Digital Camera Patent AbstractA digital camera includes an image pick-up element that can read
out pixel data in a nondestructive manner, specifying means for
specifying addresses of a plurality of pixels thinned out among
all pixels of the image pick-up element, and data read-out means
for reading out pixel data of the specified plurality of pixels
in a destructive manner before a main exposure and pixel data of
the specified plurality of pixels in a nondestructive manner during
said main exposure.
Digital Camera Patent ClaimsWhat is claimed is:
1. A digital camera, comprising: an image pick-up element which
can read out pixel data in a nondestructive manner; specifying means
for specifying addresses of a plurality of pixels thinned out among
all pixels of said image pick-up element; data read-out means for
reading out pixel data of said specified plurality of pixels in
a destructive manner before a main exposure and pixel data of said
specified plurality of pixels in a nondestructive manner during
said main exposure; and a detector which performs a blur-detection
by using said pixel data read out in said destructive manner before
said main exposure and said pixel data read out in said nondestructive
manner during said main exposure.
2. The digital camera as recited in claim 1, further comprising
a display which displays a live-view image by using said pixel data
read out in said destructive manner before said main exposure and
said pixel data read out in said nondestructive manner during said
main exposure.
3. A pixel data read-out control apparatus, the apparatus comprising:
specifying means for specifying a plurality of pixels thinned out
among all pixels of an image pick-up element which can read out
pixel data in a nondestructive manner; read-out means for reading
out pixel data of said specified pixels in a destructive manner
before a main exposure and pixel data of said specified pixels in
a nondestructive manner during said main exposure; and a detector
which performs a blur-detection by using said pixel data read out
in said destructive manner before said main exposure and said pixel
data read out in said nondestructive manner during said main exposure.
4. The pixel data read-out control apparatus as recited in claim
3, further comprising a display which displays a live-view image
by using said pixel data read out in said destructive manner before
said main exposure and said pixel data read out in said nondestructive
manner during said main exposure.
5. A pixel data read-out control method, the method comprising:
specifying a plurality of pixels thinned out among all pixels of
an image pick-up element which can read out pixel data in a nondestructive
manner; reading out pixel data of said specified pixels in a destructive
manner before a main exposure and said pixel data in a nondestructive
manner during said main exposure; and performing a blur-detection
by using said pixel data read out in said destructive manner before
said main exposure and said pixel data read out in said nondestructive
manner during said main exposure.
6. The pixel data read-out control method as recited in claim 5,
further comprising: displaying a live-view image by using said pixel
data read out in said destructive manner before said main exposure
and said pixel data read out in said nondestructive manner during
said main exposure.
7. A digital camera, comprising: an image pick-up element which
can read out pixel data in a nondestructive manner; specifying means
for specifying pixels contained in a block of small area among all
pixels of said image pick-up element; read-out means for reading
out data of pixels contained in said block of small area in said
nondestructive manner during said exposure; a memory which stores
a fixed pattern noise table concerning said pixels contained in
said block; fixed pattern noise elimination means for performing
noise cancellation processing to said pixel data of said block obtained
by reading out in said nondestructive manner with reference to said
fixed pattern noise table; an adder which adds pixel data from which
said fixed pattern noise is eliminated to said pixels contained
in said block; and a detector which detects a blur using said added
pixel data.
8. The digital camera as recited in claim 7, wherein said specifying
means specifies pixels contained in a plurality of blocks of small
area among all pixels of said image pick-up element during an exposure,
wherein said read-out means reads out data of pixels contained in
said plurality of blocks in said nondestructive manner during said
exposure, wherein said memory stores a fixed pattern noise table
concerning said pixels contained in said plurality of blocks, wherein
said fixed pattern noise elimination means performs noise cancellation
processing to said pixel data of said plurality of blocks obtained
by reading out in said nondestructive manner with reference to said
fixed pattern noise table, and wherein said adder adds pixel data
from which said fixed pattern noise is eliminated to said pixels
contained in said plurality of blocks.
9. A blur-detection apparatus, comprising: read-out means for reading
out data of pixels in a nondestructive manner during an exposure,
said pixels being contained in a block of small area among all pixels
of an image pick-up element which can read out pixel data in a nondestructive
manner; fixed pattern noise elimination means for performing noise
cancellation processing to pixel data of said block obtained by
reading out in a nondestructive manner with reference to a table
of a fixed pattern noise corresponding to pixels contained in said
block; an adder which adds pixel data from which said fixed pattern
noise is eliminated to said pixels contained in said block; and
a detector for detecting a blur by using said added pixel data.
10. The blur-detection apparatus as recited in claim 9, wherein
said read-out means reads out data of pixels in a nondestructive
manner during an exposure, said pixels being contained in a plurality
of blocks of small area among all pixels of an image pick-up element
which can read out pixel data in a nondestructive manner, wherein
said fixed pattern noise elimination means performs noise cancellation
processing to pixel data of said plurality of blocks obtained by
reading out in a nondestructive manner with reference to a table
of a fixed pattern noise corresponding to pixels contained in said
plurality of blocks, and wherein said adder adds pixel data from
which said fixed pattern noise is eliminated to said pixels contained
in said plurality of blocks.
11. A blur-detection method, comprising: a step for reading out
data of pixels in a nondestructive manner during an exposure, said
pixels being contained in a block of small area among all pixels
of an image pick-up element which can read out pixel data in a nondestructive
manner; a step for performing noise cancellation processing to pixel
data of said block obtained by reading out in a nondestructive manner
with reference to a table of a fixed pattern noise corresponding
to pixels contained in said block; a step for adding pixel data
from which said fixed pattern noise is eliminated to said pixels
contained in said block; and a step for detecting a blur by using
said added pixel data.
12. The blur-detection method as recited in claim 11, wherein processing
defined in each of said steps is subjected to pixel data contained
in a plurality of blocks. Digital Camera Patent DescriptionThis application claims priority to Japanese Patent Applications
Nos. 2000-204079 and 2000-204083 each filed on Jul. 5, 2000, the
disclosure of which is incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a digital camera, a pixel data
read-out control apparatus and method, a blur-detection apparatus
and method.
2. Description of Related Art
A digital camera that displays a live-view image on a display unit
such as an LCD monitor is known. Furthermore, a digital camera equipped
with a hand-blur (hereinafter may simply referred to as "blur")
compensation function is also known. In order to perform such a
live-view display smoothly or to perform a highly precise blur-compensation,
it is desirable to update pixel data with a period of, for example,
about 1/30 seconds.
However, with the recent increased number of pixels of an image
pick-up element, it becomes very difficult to perform the aforementioned
processing in such a short time by reading out the pixel data of
all of the pixels of the image pick-up element. To cope with the
aforementioned drawbacks, there has been proposed to display a live-view
image in a state where the number of pixels is reduced substantially
or to perform blur-detection processing by using an image pick-up
element such as a CMOS sensor that can specify any pixels and read
out the image data of the specified pixels and reading out the data
of a plurality of specified pixels which are thinned out from all
of the pixels (hereinafter, thinned-out pixels) of the image pick-up
element.
According to a conventional digital cameras using thinned-out pixel
data, as shown in FIG. 10, a live-view display and a blur-detection
are performed by reading out the thinned-out pixel data of a plurality
of pixels before the main exposure for obtaining the picked-up image.
However, a live-view display and a blur-detection will become unavailable
when a shutter button is pressed to start the main exposure, and
then the live-view and the blur-detection will be resumed to read
out the thinned-out pixel data when the main exposure is completed
after reading out the pixel data of all of the pixels. In other
words, there is such a drawback that a live-view display and/or
a blur-detection are not performed during the main exposure.
With regard to a live-view display, Japanese Patent Laid-open Publication
No. H11-205689 discloses that a periodical read-out of pixel data
is continuously performed to the image pick-up element during the
main exposure and the image data is stored in an image holding portion
so that the storage time becomes longer than the read-out period.
However, in this structure, the pixel data is not updated during
the exposure and therefore a real time live-view display is not
performed.
On the other hand, in a digital camera equipped with a blur-detection
function, it is desirable to read out each pixel data of an image
pick-up element at high speed in order to perform a proper blur-detection.
However, in cases where a CCD is used as an image pick-up element,
since it is necessary to read out the pixel signal of all of the
pixels for every line, there is a limitation in high-speed processing.
For this reason, another proposal has been made. According to the
proposal, an image pick-up element such as a CMOS sensor that can
perform a nondestructive read-out of data is used and a plurality
of small area blocks are specified among all of the pixels of the
aforementioned image pick-up element. Then, the data of the pixels
contained in the specified block is read out in a nondestructive
manner. Then, the obtained image data is utilized for a blur-detection.
For example, Japanese Patent Laid-open Publication No. H5-130489
discloses that in order to increase the speed of block matching
processing, an image pick-up element such as a CMOS sensor that
can perform a nondestructive read-out is used, the data of the pixels
contained in the specified blocks among all of the pixels of the
aforementioned image pick-up element is read out in a nondestructive
manner, and then the read-out pixel data is transmitted to a block
matching portion. By utilizing the nondestructive read-out of the
pixel data, a blur-detection can be performed by reading out the
pixel data plural times at a high-speed period during the exposure.
According to conventional digital cameras including the aforementioned
prior art, high speed processing can be attained by performing the
nondestructive read-out of the pixel data contained in the aforementioned
specified blocks of small area. However, since a fixed pattern noise
(hereinafter referred to as "FPN") cannot be eliminated
within the image pick-up element, it is difficult to perform a highly
precise blur-detection because of the noise. Furthermore, there
also is a problem that the exposure becomes insufficient due to
the read-out of the pixel data at a high-speed period during the
exposure, resulting in a decreased blur-detection level.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a digital camera
which can perform a live-view display and a blur-detection before
a main exposure and also can perform a live-view display and a blur-detection
even during the main exposure.
It is another object of the present invention to provide a pixel
data read-out control apparatus and method which can perform a live-view
display and a blur-detection before a main exposure and also can
perform a live-view display and a blur-detection even during the
main exposure.
It is still another object of the present invention to provide
a digital camera equipped with a blur-detection function that can
perform a blur-detection in high speed and can obtain a sufficient
blur-detection level.
It is still yet another object of the present invention to provide
a blur-detection apparatus and method that can perform a blur-detection
in high speed and can obtain a sufficient blur-detection level.
According to a first aspect of the present invention, a digital
camera includes an image pick-up element which can read out pixel
data in a nondestructive manner, specifying means for specifying
addresses of a plurality of pixels thinned out among all pixels
of the image pick-up element, and data read-out means for reading
out pixel data of the specified plurality of pixels in a destructive
manner before a main exposure and pixel data of the specified plurality
of pixels in a nondestructive manner during the main exposure.
In this digital camera, addresses of a plurality of pixels thinned
out among all of the pixels of the image pick-up element that can
read out image data in a nondestructive manner are specified. The
plurality of specified pixels whose addresses are read out in a
destructive manner before the main exposure and in a nondestructive
manner during the main exposure. Thus, the newest pixel data can
be used even during the main exposure. Accordingly, it becomes possible
to perform a live-view display and a blur-detection.
According to a second aspect of the present invention, a pixel
data read-out control apparatus includes specifying means for specifying
a plurality of pixels thinned out among all pixels of an image pick-up
element which can read out pixel data in a nondestructive manner,
and read-out means for reading out pixel data of the specified pixels
in a destructive manner before a main exposure and pixel data of
the specified pixels in a nondestructive manner during the main
exposure.
With this read-out control apparatus, a plurality of pixels thinned
out among all pixels of an image pick-up element which can read
out pixel data in a nondestructive manner are specified. The specified
pixel data are read out in a destructive manner before a main exposure
and in a nondestructive manner during the main exposure. Thus, the
newest pixel data can be used even during the main exposure. Accordingly,
it becomes possible to perform a live-view display and a blur-detection.
According to a third aspect of the present invention, a pixel data
read-out control method includes the steps of specifying a plurality
of pixels thinned out among all pixels of an image pick-up element
which can read out pixel data in a nondestructive manner, and reading
out pixel data of the specified pixels in a destructive manner before
a main exposure and the pixel data in a nondestructive manner during
the main exposure.
With this control method, since the pixel data of the plurality
of specified pixels are read out in a destructive manner before
the main exposure and in a nondestructive manner during the main
exposure, the newest data can be used even during the main exposure,
enabling a live-view display and a blur-detection.
According to a fourth aspect of the present invention, a digital
camera includes an image pick-up element which can read out pixel
data in a nondestructive manner, specifying means for specifying
pixels contained in a block of small area among all pixels of the
image pick-up element, read-out means for reading out data of pixels
contained in the block of small area in the nondestructive manner
during the exposure, a memory which stores a fixed pattern noise
table concerning the pixels contained in the block, fixed pattern
noise elimination means for performing noise cancellation processing
to the pixel data of the block obtained by reading out in the nondestructive
manner with reference to the fixed pattern noise table, an adder
which adds pixel data from which the fixed pattern noise is eliminated
to the pixels contained in the block; and a detector which detects
a blur using the added pixel data.
With this digital camera, pixel data contained in the block of
small area among all of the pixels of the image pickup element are
specified by the specifying means. The data of pixels contained
in the block of small area is read out in a nondestructive manner
during the exposure. Furthermore, the read-out pixel data are subjected
to the noise cancellation processing by the fixed pattern noise
elimination means. The pixel data in the block from which noise
is eliminated are added by the adder, and a blur is further detected
by the detector.
Thus, since the pixel data contained in the block of small area
among all of the pixels of the image pick-up element are read out
in a nondestructive manner during the exposure, it becomes possible
to attain a high speed blur-detection processing. Furthermore, since
noise cancellation processing is performed, it becomes possible
to attain a highly precise blur-detection. Furthermore, since a
plurality of pixel data that the noise cancellation is performed
are added in the block, data having a sufficient blur-detection
level that the underexposure or the like is corrected can be secured
as the whole block.
According to a fifth aspect of the present invention, a blur-detection
apparatus includes read-out means for reading out data of pixels
in a nondestructive manner during an exposure, the pixels being
contained in a block of small area among all pixels of an image
pick-up element which can read out pixel data in a nondestructive
manner, fixed pattern noise elimination means for performing noise
cancellation processing to pixel data of the block obtained by reading
out in a nondestructive manner with reference to a table of a fixed
pattern noise corresponding to pixels contained in the block, an
adder which adds pixel data from which the fixed pattern noise is
eliminated to the pixels contained in the block, and a detector
for detecting a blur by using the added pixel data.
With this blur-detection apparatus, since data of pixels contained
in a block of small area among all pixels of an image pick-up element
are read in a nondestructive manner during an exposure, it becomes
possible to attain a high speed blur-detection processing. Furthermore,
since the noise cancellation processing is performed, it becomes
possible to attain a highly precise blur-detection. In addition,
since a plurality of pixel data that the noise cancellation is performed
are added in the block, data having a sufficient blur-detection
level that the underexposure or the like is corrected can be secured
as the whole block.
According to a sixth aspect of the present invention, a blur-detection
method includes a step for reading out data of pixels in a nondestructive
manner during an exposure, the pixels being contained in a block
of small area among all pixels of an image pick-up element which
can read out pixel data in a nondestructive manner, a step for performing
noise cancellation processing to pixel data of the block obtained
by reading out in a nondestructive manner with reference to a table
of a fixed pattern noise corresponding to pixels contained in the
block, a step for adding pixel data from which the fixed pattern
noise is eliminated to the pixels contained in the block, and a
step for detecting a blur by using the added pixel data.
In this blur-detection method, since the pixel data contained in
the specified clock of small area among all of the pixels of the
image pick-up element are read out in a nondestructive manner during
an exposure, it becomes possible to attain high speed processing
of a blur-detection. Furthermore, since noise cancellation processing
is performed, it becomes possible to attain a highly precise blur-detection.
Furthermore, since a plurality of pixel data that the noise cancellation
is performed are added in the block, data having a sufficient blur-detection
level that the underexposure or the like is corrected can be secured
as the whole block.
Other objects and the features will be apparent from the following
detailed description of the present invention with reference to
the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be more fully described and better understood
from the following description, taken with the appended drawings,
in which:
FIG. 1 is a perspective view showing a digital camera according
to a first embodiment of the present invention;
FIG. 2 Is a rear view of the digital camera;
FIG. 3 is a block diagram showing a pixel structure of an image
pick-up element of the digital camera;
FIG. 4 is a block diagram showing an electric structure of the
digital camera;
FIG. 5 is an explanatory view showing an example of a selection
of plural specified pixels in the image pick-up element;
FIG. 6 is an explanatory drawing showing a read-out timing of a
pixel signal of the image pick-up element;
FIG. 7 is a block diagram showing an electric structure of a digital
camera according to a second embodiment of the present invention;
FIG. 8 is an explanatory drawing showing a small area specified
block of the image pick-up element;
FIG. 9 is an explanatory drawing showing a read-out timing of a
pixel signal of the image pick-up element; and
FIG. 10 is an explanatory drawing showing the relationship between
a reset of a pixel signal and an image read-out timing in a conventional
digital camera.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a perspective view showing a digital camera according
to a first embodiment of the present invention, and FIG. 2 is a
rear view of the digital camera.
As shown in FIGS. 1 and 2, on the front face of the camera main
body 5A of the digital camera 5, an image-taking lens 51 is provided.
On the front upper portion thereof, a finder window 54, a distance
measurement window 59, etc. are provided. In the camera main body
5A, an image pick-up element 403, which receives an optical image
formed by the aforementioned image-taking lens 51 and performs a
photoelectric conversion of the optical image, is disposed. In this
embodiment, this image pick-up element 403 is comprised of a CMOS
sensor that can read out pixel data in a nondestructive manner.
Furthermore, on the upper surface of the camera main body 5A, a
shutter button 53, image-taking mode keys 57, a liquid crystal panel
58, etc. are provided. At the side surface of the camera main body
5A, an insertion slit 56 into which a recording media 55 is removably
inserted is provided.
The image-taking mode keys 57 are used for setting an exposure
condition, such as an iris priority exposure and a shutter speed
priority exposure, changing macro image-taking modes or setting
a zoom condition while confirming the contents displayed on the
liquid crystal display panel 58.
Furthermore, an LCD monitor 413a for a live-view display, image-processing
mode setting keys 501, etc. are provided on the rear face of the
camera main body 5A. A blur-compensation mode can be set up by the
image-processing mode setting keys 501 while looking at the display
of the LCD monitor 413a.
This digital camera 5 can record a picked-up image obtained by
the image pick-up element 403 into the recording media 55 in the
same way as conventional digital cameras, and has a function for
performing a blur-detection during a main exposure for acquiring
the picked-up image when a blur-compensation mode is set. However,
the blur-compensation function may be set automatically without
manually manipulating the image-processing mode setting keys. Furthermore,
this digital camera 5 is designed such that a live-view display
can be displayed on the LCD monitor 413a not only before a main
exposure but also during the main exposure.
As will be explained later, the blur-detection and the live-view
display during the main exposure are performed by specifying the
addresses of plural thinned-out pixels among the pixels P (FIG.
3) of the CMOS sensor as the image pick-up element 403 and reading
out the pixel data in a nondestructive manner.
FIG. 3 shows a pixel structure of the active pixel CMOS sensor
constituting the image pick-up element 403. The image pick-up element
403 includes a number of pixels P arranged in the shape of a matrix
as well known. In FIG. 3, for the purpose of simplicity, 2.times.2
pixels are illustrated.
In FIG. 3, one pixel P includes a photodiode 105 as a light-receiving
element connected to a transistor 104 of a CMOS type constituting
a reset switch, a transistor 106 for amplifying the pixel signal
of the photodiode 105, a line-selection transistors 107 connected
to the transistor 106 in series and controlled by a vertical direction
selecting circuitry 101, etc. In FIG. 3, the reference numerals
102, 108, 109 and 110 denote a reset line, a line selecting address
line, a signal line and an output amplifier on an output line 103,
respectively. Furthermore, the reference numerals 111 and 112 denote
a noise cancellation circuit and a horizontal direction selecting
circuit for selecting a pixel row, respectively.
In this image pick-up element 403, by impressing a control signal
to the horizontal direction selecting circuit 112 and the vertical
direction selecting circuit 101 from outside, one or more pixels
P can be specified, and the pixel data of the photodiode 105 of
the specified pixel P is taken out through the output line 113 by
way of the signal line 109, and is sent out as image data through
the output amplifier 110. Thus, by specifying a desired pixel by
the horizontal direction selecting circuit 112 and the vertical
direction selecting circuit 101, it becomes possible to read out
only the required pixel data at a high-speed period.
In a usual read-out (a destructive read-out) in this kind of image
pick-up element 403, it is possible to cancel the fixed pattern
noise (FPN) due to a scattering of the threshold or the like of
the amplifying transistor 106 within the image pick-up element 403.
Concretely, the noise cancellation processing can be performed by
reading out the charges photoelectrically converted by and accumulated
in the photodiode 105 and holding the charges in the noise cancellation
circuit 111, subsequently reading out the charges again after the
reset by the reset transistor 104 and holding the charges in the
noise cancellation circuit 111, and then performing a subtraction
of these two signals.
Furthermore, in this kind of image pick-up element 403, it is possible
to perform a nondestructive read-out, i.e., to read out the accumulated
pixel data photoelectrically converted by the photodiode without
destroying the pixel data, because the read-out will be not performed
in the reset state unlike the destructive read-out. This enables
the read-out without loosing the accumulated charges in the photodiode
105 even during the exposure.
However, in the aforementioned nondestructive reading, since the
reading in the reset state is not performed, noise cancellation
processing cannot be performed within the image pick-up element
403. Therefore, in this embodiment, an implication output for one
screen is stored in the memory as an FPN table. Then, the noise
cancellation processing is performed by subtracting the corresponding
implication output from the pixel data.
FIG. 4 shows a block diagram of the electric structure of the aforementioned
digital camera 5.
This digital camera 5 is equipped with an addressing portion 402
which also serves as an image pick-up element driving portion, a
control CPU 404 which controls the whole camera, an A/D converter
405 which converts an analog image signal into a digital image signal
by the image pick-up element 403, a blur-detection portion 409 which
detects a blur, a blur-compensation portion 411, an image memory
412, a live-view display 413, a media recording portion (driver)
414 corresponding to the recording media 55, etc. Also equipped
to the digital camera 5 are an FPN removal portion 406, a thinned-out
read-out pixel FPN table storing memory 407, a switching portion
408 that switches the sending out of the digital image data and
a blur-locus storing memory-cum-thinned-out image storing memory
410.
In order to perform a live-view display, etc., which will be mentioned
later, the addressing portion 402 performs the addressing of pixel
data as shown in FIG. 5 so that each pixel data of plural thinned-out
specified pixels Ps among all of the pixels P constituting the light-receiving
side 403a of the image pick-up element 403 can be read out in a
destructive manner before the main exposure, and so that each pixel
data of the plural specified pixels Ps can be read out in a nondestructive
manner during the exposure.
The control CPU 404 controls the read-out of the pixel data of
plural specified pixels Ps of the image pick-up element 403 through
the addressing portion 402, and also controls the FPN removal portion
406, the thinned-out read-out pixel FPN table storing memory 407,
the switching portion 408 and the blur-locus storing memory-cum-thinned-out
image storing memory 410.
The FPN removal portion 406 has a function which eliminates the
FPN that cancellation processing cannot be carried out within the
image pick-up element 403 with reference to the data of the FPN
table 407 only for a plurality of the specified pixels Ps when the
pixel data is read out in a nondestructive manner from a plurality
of the specified pixels. The thinned-out read-out pixel FPN table
storing memory 407 stores the FPN data of the specified pixels in
the FPN table.
The blur-detection portion 409 stores the pixel data obtained by
reading out the plurality of specified pixels Ps in the blur-locus
storing memory-cum-thinned-out image storing memory 410. As for
the subsequent pixel data, the blur-detection portion 409 calculates
the blur-locus by comparing the subsequent image data with the previous
image data, and then stores the calculated results in the blur-locus
storing memory-cum-thinned-out image storing memory 410.
The blur-compensation portion 411 has a function which rectifies
a hand-blur by using the blur-locus stored in the blur-locus storing
memory-cum-thinned-out image storing memory 410.
The live-view display 413 displays a live-view display by processing
the pixel data obtained by the destructive readout before the main
exposure and the pixel data obtained by the nondestructive read-out
during the main exposure. The live-view display 413 has the liquid
crystal display monitor 413a.
Next, the operation of the digital camera 5 shown in FIGS. 1 to
3 will be explained with reference to FIGS. 4 to 6.
A photographic object image is received by the image pick-up element
403 through the optical system 401 including the image-taking lens
51, and then photoelectrically converted every each pixel P depending
on a light-receiving amount.
(1) Before the Main Exposure
As shown in FIG. 6, the control CPU 404 controls the addressing
portion 402 such that the read-out of the pixel data of the plurality
of specified pixels Ps of the image pick-up element 403 and the
reset thereof, i.e., the destructive read-out, are performed at
a predetermined period (for example, 1/30 seconds), and also controls
the switching section 408 such that the pixel data read out in a
destructive manner is sent to the FPN removal section 406.
The pixel data read out in a destructive manner is converted into
digital pixel data by the A/D-conversion circuit 405, and the digital
pixel data is sent to the FPN removal portion 406 through the switching
portion 408.
As mentioned above, the pixel data read out in a destructive manner
has been subjected to the cancellation processing of the FPN within
the image pick-up element 403. Therefore, the pixel data sent to
this FPN removal portion 406 is sent out to the live-view display
413 and the blur-detection portion 409 as it is without being processed
in the FPN removal portion 406.
The live-view display 413 processes the sent pixel data as required
for the live-view display, and performs the live-view display on
the LCD monitor 413a. Since the pixel data is read from the plurality
of specified pixels Ps at this time, even if the total number of
the pixels P of the image pick-up element 403 is large, it is possible
to read out the pixel data at a high-speed period, enabling a smooth
image change display, for example, in every 30 seconds.
The pixel data of the first sheet obtained by the destructive read-out
of the plurality of specified pixels Ps in the blur-detection portion
409 is stored/saved as it is in the blur-locus storing memory-cum-thinned-out
image storing memory 410. As for the subsequent pixel data obtained
by the destructive read-out, the blur-locus is calculated by using
the pixel data obtained by the previous destructive read-out. Both
the pixel data obtained by the destructive read-out and the calculated
blur-locus is stored/saved in the blur-locus storing memory-cum-thinned-out
image storing memory 410.
Thus, the pixel data obtained by the destructive read-out for a
plurality of sheets and the blur-locus data will be saved in the
blur-locus storing memory-cum-thinned-out image storing memory 410.
The aforementioned plurality sheets mean the specified number of
sheets required for the blur-locus operation. If the number exceeds
the specified number, the pixel data obtained by the oldest destructive
read-out will be destroyed, and only the newest pixel data will
be saved.
(2) During the main exposure period
When the release button 53 is pressed, as shown in FIG. 6, all
of the pixels P will be reset one by one, and the main exposure
will start. The main exposure period is set longer than the changing
period ( 1/30 seconds) of the live-view. Since a blur hardly occurs
when the main exposure period is 1/30 seconds or less, it is not
necessary to perform a nondestructive read-out during the main exposure.
It is apparent that a nondestructive read-out for the live-view
every 1/30 seconds is not required.
The control CPU 404 controls the addressing portion 402 so that
the pixel data of the plurality of specified pixels can be read
out in a nondestructive manner in order to perform a live-view display
at the aforementioned period even in the main exposure period, and
further controls the switching portion 408 so that the pixel data
read out in a nondestructive manner can be sent to the FPN removal
portion 406.
The pixel data read out in a nondestructive manner will be converted
into digital pixel data by the A/D conversion circuit 405, and the
digitalized pixel data is sent to the FPN removal portion 406 through
the switching portion 408.
As mentioned above, in cases where the nondestructive read-out
is performed, the cancellation processing of the FPN cannot be performed
within the image pick-up element 403. Therefore, in the FPN removal
portion 406, the corresponding noise data of the pixels in the thinned-out
read-out image FPN table is subtracted from the obtained pixel data
to perform the cancellation processing of the FPN.
The pixel data from which the FPN is eliminated is sent to the
live-view display 413 and the blur-detection portion 409. The live-view
display 413 processes the sent pixel data as required for a live-view
display and displays the live-view.
As mentioned above, since a plurality of pixels Ps are specified
and the pixel data is read out in a nondestructive manner even during
the main exposure, it is possible to process the pixel data at a
high-speed period. Further, since the pixel data will be updated
whenever the pixel data is read out, a live-view at a real time
can be obtained.
In the blur-detection portion 409, the pixel data of the first
sheet obtained by the nondestructive read-out of the plurality of
specified pixels Ps will be stored/saved as it is in the blur-locus
storing memory-cum-thinned-out image storing memory 410. As for
the subsequent pixel data obtained by the nondestructive read-out,
the blur-locus is calculated by using the pixel data obtained by
the previous nondestructive read-out. Both the pixel data obtained
by the nondestructive read-out and the calculated blur-locus are
stored/saved in the blur-locus storing memory-cum-thinned-out image
storing memory 410.
Thus, the pixel data obtained by the nondestructive read-out for
a plurality of sheets and the blur-locus data are saved in the blur-locus
storing memory-cum-thinned-out image storing memory 410.
The aforementioned plurality of sheets mean the specified number
of sheets required for the blur-locus operation. If the number exceeds
the specified number, the oldest pixel data obtained by the nondestructive
read-out is destroyed, and only the newest pixel data is saved.
As mentioned above, since a continuous blur-detection that lasts
from before the exposure till during the exposure is performed,
the prediction error of blur becomes small. In other words, the
blur-detection precision will be high and the blur-compensation
can be performed exactly.
(3) Main Exposure Period End
After the main exposure period terminates, in order to perform
the destructive read-out of the pixel data of all of the pixels,
the control CPU 404 controls the addressing portion 402 so that
the pixel data in the plurality of specified pixels Ps is read out
in a destructive manner and thereafter the pixel data of the remaining
pixels P is read out in a destructive manner. Furthermore, the control
CPU 404 controls the switching portion 408 such that only the pixel
data of the plurality of specified pixel data is processed by the
blur-detection portion 409 and that the pixel data of all of the
pixels P is processed by the blur-compensation portion 411.
Since the pixel data of the plurality of specified pixels Ps is
first read when a destructive read-out of the pixel data of all
of the pixels P is performed, it is easily realizable to selectively
send out the pixel data of a plurality of specified pixels Ps from
the pixel data of all of the pixels P obtained by the destructive
read-out.
The pixel data of all of the pixels P obtained by the destructive
read-out is converted into digital pixel data by the A/D conversion
circuit 405, and the digitalized pixel data is sent to the FPN removal
portion 406 through the switching portion 408.
Since the pixel data sent to the FPN removal portion 406 is obtained
by the destructive read-out, it is not required to perform the FPN
removal processing and can be sent out to the live-view display
413 and the blur-detection portion 409 as it is.
In the blur-detection portion 409, a blur-locus is calculated by
using the pixel data obtained by the last nondestructive read-out.
Both the pixel data obtained by the destructive read-out and the
calculated blur-locus data are stored/saved in the blur-locus storing
memory-cum-thinned-out image storing memory 410.
In the blur-compensation portion 411, the data of all of the pixels
obtained by the destructive read-out is subjected to a blur-restoration
processing by using the blur-locus data stored in the blur-locus
storing memory-cum-thinned-out image storing memory 410 from before
the main exposure till the termination of the main exposure period.
Then, the restored pixel data is sent to the image memory 412 to
be saved as a picked-up image.
The image saved in this image memory 412 can be displayed on the
LCD monitor 413a of the live-view display 413, or can be recorded
in the recording media 55 provided in the media recording portion
414 in accordance with the operation by a user.
Next, the second embodiment according to the present invention
will be explained.
The digital camera according to the second embodiment of the present
invention has the same appearance as the digital camera according
to the first embodiment shown in FIGS. 1 and 2. In other words,
the digital camera 5 is equipped with an image-taking lens 51, a
finder window 54, a distance measurement window 59, a shutter button
53, image-taking mode keys 57, a liquid crystal panel 58, an insertion
slit 56 into which a recording media 55 can be removably inserted,
an LCD monitor 413a, image-processing mode setting keys 501, etc.
Since the function of each of these portions is the same as that
of the digital camera according to the first embodiment, the explanation
will be omitted.
Furthermore, in the camera main body 5A, an image pick-up element
203 which receives an optical image formed by the image pick-up
lens 51 and photoelectrically converts the optical image is provided.
In this embodiment, the image pick-up element 203 consists of a
CMOS sensor which can perform a nondestructive read-out of pixel
data in the same manner as in the image pick-up element of the digital
camera according to the first embodiment.
This digital camera 1 can record the picked-up image obtained by
the image pick-up element 203 in the recording media 213 in the
same manner as in a conventional digital camera, and has a blur-compensation
function which will be executed when the blur-compensation mode
is setup. Of course, the digital camera may be constituted such
that the blur-compensation function will be automatically performed
without setting the blur-compensation mode.
The aforementioned blur-compensation function performs the blur-compensation
by performing the blur-detection utilizing the nondestructive read-out
of the pixel data of the pixels P of the CMOS sensor and the address
read-out to the Pixels P with a CMOS sensor as the image pick-up
element 203.
The structure of the image pick-up element 203 is the same as that
shown in FIG. 3.
FIG. 7 is a block diagram showing the electric structure of the
digital camera 1 according to the second embodiment.
This digital camera 1 is provided with an image pick-up element
driving portion 202, a control CPU 204 which controls the whole
camera, an A/D converter 205 which converts an analog image signal
into a digital image signal by the image pick-up element 203, a
blur-detection portion 209 which detects a blur and a blur-compensation
portion 211, an image memory 212, a recording media 213, etc. Furthermore,
this digital camera 1 is equipped with an FPN removal portion 206,
an FPN table 207 corresponding to a specified block Q, a switching
portion 208 that switches the sending destination of the digital
image data, a blur-locus storing memory-cum-plural block image storing
memory 210, a pixel adding portion 214 and a frame subtraction portion
215.
For a blur-detection which will be mentioned later, the image pick-up
element driving portion 202 specifies the addresses of the pixels
contained in the plurality of specified small area blocks Q (FIG.
8) among all of the pixels constituting the light-receiving side
203a of the image pick-up element 203 during an exposure so that
these data can be read out in a nondestructive manner, and also
specifies the addresses of all of the pixels P of the image pick-up
element 203 so that these data can be read out in a destructive
manner when the exposure is terminated.
The control CPU 204 controls the read-out of the pixel data of
the image pick-up element 203 through the image pick-up element
driving portion 202, and also controls the FPN removal portion 206,
the FPN table 207 and also a blur-locus storing memory-cum-plural
block image storing memory 210.
For the blur-detection, the aforementioned each specified block
Q comprises any areas selected from all of the pixels P of the image
pick-up element 203, as shown in FIG. 8.
The time for reading out only the illustrated specified blocks
Q becomes much shorter than that for reading out all of the pixels.
For example, assuming that all of the 1,200,000 pixels are read
out in 100 ms and each block Q includes 200.times.250=50,000 pixels,
the time required for reading out all of the pixel signals of the
six specified blocks Q (a total of 300,000 pixels) Q will be 1/4
of the time required for reading out all of the pixels, i.e., 25
ms. This shows that the blur-detection can be performed in the period
of 25 ms.
If it is required to perform the blur-detection in a quicker period,
what is necessary is to make the size of the specified block Q smaller,
or to decrease the number of the specified block Q. On the contrary,
if it is allowed to perform the blur-detection in a slower period,
what is necessary is to enlarge the size of specified block Q, or
to increase the number of specified blocks Q.
The FPN removal portion 206 has a function that eliminates the
FPN which cannot be processed within the image pick-up element 203
with reference to the data of the FPN table 207 corresponding to
each specified block Q, in cases where it is switched by the switching
portion 208 and pixel data is read out from the specified block
Q in a nondestructive manner during an exposure.
The pixel adding portion 214 adds the pixel data of a plurality
of pixels P contained in each specified block Q so that the added
data become a signal level required for the blur-detection. Furthermore,
the frame subtraction portion 215 subtracts the previously added
pixel data from the present added pixel data to obtain the data
of this time.
The blur-locus storing memory-cum-plural image storing memory 210
stores the previously added pixel data and the frame data of this
time subtracted by the frame subtraction portion 215.
In the blur-detection portion 209, the blur-locus is calculated
using the sent frame data of this time and the previous frame data
stored in the blur-locus storing memory-cum-plural image storing
memory 210.
Next, the operation of the digital camera 1 having the aforementioned
structure will be explained with reference to FIGS. 7 9. In the
following explanation, the fundamental control of the camera, such
as a lens driving, an iris-diaphragm driving, an LCD driving and
a flash driving, will be omitted since these are well known.
First, a photographic object image is received by the image pick-up
element 203 through the optical system 201 including the image-taking
lens 51, and photoelectrically converted by the image pick-up element
203 depending on the light-receiving amount of each pixel P.
When the shutter button 53 is pressed, all of the pixels P are
reset and an exposure is started. During the exposure, the control
CPU 204 controls the image pick-up element driving portion 202 so
that the nondestructive read-out of the pixel data of the pixels
contained in the plurality of specified block Q among the pixels
P in the image pick-up element 203 is performed, and also controls
the switching portion 208 so that the obtained image data is sent
to the FPN removal portion 206.
The read-out timing of the pixel signal of the image pick-up element
203 is shown in FIG. 9. In FIG. 9, the vertical axis shows the line
direction of the image pick-up element 203, and the horizontal axis
shows a time.
The exposure time is from the initial reset (the start of the exposure)
to the last destructive read-out (the end of the exposure). In the
illustrated example, the nondestructive read-out is performed three
times only to the plurality of specified blocks Q during the exposure
period. In this case, in order to make the storage time of each
line of the specified block Q become equal, the reset at the time
of the exposure start is performed one by one from the line with
the specified block Q which performs the nondestructive read-out.
With this, after the termination of the exposure, the read-out order
of all of the pixels is performed in sequence from the line in which
the specified block Q exists.
Furthermore, although the nondestructive read-out of the pixel
data of each specified block Q is performed during the exposure,
what is required for a blur-detection is the pixel signal accumulated
from the read-out to the subsequent read-out. That is, as shown
in FIG. 9 showing the storage time for a blur-detection, the initial
storage time is from the reset to the first nondestructive read-out,
and the last storage time is from the last nondestructive read-out
to all pixel read-out, and the intermediate storage time is from
a nondestructive read-out from the subsequent nondestructive read-out.
This can be obtained by subtracting the previously read-out pixel
data from the currently read-out pixel data.
In the example shown in FIG. 9, although the nondestructive read-out
is performed for the specified block three times during the exposure,
the number of times for the nondestructive read-out is not limited
to this.
Returning to FIG. 7, the pixel signal obtained by the nondestructive
read-out performed by the image pick-up element 203 is converted
into digital pixel data by the A/D converter 205, and sent to the
FPN removal portion 206 through the switching portion 208.
In the FPN removal portion 206, the noise cancellation processing
is performed by subtracting the corresponding noise data stored
in the FPN table 207 from the sent pixel data. The pixel data that
the noise cancellation processing was performed is sent to the pixel
adding portion 214.
The memory space required for the table 207 of the FPN removal
can be small as compared with the case having an FPN table for all
of the pixels. For example, as mentioned above, in the case of 200.times.250=50,000
pixels, the memory space will be one fourth. Furthermore, since
the pixel data obtained by the nondestructive read-out is subjected
to the noise cancellation processing by the aforementioned FPN removal
portion 206, the blur-detection can be performed with high precision.
In the pixel adding portion 214, the pixel data corresponding to
the pixel P is added every specified block Q, and the added pixel
data will be sent to the frame subtraction portion 215 and also
to the blur-locus storing memory-cum-plural image storing memory
210 for storing the added image data.
In the aforementioned pixel adding portion 214, for example, the
block may be divided into blocks of 2.times.2=4 pixels, the pixel
data corresponding to each of these 4 pixels P may be added to obtain
the 1-pixel image data for the blur-detection. By this, an underexposure
due to a high-speed period read-out will be corrected to become
the same level as the image data level during the main exposure.
Thus, a sufficient blur-detection level can be secured. Of course,
the number of pixels to be added and the division method of the
block Q are not limited to the above, and can be arbitrarily set,
provided that a signal required for a blur-detection is obtained.
In the frame subtraction portion 215, the frame data of this time
is obtained by subtracting the previously added pixel data from
the pixel data to which addition processing was performed. The obtained
frame data of this time is sent to the blur-detection portion 209
and also to the blur-locus storing memory-cum-plural image storing
memory 210, and stored therein.
In the blur-detection portion 209, the blur-locus is calculated
from the sent frame data of this time and the previous frame data
stored in the blur-locus storing memory-cum-plural image storing
memory 210. The calculated blur-locus is stored in the blur-locus
storing memory-cum-plural image storing memory 210.
After the exposure is completed, the control CPU 204 controls the
image pick-up element driving portion 202 so that the destructive
read-out of all of the pixels P of the image pickup element 203
is performed, and also controls the switching portion 208 so as
to send the pixel data to the blur-compensation portion 211.
The pixel data obtained by the destructive read-out of all of the
pixels P in the image pick-up element 203 is converted into digital
data by the A/D converter 205, and sent to the blur-compensation
portion 211 through the switching portion 208.
In the blur-compensation portion 211, the image data obtained by
the aforementioned destructive read-out is subjected to the blur-compensation
processing and/or the blur-restoration processing using the blurring
locus data from the blur-locus storing memory-cum-plural image storing
memory 210. Then, the image data after the blurring compensation
and/or the blurring restoration is sent to the image memory 212,
and then stored in the recording media 213.
The terms and descriptions in this specification are used only
for explanatory purposes and the present invention is not limited
to these terms and descriptions. It should be appreciated that there
are many modifications and substitutions without departing from
the spirit and the scope of the present invention which is defined
by the appended claims.
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