JPH04320178A - Digital electronic still camera operation thereof device and method for reproducing digital picture - Google Patents

Abstract

PURPOSE:To compress a data and to record the compressed data in a memory card by using data compression circuits 18, 19 for a low picture element even when a CCD 12 for high picture elements to pick up an object. CONSTITUTION:A picture data by one frame is split so that part of a picture area is overlapped, two split picture data are compressed respectively separately at compression expansion circuits 18,19 and the result is recorded in a memory card 30. A split compression picture data read from the memory card 30 is expanded separately by the compression expansion circuits 18, 19. An averaging circuit 25 takes arithmetic mean to the expanded picture data of the overlapped part. Thus, a distortion which might appear at a border of reproduced pictures is prevented in this way.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital electronic still camera and method of operation thereof, and a digital image reproduction apparatus and method.

0002

2. Description of the Related Art A conventional digital electronic still camera uses a CCD with approximately 400,000 pixels as a means for photographing a subject. The analog video signal obtained from this CCD is converted into digital image data, subjected to data compression processing, and recorded on a recording medium such as a memory card.

0003

[Problems to be Solved by the Invention] A CCD with 400,000 pixels cannot be said to have a sufficiently high resolution. In recent years, the number of pixels in CCDs has increased, and high-resolution CCs with 800,000 pixels or more have become available.
I'm starting to get D. Therefore, it is conceivable to use a CCD with approximately 800,000 pixels in order to obtain a high-resolution photographed image.

A data compression/expansion circuit built into a digital electronic still camera is constructed from an LSI. This LSI is made to fit a 400,000 pixel CCD, so the image sensor can be changed from a 400,000 pixel CCD to an 80,000 pixel CCD.
When changing to a 800,000 pixel CCD, an 800,000 pixel CCD
This LS is used for data compression of image data obtained from
Therefore, a new LSI for data compression for an 800,000-pixel CCD must be developed.

[0005] The present invention is capable of compressing image data obtained from a high-pixel solid-state electronic image sensor using a data compression circuit for low-pixel data even when photographing a subject using a high-pixel solid-state electronic image sensor. The purpose is to make it possible.

Another object of the present invention is to prevent image quality from deteriorating when a reproduced image is obtained by decompressing image data compressed as described above.

[0007]

SUMMARY OF THE INVENTION The present invention provides a digital electronic still camera and method of operation thereof.

The digital electronic still camera according to the present invention includes a photographing means for outputting image data representing a photographed subject image, an image memory for storing image data obtained from the photographing means, and an image stored in the image memory. A data compression circuit that separately compresses the image data of each divided area when the image area represented by the data is divided into multiple areas such that the number of pixels is such that the data can be compressed and adjacent portions overlap; The apparatus includes means for recording image data compressed by the data compression circuit onto a recording medium.

The operating method of a digital electronic still camera according to the present invention includes a data compression circuit that compresses image data output from an imaging means, and the number of pixels of the imaging means is such that the number of pixels of the imaging means can be processed by the data compression process of the data compression circuit. This is a method of operating a digital electronic still camera that has more pixels than the average number of pixels. The operating method according to the present invention temporarily stores image data output from the imaging means in an image memory,
When image data is read from the image memory and subjected to data compression processing by the data compression circuit, the image area represented by the image data has a number of pixels that can be compressed by the data compression circuit, and adjacent portions overlap. The image data is divided into a plurality of areas, the image data of each divided area is compressed separately, and the compressed image data is recorded on a recording medium.

[0010] A plurality of data compression circuits may be provided, and these data compression circuits may compress the image data of the plurality of divided areas, respectively, or one data compression circuit may compress the image data of the plurality of divided areas. The data may be compressed sequentially in a time-sharing manner.

The present invention also provides a digital image reproduction apparatus and method.

[0012] In the digital image reproducing device according to the present invention, an image area of one frame is divided into a plurality of areas such that adjacent portions overlap, and image data representing each divided area is separately compressed and recorded. means for reading the compressed image data from the recording medium; a data decompression circuit for separately decompressing the read image data of each divided area; an arithmetic mean calculation means for taking an arithmetic mean of the image data; and an arithmetic mean calculation means for calculating an arithmetic mean from the image data obtained by removing the image data of the adjacent portion from the image data of each divided area after data expansion, and the image data obtained by the arithmetic mean. It is provided with means for creating and outputting image data representing a reproduced image of a piece.

In one embodiment of the invention, the digital image reproduction device is a digital electronic still camera with reproduction capability. In this digital electronic still camera, the data expansion circuit is implemented as a data compression and expansion circuit.

In the digital image reproduction method according to the present invention, an image area of one frame is divided into a plurality of areas such that adjacent parts overlap, and image data representing each divided area is separately compressed and recorded. The compressed image data is read from the recording medium, the read image data of each divided area is expanded separately, and the image data of adjacent overlapping portions of the expanded image data are added. Image data representing one frame of a reproduced image is created from the image data obtained by taking the average and decompressing the image data of the adjacent portions from the image data of each divided area, and the arithmetic averaged image data. It is.

[0015] A plurality of data expansion circuits may be provided and these data expansion circuits may be used to expand the image data of the plurality of divided areas, or one data expansion circuit may be used to expand the image data of the plurality of divided areas. The image data of the divided areas may be expanded in a time-division manner.

[0016]

[Operation] In the digital electronic still camera and its operating method according to the present invention, the number of pixels of the imaging means is
The number of pixels is greater than the number of pixels that can be compressed by a data compression circuit that compresses image data output from this imaging means.

[0017] When the image data output from the imaging means is subjected to data compression processing by the data compression circuit,
The image area represented by the image data is divided into multiple areas with the number of pixels that can be compressed by the data compression circuit and adjacent areas overlap, and the image data of each divided area is compressed separately. do. In this way, the compressed image data is recorded on the recording medium.

In the digital image reproducing apparatus and method according to the present invention, a reproducing operation is performed using image data recorded on a recording medium by the digital electronic still camera. That is, the image area of one frame is divided into a plurality of areas such that adjacent portions overlap, and the image data representing each divided area is separately subjected to data compression processing and recorded on the recording medium.

The compressed image data is read from the recording medium, and the read image data of each divided area is individually expanded. An arithmetic average of overlapping adjacent portions of image data of the expanded image data is taken. Then, image data representing one frame of the reproduced image is created from the image data obtained by removing the image data of the adjacent portions from the image data of each divided area after data expansion, and the arithmetic averaged image data.

[0020]

As described above, the present invention is applied to a digital electronic still camera in which the number of pixels of the image pickup means is greater than the number of pixels that can be compressed by the data compression circuit. Therefore, according to the present invention, even when photographing a subject using a solid-state electronic image sensor with a high number of pixels, it is possible to divide the image data obtained from the solid-state electronic image sensor into image data with a lower number of pixels. This makes it possible to compress data using a data compression circuit for low pixels.

In the data compression circuit of a digital electronic still camera, the compression ratio is often determined based on the activity of the subject image so that the compressed image data always has a constant length. Therefore, when the area of the subject image is divided into multiple areas, the activity may differ in each divided area, and the data compression rate may differ. If image data with different compression ratios are decompressed and then combined to form a single image,
In the reproduced image, a difference in image density clearly appears at the boundary between the divided areas, causing distortion.

In the digital electronic still camera and its operating method according to the present invention, one frame of image area is divided such that adjacent parts of the divided areas overlap.

According to the digital image reproducing apparatus and method according to the present invention, the arithmetic mean of the expanded digital image data is calculated for these overlapping adjacent portions. In this way, the boundaries of the divided areas are smoothly connected, distortion at the boundaries is eliminated, and differences in image density become less noticeable.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, and is a block diagram showing the electrical configuration of a digital electronic still camera with a playback function. FIG. 2 schematically shows changes in image data subjected to compression processing, and FIG. 3 schematically shows changes in image data subjected to decompression processing.

The digital electronic still camera 1 shown in FIG. 1 is connected to a memory card 30 for recording compressed image data of photographed subject images and a monitor display device 31 for visually displaying reproduced subject images. ing. The monitor display device 31 may also serve as a view finder included in the digital electronic still camera 1, or may be a device separate from the camera 1 for image reproduction.

In the digital electronic still camera 1, the entire operation of the camera is supervised by a control device 10.

The digital electronic still camera 1 includes an imaging lens 11, a CCD 12 that outputs an analog video signal representing an object image, a color balance adjustment for the analog video signal,
A signal processing circuit 13 that performs processing including gamma correction, etc., and an A/D that converts analog video signals into digital image data.
A conversion circuit 14, a frame memory 16 that stores digital image data, and a Y/C processing circuit 17 that creates luminance image data Y and color image data C from the digital image data.
, compression/expansion circuits 18 and 19 for performing data compression/expansion and encoding/decoding, an averaging circuit 25 for taking the arithmetic mean of image data, and a monitor display device 3 for displaying the subject image.
1 is provided with a circuit 26 for performing reproduction processing for visual display.

The object image is captured by the CCD by the imaging lens 11.
The image is formed on 12 planes. For example, the CCD 12 is vertically 488
It is an element with 1536 pixels horizontally, and has approximately 800,000 pixels. An analog video signal representing a subject image is output from the CCD 12 in response to depression of a shutter release button (not shown).

The analog video signal output from the CCD 12 is given to a signal processing circuit 13. Signal processing circuit 13
includes a color balance circuit and a gamma correction circuit,
Color balance adjustment and gamma correction are applied to the input analog video signal. In particular, gamma correction of the video signal narrows the dynamic range, so the next stage A/
The number of bits of the D conversion circuit 14 can be reduced.

The analog video signal output from the signal processing circuit 13 is applied to an A/D conversion circuit 14, where it is converted into digital image data. This one frame worth of digital image data is stored in the frame memory 1 by the controller 15.
6 and is temporarily memorized. This frame memory 1
6 is capable of storing image data of 800,000 pixels or more.

The image data once stored in the frame memory 16 is applied to the Y/C processing circuit 17, where brightness data and color data are generated. The generated luminance data and color data are given to the frame memory 16 again.

An example of one frame of image data stored in the frame memory 16 is shown in FIG. 2(A). This image data is divided in the horizontal direction into two areas of image data P1 and P2, left and right. The two left and right divided areas partially overlap in their adjacent parts. The image data of this overlapping portion is represented by P3. The image data P1 of one divided area consists of image data P1a excluding the overlapping part and image data P3 of the overlapping part. Similarly, the image data P2 of the other divided area consists of image data P2a excluding the overlapping portion and image data P3 of the overlapping portion.

[0033] Such image data has an overlapping part P3
are rearranged on the frame memory 16 so that they are separately included in the respective divided area image data P1 and P2 (see FIG. 2(B)). The image data may be divided and rearranged as described above before the Y/C processing, and then the Y/C processing may be performed, or the image data may be divided and rearranged after the Y/C processing.

The length in the horizontal direction of the overlapping portion of the divided area image data P1 and P2 is preferably about the length of one to several blocks, assuming that one block, which is a unit of compression processing to be described later, is 8×8 pixels.

The two divided area image data of the frame memory 16 are respectively read out by the controller 15, and one of the divided area image data P1 is read out by the compression/expansion circuit 18.
Then, the other divided area image data P2 is compressed and expanded by the compression/expansion circuit 1.
9 respectively. As the compression/expansion circuits 18 and 19, circuits manufactured to correspond to a conventional 400,000 pixel CCD can be used. Since such a compression/expansion circuit is generally capable of compressing/expanding image data of approximately 600,000 pixels, divided area image data P1 including overlapping portions
, or P2 compression and decompression processing is possible.

These two divided area image data are subjected to DCT (Di
Screte Cosine Transform)
At the same time as being converted, the data is compressed by Huffman encoding. As shown in FIG. 2(C), the divided area image data P1 is compressed and becomes compressed image data C1.
Thus, the divided area image data P2 is compressed to become compressed image data C2. Compressed image data C1, C2
, compressed image data C1 unique to each divided area are respectively stored.
a, C2a (corresponding to image data P1a, P2a, respectively), compressed image data C31,
Contains C32. These compressed image data C1 and C
2 are recorded in the memory card 30 in association with each other.

The camera shown in FIG. 1 can read data recorded on the memory card 30 and reproduce images.

Two divided compressed image data C1 and C2 constituting one frame of image recorded on the memory card 30 are read from the memory card 30 (see FIG. 3(A)), and one of the compressed image data C1 and C2 is read out from the memory card 30 (see FIG. 3(A)). The image data C1 is applied to a compression/expansion circuit 18, and the other compressed image data C2 is applied to a compression/expansion circuit 19. These divided compressed image data C1 and C2 are decoded and inversely DCT-transformed in compression/expansion circuits 18 and 19, respectively. As a result, as shown in FIG. 3(B), compressed image data C1 is expanded to become expanded image data L1, and compressed image data C2 is expanded to become expanded image data L2. The decompressed image data L1 and L2 include:
Compressed image data C1a and C unique to each divided area
In addition to image data L1a and L2a expanded from 2a, image data L31 and L32 expanded from compressed image data C31 and C32 of the overlapping area are included, respectively. Preferably, the expanded image data L3 of one of the overlapping areas is stored in the frame memory 16 as shown in FIG.
1 is rearranged so that only 1 is located between both image data L1a and L2a.

Among the divided area expanded image data L1 and L2 stored in the frame memory 16, overlapping portions of expanded image data L31 and L32 are stored in the frame memory 16.
One pixel is read out from each pixel and given to the averaging circuit 25, and the arithmetic average thereof is calculated.

The averaging circuit 25 is connected to the frame memory 16.
Latch circuits 21 and 22 temporarily latch the overlapping portion decompressed image data L31 and L32 in the two divided areas read out from each pixel data, respectively, and the arithmetic average of the image data latched by these latch circuits 21 and 22. The arithmetic mean circuit 23 consists of an arithmetic mean circuit 23 that takes the calculation results, and a latch circuit 24 that latches the calculation results of the arithmetic mean circuit 23.The arithmetic mean is calculated for one pixel data every clock, and the arithmetic mean is stored in the frame memory 16 again. It is stored as partial image data L3. In this way, one frame's worth of expanded image data is obtained, which is made up of image data L1a, L2a specific to the divided areas, and overlapping partial image data L3 placed between them.

[0041] This expanded image data is applied to the reproduction processing circuit 26, where it is converted into an analog video signal and visually displayed on the monitor 31. The reproduction processing circuit 26 includes a D/A conversion circuit, an amplifier circuit, and the like.

In the above-described embodiment, the image area is divided horizontally into two to perform data compression, but it may also be divided vertically as shown in FIG. 4, or as shown in FIG. It may also be divided into two in each of the horizontal and vertical directions, for a total of four divisions. Here, overlapping parts are hatched.

Furthermore, in the above embodiment, two compression/expansion circuits 18 and 19 are provided, and the divided image data is compressed/expanded using these two compression/expansion circuits 18, 19, respectively. It is also possible to perform compression/expansion processing using a compression/expansion circuit. At this time, the two divided image data are compressed and expanded in a time-sharing manner.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a part of the electrical configuration of a digital electronic still camera, showing an embodiment of the present invention.

FIGS. 2A to 2C show compression processing of image data divided into two parts.

FIGS. 3A to 3C show expansion processing of image data divided into two parts.

FIG. 4 is a diagram showing another method of dividing an image area.

FIG. 5 is a diagram showing still another method of dividing an image area.

[Explanation of symbols]

1 Digital electronic still camera 10 Control circuit 15 Memory controller 16 Frame memory 18, 19 Compression/expansion circuit 25 Averaging circuit

Claims (11)

[Claims] 1. Photographing means for outputting image data representing a photographed subject image, an image memory for storing image data obtained from the photographing means, and an image area represented by the image data stored in the image memory, comprising: A data compression circuit compresses the image data of each divided area separately when the image data is divided into multiple areas so that the number of pixels is compressible and adjacent areas overlap, and the data is compressed by the data compression circuit described above. A digital electronic still camera equipped with a means for recording image data on a recording medium. 2. The digital electronic still camera according to claim 1, further comprising a plurality of data compression circuits each compressing image data of a plurality of divided regions. 3. The digital electronic still camera according to claim 1, wherein said data compression circuit compresses image data of a plurality of divided areas in a time-division manner. 4. A digital electronic still camera, comprising a data compression circuit that compresses image data output from an imaging means, wherein the number of pixels of the imaging means is greater than the number of pixels that can be compressed by the data compression circuit. This is an operating method in which the image data output from the imaging means is temporarily stored in an image memory, and when the image data is read from the image memory and subjected to data compression processing by the data compression circuit, the image data represented by the image data is The image area is divided into multiple areas with the number of pixels that can be processed by data compression processing by the data compression circuit, and adjacent areas overlap, and the image data of each divided area is compressed separately. A method of operating a digital electronic still camera that records image data on a recording medium. 5. The method of operating a digital electronic still camera according to claim 4, wherein a plurality of data compression circuits are provided, and each of the image data of the plurality of divided areas is compressed by the data compression circuits. 6. The method of operating a digital electronic still camera according to claim 4, wherein image data of a plurality of divided areas is sequentially compressed in a time-division manner by one data compression circuit. 7. The image area of one frame is divided into a plurality of areas such that adjacent parts overlap, and the image data representing each divided area is compressed and recorded from a recording medium. a data decompression circuit that separately decompresses the read image data of each divided area, and an arithmetic average of overlapping image data of adjacent portions of the decompressed image data. image data representing a reproduced image of one frame from the image data obtained by removing the image data of the adjacent portion from the image data of each divided area after data expansion, and the image data subjected to the arithmetic mean. A digital image reproducing device equipped with means for creating and outputting images. 8. The digital image reproducing apparatus according to claim 7, further comprising a plurality of data decompression circuits that decompress image data of a plurality of divided areas. 9. The digital image reproducing apparatus according to claim 7, wherein the data expansion circuit expands the image data of a plurality of divided areas in a time-division manner. 10. The digital image reproducing apparatus according to claim 7, which is a digital electronic still camera having a reproducing function, and wherein said data expansion circuit is a data compression/expansion circuit. 11. The image area of one frame is divided into a plurality of areas such that adjacent parts overlap, and the image data representing each divided area is separately compressed and recorded from a recording medium. The image data of each read divided area is data-expanded separately, and the arithmetic average of the overlapping adjacent portions of the expanded image data is calculated. A digital image reproduction method that creates image data representing one frame of a reproduced image from image data obtained by removing the image data of the adjacent portion from the image data of each divided area and the arithmetic averaged image data.