied to a motion picture.
(1) Method of Thinning Out the Pixels of Motion Picture
The number of pixels of a full picture as it is recorded can be
reduced to, for example, about 320.times.240 pixels by reducing
the number of lines thereof in horizontal and vertical directions.
In this case, vertical lines may be thinned out when the picture
is recorded and horizontal lines maybe thinned out by the compression/multiplex
section 100.
(2) Method of Gray Scaling or Binarizing Selected Picture
A recorded picture is processed and made to Y (luminance) and U
and V (color differences). Y is 8-bit multi-valued data having a
value of 0 to 255. The data rate of a still picture, which need
not be color, of still pictures can be reduced as compared with
the data rate thereof when it is color by outputting only the Y
data thereof. Further, the compression/multiplex section 100 may
be provided with a binarizing function. That is, each Y data is
converted into binary data of "1" and "0" using
the average luminance of an overall screen as a threshold value.
For example, when a picture may be a binary picture such as a document,
a drawing, a line drawing, and the like, the picture is transmitted
as a selected picture after it is binarized, thereby the data rate
thereof can be more reduced than gray scaling.
While the technology for reducing the data rate has been described
above, there is also an instance of a picture of high quality is
necessary. For this purpose, the digital camera 1 may be arranged
as described below. That is, a piezoelectric element (not shown)
capable of moving a recording element upward and downward is provided,
and the charge coupled device 40 is moved upward by one pixel after
a first picture is recorded and then a second picture is recorded.
Since the charge coupled device 40 has R, G and B filters disposed
thereon in a checkered pattern, information of respective colors
is not obtained over the entire pixels. The color information of
the entire pixels is ordinarily obtained by an interpolation. However,
since an interpolation formula has a low-pass filter (LPF) effect,
a picture is made unsharp thereby. To cope with this problem, when
the second picture, which is recorded by being dislocated by one
pixel, is used, a G signal that greatly contributes to a Y signal
can be obtained therefrom as to all the pixels, thereby a picture
of high resolution can be obtained without the need of using the
interpolation as to Y. When this picture data is transmitted, data
the quality of which is higher than that of the pixel size of the
charge coupled device 40 can be transmitted. Accordingly, even if
the charge coupled device has a small number of pixels and is used
for a motion picture, it can create and transmit a picture of high
resolution.
The digital camera 1 may further include a picture input interface
(not shown) for receiving picture data from an external device,
a separator (not shown) for separating a still picture (i.e., a
selected picture) from the received picture data and for storing
it in the picture memory 120, an expander (not shown) for expanding
the picture data having passed through the separator (i.e., a motion
picture), and a unit through which the user designates which of
the output from the compression/multiplex section 100 and the received
picture data is to be displayed so that a continuous picture from
the outside and a selected picture can be displayed or can be accumulated
and displayed on the picture display section 85. When the camera
1 has the structure described above and is used by one individual,
it is not necessary for an external personal computer or communication
controller itself to have a function for expanding and displaying
a picture. The user can selectively observe a continuous picture
being transmitted and a continuous picture from other person.
Further, the provision of a microphone (not shown), an analog processing
section (not shown) for restricting the band of microphone input
signals and for amplifying the signals, and further an encoder for
encoding the output from the analog processing section, instead
of or in addition to the motion picture recording function permits
the voice of the user to be stored in the external memory 2 and
to be output through the communication interface. In this configuration,
the audio data input from the microphone may be ordinarily output
through an audio interface, and when the user selects a picture,
the selected picture may be output to the outside through the communication
interface 110 instead of the audio data, in the television conference
mode. Alternately, when the user selects the picture, the audio
data and the selected picture may be output using time division.
As a method of selecting a picture, there is contemplated a method
of recording a still picture by releasing the shutter and a method
of selecting a picture from the pictures stored in the picture memory
120 or in the external memory 2. Ordinarily, when a still picture,
which is selected while a motion picture is being continuously transmitted,
has a large amount of data, it is also possible to complete the
transmission of the still picture data at an early time by changing
the transmission of the motion picture to the transmission of only
audio instead of transmitting the motion picture. While a motion
picture and a still picture are transmitted through the same communication
path using time division in the aforementioned embodiment, an interface
and a communication path may be provided with each of the motion
picture and the still picture.
Some kind or another memory card is used as the external memory
2 at present. However, when a small optical disc having a fast access
speed and a large capacity can be utilized in the future, it is
possible to record not only still pictures but also motion pictures
having a certain degree of length in a compressed format (at this
time, the distinction between a video camera and a digital still
camera disappears in a general user market). In this case, it is
also possible to select and transmit a motion picture recorded in
the external memory 2 instead of a motion picture being recorded
at a time necessary in a conference.
The above description only refers to an example of the embodiment
to explain the present invention. Therefore, it is easy for persons
skilled in the art to make various modifications, corrections, and
additions to the aforementioned embodiment according to the spirit
or the principle of the present invention. Thus, the present invention
should be interpreted according to only the claims without being
prepossessed by the embodiment described above.
According to the present invention, it is possible for only one
set of a camera to easily transmit not only real-time continuous
data, while its resolution is low, but also data of high resolution
including detailed information, when necessary, to an external device
without discontinuing motion picture data. Therefore, the present
invention is useful in a television conference system, and the like.
Further, the provision of the data compression rate control function
with the apparatus permits highly compressed data to be used in
the low resolution data according to claim 1 and data having a high
compression rate to be used in the high resolution data according
to claim 1. Further, the provision of the picture size change function
with the apparatus permits picture size reduced data to be used
in the low resolution data according to claim 1 and data without
the reduction of picture size to be used in the high resolution
data according to claim 1. The amount of data can be reduced by
gray scaling a selected picture. The amount of data can be more
reduced by binarizing a selected picture. A selected picture can
be selected from a motion picture that is being recorded. A selected
picture can be selected from the still pictures stored in the picture
storage unit. It is possible to replace a detachable external memory
with another external memory during a television conference and
to select a picture from the still pictures stored therein and to
transmit the selected picture. Even if the charge coupled device
has the small number of pixels and is used for a motion picture,
the device can create and transmit a picture of high resolution.
Since the rate of a selected picture to motion picture data can
be changed, the camera can slowly transmit a selected picture on
a background while giving weight to a real-time picture or can transmit
a selected picture at high velocity by reducing the data rate of
a motion picture. The camera can secure the quality level of real-time
motion picture data and the transmission time performance of a selected
picture by checking the data size of the selected picture and by
controlling the selected picture transmission rate. The provision
of the display unit with the camera main body permits motion picture
data, a selected picture and data received from the outside to be
selectively displayed thereon. Accordingly, the operability of the
camera main body and the information recognizing property of the
data received from the outside can be improved without depending
upon the display on an external device. Further, it is also possible
to transmit picture data in parallel with a conference carried out
by audio.
The present document incorporates by reference the entire contents
of Japanese priority document, 2001-062470 filed in Japan on Mar.
6, 2001.
Although the invention has been described with respect to a specific
embodiment for a complete and clear disclosure, the appended claims
are not to be thus limited but are to be construed as embodying
all modifications and alternative constructions that may occur to
one skilled in the art which fairly fall within the basic teaching
herein set forth. |