JPH02179086A - Electronic still camera system - Google Patents

Abstract

PURPOSE:To display a satisfactory image without generating flicker even in the case of performing reproduction repeatedly by finding the quantity of deviation between field images from the correlation of virtual frame images on which field interpolation is applied, and correcting deviation between the field images. CONSTITUTION:Two sheets of field images of electronic still image are stored in odd and even field memories 11 and 12 for them, and a field interpolation processing is applied independently on each of the images by interpolation processing parts 13 and 14, respectively, then, the virtual frame images are generated. Those two virtual frame images are supplied to a correlation arithmetic part 15, and the quantity of deviation between the image of odd field and that of even field is detected. The quantity of deviation between the virtual frame images is recognized as that between the two sheets of field images, and the deviation correction processing of the images is performed at an image reconfiguration part 16. In other words, the deviation between the images can be corrected by reading out the image of even field stored in the memory 12 to the reconfiguration part 16, and writing the image of even field at a position where the deviation is corrected in a field memory 17 under the control of the reconfiguration part 16.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention corrects the r deviation between two field images obtained in a field sequential manner from a solid-state image sensor that electronically captures an object image, thereby eliminating flicker. This invention relates to an electronic still camera system that can obtain frame images.

[Prior Art] Recently, instead of still cameras using so-called silver halide films, electronic still image signals captured electronically using solid-state imaging devices such as COD are recorded on floppy disks, memory cards, etc. A solid-state imaging device that displays this recorded image on a TV monitor or the like is called an electronic still camera and is attracting attention. According to this type of electronic still camera (solid-state imaging device), unlike recording still images using silver halide film, it is possible to easily monitor captured images (still images) without performing film development processing or the like. It also has excellent features such as being able to be used as is for image data communication in news organizations and the like.

By the way, as a method of electronically capturing a subject image using a solid-state imaging device, there are two methods: a method of directly obtaining a single frame image from the solid-state imaging device to be used for image reproduction (display) on a TV monitor, and a method using a solid-state imaging device. There is a method in which two field images (an odd field image and an even field image to be used for image reproduction on a TV monitor) are obtained in a frame-sequential manner. This method of obtaining two field images in a field-sequential manner essentially doubles the number of pixels compared to obtaining frame images directly from a solid-state image sensor. ), it has the excellent feature of being able to effectively utilize the number of pixels of the solid-state image sensor to obtain extremely fine, high-quality electronic still images.

[Problems to be Solved by the Invention] However, when obtaining two field images from a solid-state imaging probe in a field-sequential manner, it is undeniable that a slight time lag occurs in the imaging timing of these field images. This temporal shift generally tends to cause a shift in subject images between the two field images. Particularly when the subject is moving, the image shift becomes noticeable.

This kind of shift between field images is hardly a problem in the case of movie images, but in the case of electronic still images, these two field images are repeatedly played back and output alternately. Since an image is to be displayed, a shifted portion of the image is likely to appear as flicker. Such flicker not only makes the displayed image very difficult to see, but also causes a reduction in the quality of the reproduced image.

The present invention has been made in consideration of these circumstances, and its purpose is to effectively generate flicker-free, high-quality frame images from two field images obtained from a solid-state image sensor in a field-sequential manner. The objective is to provide an electronic still camera system that can be obtained.

[Means for Solving the Problems] The electronic still camera system according to the present invention includes: (i) photoelectrically converting a subject image formed through an imaging optical system to accumulate signal charges corresponding to the amount of light of the subject image; Field interpolation is applied to each of the two field images obtained from the solid-state image sensor in a field-sequential manner, and the amount of deviation between the two field images is determined from the correlation between these interpolated two temporary frame images. (2) Then, after correcting the image shift between the two field images according to the determined amount of image shift, (2) combining these two field images with the corrected shift to obtain a frame image. It is characterized by the following.

In particular, the correlation calculation for determining the amount of deviation is performed for each area in which the field image is divided into blocks of a predetermined size, and the deviation correction is performed for each divided block area. It is.

[Function] According to the electronic still camera system according to the present invention configured as described above, the deviation between two field images obtained from the solid-state image sensor in a field-sequential manner is determined by field interpolation of each of these field images. The image deviation between the two field images is calculated from the correlation between the two processed temporary frame images, and the image deviation between the two field images is corrected according to the amount of deviation calculated from this correlation. Since a frame image is obtained by combining field images, it is possible to obtain a high-quality frame image free from flicker due to image shift caused by temporal shift.

In addition, by performing the above-mentioned deviation correction for each area in which the field image is divided into blocks of a predetermined size, it is possible to effectively correct only the image parts where flicker is noticeable, without needlessly applying deviation correction to the entire image. It becomes possible to perform deviation correction.

[Embodiment] An electronic still camera system according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an image shift correction circuit section having a characteristic processing function in the embodiment system. In this embodiment system, a solid-state image sensor such as a CCD is installed in an image sensor 1, as shown in FIG.
Then, the two field images inputted by the image capturing unit 1 and obtained in a field sequential manner are recorded on a memory card 2 as a predetermined recording medium, and the two field images recorded on the memory card 2 are It is configured to display an electronic still image consisting of images on an image monitor 3 such as a TV receiver.

That is, the two field images read out from the imaging unit I in a field-sequential manner consist of an odd field image and an even field image for image display by so-called interlaced scanning, and one set of image data (¥4 child still image). ). These two field images are each subjected to predetermined signal processing such as gamma correction in the signal processing unit 4, and then converted to digital image data with a predetermined number of bits in the A/D converter 5. be done. This A/D conversion process is basically performed for each pixel constituting the input field image.

For the two field images digitized in this way, the encoding write circuit 6:,! The data is compressed by block encoding or the like and recorded on the memory card 2. The electronic still images are recorded on the memory card 2 by, for example, assigning a photographing frame number to each field image and managing the photographed images individually.

On the other hand, the electronic still images recorded on the memory card 2 are selectively read out in units of the above-mentioned two field images under the control of the readout decoding circuit 7, and decoded by the readout decoding circuit 7. .

This decoding process is performed to restore the field image data to the original field image data, since the field image is compressed by block encoding or the like and recorded on the memory card 2 as described above.

Therefore, the inter-field motion detection section 8 and the image correction section 9
constitutes the image shift correction circuit section shown in FIG. The image correction unit 9 is configured to perform correction processing to remove the deviation according to the amount of deviation determined. The two field images whose deviations have been corrected in this way are output to the image monitor 3 via the D/A converter 310.
It is converted into an SC system TV image signal and used for image display. In other words, two field images (odd field image and even field image) are read from memory card 2.
When performing interlaced scanning and displaying an image as one frame image using It is used for image display.

Next, the detection of a shift between field images by the inter-field motion detection section 8 and the image shift correction processing by the image correction section 9 will be described in more detail.

As shown in FIG.
It is provided with an odd field image memory 11 and an even field image memory 12, each of which stores two field images. Two field images of the electronic still image captured by the electronic still camera and provided for image display on the image monitor 3 are stored in the odd field image memory 1.
．． 1 and even field image memory 12, respectively.

Therefore, the interpolation processing units 13 and 14 independently perform field interpolation processing on the odd field images and even field images stored in the odd field image memo January 1 and the even field image memory 12, respectively, and create a temporary frame. Creating an image. Specifically, as shown in FIG. 3(a), the interpolation processing unit 3 performs predetermined interpolation calculation processing on the even field image signal components between the lines from the odd field image signal shown by the solid line, for example, the correspondence between lines. A temporary frame image based on an odd field image is obtained by weighted averaging processing of pixel signals at pixel positions as shown by the broken line. Similarly, as shown in FIG. 3(b), the interpolation processing unit 14 calculates the odd field image signal components from the even field image signals shown by the solid line by performing predetermined interpolation calculation processing as shown by the broken lines, and bases the even field image on the even field image signal. We are looking for a temporary frame image.

The two temporary frame images obtained in this manner are provided to the correlation calculating section 15 and used for detecting image deviation between the odd field image and the even field image. For example, as shown in FIG. 4, the correlation calculation unit 15 sets a comparison reference point A in one image as a reference, and sets a comparison reference point A in the other image so as to surround the points corresponding to the comparison reference point A. Set area B. Then, this comparison reference area B is scanned to check the correlation between each scan point and the comparison reference point A, and the scan point with the highest correlation value is set as the comparison point C for measuring the amount of image shift. By determining the amount of deviation between this comparison point and the comparison reference point, the amount of image deviation (vector D indicated by an arrow in the figure) is measured.

Note that it is also possible to set a plurality of comparison reference points and measure the amount of deviation of this image for each of these comparison reference points. In addition, a comparison reference area of a predetermined size is set in place of the comparison reference point, and the comparison reference area surrounding this comparison reference area is scanned to find the area that has the highest correlation with the comparison reference area. It is also possible to calculate the amount of deviation.

Furthermore, as shown in FIG. 5, it is also possible to divide the image area into blocks of a predetermined size and calculate the image shift for each of these divided block areas.

In addition, the correlation calculation described above can be performed by, for example, calculating the pixel data set as a comparison reference point for an odd field image by f, and the above ratio (x) for an even field image. It is sufficient to search for the point where φ is the minimum by calculation.

Alternatively, we can introduce a dispersion method and detect the point where V is the minimum by the calculation Bef(×)(x・[)>2 g as the corresponding point with the highest correlation (S). Good. However, in the above formula, 〉 is an operator that represents the average value.

The amount of deviation between the temporary frame images obtained as described above is taken as the amount of deviation between the two field images described above, and the image reconstruction section 1B performs deviation correction processing on the image. In this embodiment, since the amount of deviation of the even field image is calculated using the odd field image as a reference, the even field image stored in the even field image memory 12 is read out to the image reconstruction unit 1B, and the image reconstruction unit Field image memory 1 under the control of part IB
The image shift is corrected by writing the even field image at the position where the shift has been corrected.

Regarding the deviation correction by reconstructing this even field image, it is possible to correct the deviation of the entire image at once according to the amount of image deviation determined at the representative point, but as described above, it is possible to correct the deviation of the entire image at once for each of multiple comparison reference points. When the amount of deviation is calculated for each area divided into blocks as shown in FIG. 5, the deviation should be corrected for each part of the image. is also possible. It is also possible to perform control so that the deviation is corrected only for the image portion where the deviation is particularly large.

In this way, the field image memory 11 is stored with deviation correction (
By displaying an image by interlace scanning using the even field image stored after reconstruction and the odd field image stored in the odd field image memory 11, flicker caused by image shift can be reduced. It becomes possible to obtain a frame image that does not have a frame image.

Thus, according to the present system equipped with the above-mentioned field image shift correction circuit, since two field images are obtained in a field sequential manner, an image shift occurs due to the temporal shift, and this image Even if the deviation causes flicker during still image reproduction, this flicker can be effectively removed. In particular, when partial deviation correction is performed only on the image part where the image deviation has occurred, in order to prevent flicker from occurring due to the deviation of a part of the image, it is necessary to prevent new flicker from occurring in another image part. This will not cause any problems that may otherwise occur. In other words, by correcting the shift only for the moving part of the subject image, it is possible to prevent flicker from occurring without adversely affecting the entire image.

Note that the present invention is not limited to the embodiments described above. Here, we have explained an example in which misalignment correction is applied to a field image recorded on a memory card. It is also possible to construct the system so that the images are recorded on a computer or displayed on an image monitor. Furthermore, the algorithm for detecting the amount of image shift using correlation calculation and the method for correcting image shift based on the detected amount of shift may be determined according to the system specifications, and the point is that the present invention deviates from the gist thereof. It can be implemented with various modifications within the scope.

[Effects of the Invention] As explained above, according to the present invention, the amount of deviation between field images is determined from the correlation of field-interpolated temporary frame images and the deviation between the field images is corrected. Even when electronic still images are repeatedly reproduced using this method, great practical effects such as good flicker-free image display can be achieved.

[Brief explanation of the drawing]

The figures show an electronic still camera system according to an embodiment of the present invention. Fig. 1 is a schematic configuration diagram of an image shift correction circuit section that exhibits a characteristic processing function in the embodiment system, and Fig. 2 shows an implementation of the system. A diagram showing an example of the overall configuration of an example system,
FIG. 3 is a diagram for explaining field interpolation processing for field images, and FIGS. 4 and 5 are diagrams for explaining shift detection between field images. 1... Imaging unit, 2... Memory card, 3... Image monitor, 8... Inter-field motion detection unit, 9... Image correction unit, 1.1... Odd field image memory, 1
2... Even field image memory, 13.14...
Interpolation processing unit, 15... Correlation calculation unit, l... Image reconstruction unit, 17... Field image memory. Applicant's agent Patent attorney Jun Tsuboi 2rlli

Claims (2)

[Claims] (1) means for obtaining two field images in a field-sequential manner from a solid-state image sensor that photoelectrically converts a subject image formed through an imaging optical system and accumulates signal charges according to the amount of light of the subject image; A means for independently performing field interpolation processing on the two field images obtained in this field sequential manner to obtain temporary frame images, and a means for determining the deviation between the two field images from the correlation between these temporary frame images. a correlation calculating unit for calculating the amount of image deviation; a means for correcting the image deviation between the two field images according to the amount of image deviation determined by the correlation calculating unit; An electronic still camera system characterized by comprising means for synthesizing and obtaining frame images. (2) A correlation calculation unit that calculates the amount of deviation between the two interpolated field images from the correlation between the two interpolated field images,
A field image is divided into blocks of a predetermined size, and the amount of image deviation is calculated for each area, and the means for correcting the image deviation between two field images is as follows:
Claim (1) wherein the deviation is corrected for each image area corresponding to the block divided area for which the amount of deviation has been determined.
The electronic still camera system described in Section 1.