JP2012105031A - Image compression device, image decompression device, method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce costs by reducing the number of encoders to be used to compress two or more images which have to be compressed with different compressibility ratios.SOLUTION: Region-of-interest detection means 12 detects a region of interest from an image to be processed 101 to generate a region-of-interest image 103. Image decompression means 13 generates a decompressed image 102 by decompressing the image size of the image to be processed 101. Multiplexing means 14 generates a multiplexed image 104 by multiplexing the decompressed image 102 and the region-of-interest image 103 on an image space. Compression means 15 generates compressed image data 106 by compressing the multiplexed image 104.

Description

  The present invention relates to an image compression apparatus, method, and program, and more specifically, an image compression apparatus that extracts a region of interest from an image and compresses the image with a difference in image quality between the region of interest and the non-interest region, The present invention relates to a method and a program. The present invention also relates to an image decompression apparatus, method, and program for decompressing a compressed image.

  A technique is known in which a feature region is extracted from an image, the image is divided into a feature region and a background region other than the feature region, and the feature region image and the background image are compressed with different strengths (see, for example, Patent Document 1). ). In Patent Document 1, a feature area image is extracted from a plurality of moving image composition images, and a feature area compression moving image and a background area compression moving image are generated. The feature region compression moving image is compressed by a compression unit corresponding to the compression of the feature region to generate the feature region moving image data, and the background region compression moving image is compressed by the compression unit corresponding to the compression of the background region. Generate area video data. The feature area moving image data and the background area moving image data are associated with each other, for example, by attaching tag information or the like, and are output via the communication network.

JP 2009-49979 A

  In Patent Literature 1, separate compression units are used for the compression of the feature region compression moving image and the background region compression moving image. In Patent Document 1, it is necessary to provide as many compression units as the number of moving images to be compressed, and there is a problem that the cost of the circuit increases by the provision of a plurality of compression units. In Patent Document 1, feature area moving image data and background area moving image data are generated separately. Since the feature area moving image data and the background area moving image data are generated as separate streams, in order to obtain the original moving image, it is necessary to manage both in association with each other, and there is a problem that management is troublesome.

  In view of the above, the present invention provides an image compression apparatus, method, and program capable of reducing the cost by reducing the number of encoders used when compressing two or more images to be compressed by changing the compression rate. With the goal.

  In order to achieve the above object, the present invention provides an image reduction means for generating a reduced image obtained by reducing the image size of an input processing target image, a region of interest from the processing target image, and the processing target image. Region-of-interest detection means for generating a region-of-interest image obtained by extracting the detected region of interest, multiplexing means for generating a multiplexed image obtained by multiplexing the reduced image and the region-of-interest image on an image space, and the multiplexing There is provided an image compression apparatus comprising compression means for generating compressed image data obtained by compressing the multiplexed image generated by the conversion means.

  In the present invention, the image multiplexing unit may multiplex the reduced image and the region-of-interest image in different regions of the multiplexed image.

  The multiplexing unit may multiplex the images by arranging the reduced image above the image of the multiplexed image and arranging the region of interest image below the image of the multiplexed image.

  The image compression apparatus of the present invention is based on the compressed image data, the partial image decompression unit that decompresses the reduced image portion in the multiplexed image compressed by the compression unit, and the decompressed by the partial image decompression unit. Enlarging means for enlarging the reduced image portion to the image size of the processing target image, and the reduced image portion and the region of interest image enlarged by the enlarging means for a position corresponding to the region of interest in the processing target image A difference image generation means for generating a difference image of the image, wherein the compression means starts compression from the upper part of the image of the multiplexed image, and temporarily stops the compression when the compression of the reduced image portion is completed, The partial image decompression unit obtains temporary compressed image data obtained by compressing the reduced image from the compression unit when the compression unit compresses the reduced image portion. The reduced image portion is expanded based on the received provisional compressed image data, and the multiplexing unit arranges the difference image below the multiplexed image instead of the region-of-interest image. Thus, the reduced image and the difference image are multiplexed on the image space, and the compression unit resumes the compression of the multiplexed image after the difference image is arranged below the image of the multiplexed image. A configuration can be employed.

  The image compression apparatus according to the present invention can employ a configuration further comprising region-of-interest information adding means for adding region-of-interest information regarding the position of the detected region of interest in the processing target image to the compressed image data.

  The present invention decompresses compressed image data obtained by compressing a multiplexed image in which a reduced image obtained by reducing a processing target image and a region of interest image obtained by extracting a region of interest from the processing target image are multiplexed on an image space. The decompression unit that generates the multiplexed image, the image separation unit that separates the reduced image and the region-of-interest image from the multiplexed image generated by the decompression unit, and the separated reduced image, An image enlarging means for enlarging the processing target image, an image synthesizing means for generating a synthesized image obtained by synthesizing the reduced image enlarged by the enlarging means, and the region-of-interest image. An image decompression apparatus is provided.

  The compressed image data is added with region-of-interest information related to the position of the region of interest in the processing target image, and further comprises region-of-interest information separating means for separating the region-of-interest information from the compressed image data, A configuration may be employed in which the image composition unit generates the composite image by superimposing the region-of-interest image on the enlarged reduced image using the region-of-interest information.

  In the multiplexed image, instead of the region-of-interest image, a difference image between the image of the region-of-interest image and the image obtained by enlarging the compressed reduced image portion to the size of the processing target image is multiplexed. Separating means separates the reduced image and the difference image from the multiplexed image instead of the region of interest image, and the image synthesizing means replaces the enlarged region of interest image instead of the region of interest image. And the difference image may be combined.

  In the case of the above configuration, the image composition unit may generate the composite image by adding the difference image to the enlarged reduced image.

  The present invention provides an image reduction means for generating a reduced image obtained by reducing the image size of an input processing target image, and a region of interest is detected from the processing target image, and the detected region of interest is extracted from the processing target image Region-of-interest detection means for generating a region-of-interest image, image composition means for generating a multiplexed image obtained by multiplexing the reduced image and the region-of-interest image on an image space, and multiplexing generated by the image composition means Compression means for generating compressed image data obtained by compressing an image; decompression means for decompressing the compressed image data to generate the multiplexed image; and the reduced image and the multiplexed image generated by the decompression means. Image separation means for separating the region-of-interest image, image enlargement means for enlarging the separated reduced image to the size of the processing target image, and reduced image enlarged by the enlargement means , To provide an image decompression apparatus comprising the image synthesizing means for generating a composite image of the region of interest image.

  The present invention also includes a step of generating a reduced image in which the image size of the input processing target image is reduced, a region of interest is detected from the processing target image, and the detected region of interest is extracted from the processing target image Generating a region-of-interest image, generating a multiplexed image obtained by multiplexing the reduced image and the region-of-interest image on an image space, and generating compressed image data obtained by compressing the generated multiplexed image An image compression method comprising the steps of:

The present invention includes a step of generating a reduced image obtained by reducing an image size of an input processing target image, a region of interest detected from the processing target image, and the detected region of interest extracted from the processing target image Generating an image; and arranging the reduced image above an image of a multiplexed image for multiplexing the reduced image and the region-of-interest image on an image space, and sequentially multiplexing the image from the upper side of the image Compressing the image, and temporarily stopping compression of the multiplexed image when the reduced image portion of the multiplexed image is compressed, and based on provisional compressed image data at the stage of compressing the reduced image portion Expanding the reduced image portion,
The step of enlarging the decompressed reduced image portion to the size of the processing target image, and the difference between the enlarged reduced image portion and the region of interest image at a position corresponding to the region of interest in the processing target image Generating an image; and arranging the difference image below the multiplexed image, restarting the compression of the multiplexed image after the arrangement, and generating compressed image data obtained by compressing the multiplexed image And a second image compression method.

  The present invention decompresses compressed image data obtained by compressing a multiplexed image in which a reduced image obtained by reducing a processing target image and a region of interest image obtained by extracting a region of interest from the processing target image are multiplexed on an image space. And generating the multiplexed image, separating the reduced image and the region-of-interest image from the generated multiplexed image, and converting the separated reduced image into a size of the processing target image. And a step of generating a synthesized image obtained by synthesizing the enlarged reduced image and the region-of-interest image.

  In the present invention, a reduced image obtained by reducing a processing target image, and a difference image between the region of interest image and an image obtained by enlarging a compressed reduced image portion to the size of the processing target image are multiplexed in an image space. Decompressing compressed image data obtained by compressing a multiplexed image, generating the multiplexed image, separating the reduced image and the difference image from the generated multiplexed image, and the separated A second image decompression comprising: enlarging the reduced image to a size of the processing target image; and generating a synthesized image obtained by synthesizing the enlarged reduced image and the difference image. Provide a method.

  Furthermore, the present invention provides a computer for generating a reduced image obtained by reducing the image size of the input processing target image, detecting a region of interest from the processing target image, and detecting the detected region of interest from the processing target image. A procedure for generating an extracted region-of-interest image, a procedure for generating a multiplexed image obtained by multiplexing the reduced image and the region-of-interest image on an image space, and compressed image data obtained by compressing the generated multiplexed image The first image compression program for executing the procedure for generating the image data is provided.

  The present invention provides a computer for generating a reduced image obtained by reducing the image size of an input processing target image, detecting a region of interest from the processing target image, and extracting the detected region of interest from the processing target image. Generating a region-of-interest image, and arranging the reduced image above the multiplexed image for multiplexing the reduced image and the region-of-interest image on an image space, and sequentially from the upper side of the image A procedure for compressing the multiplexed image, and a temporary compressed image in a stage in which compression of the multiplexed image is temporarily stopped when the reduced image portion of the multiplexed image is compressed, and the reduced image portion is compressed. A procedure for expanding the reduced image portion based on the data; a procedure for expanding the expanded reduced image portion to a size of the processing target image; and a region of interest in the processing target image. For the corresponding position, a procedure for generating a difference image between the enlarged reduced image portion and the region-of-interest image, and placing the difference image below the multiplexed image, the multiplexing after the placement There is provided a second image compression program for restarting image compression and executing a procedure for generating compressed image data obtained by compressing the multiplexed image.

  The present invention provides a compressed image obtained by compressing a multiplexed image obtained by multiplexing a reduced image obtained by reducing a processing target image and a region of interest image obtained by extracting a region of interest from the processing target image in an image space. A procedure for decompressing data and generating the multiplexed image; a procedure for separating the reduced image and the region-of-interest image from the generated multiplexed image; and There is provided a first image decompression program for executing a procedure for enlarging an image to a size, and a procedure for generating a synthesized image obtained by synthesizing the enlarged reduced image and the region-of-interest image.

  According to the present invention, a reduced image obtained by reducing a processing target image, and a difference image between the region of interest image and an image obtained by enlarging a compressed reduced image portion to the size of the processing target image are multiplexed on an image space. Decompressing compressed image data obtained by compressing the multiplexed image, and generating the multiplexed image; separating the reduced image and the difference image from the generated multiplexed image; A second image for executing a procedure for enlarging the separated reduced image to the size of the processing target image and a procedure for generating a synthesized image obtained by synthesizing the enlarged reduced image and the difference image. Provide decompression program.

  The image compression apparatus, method, and program of the present invention generate a multiplexed image in which a reduced image with a reduced image size and a region-of-interest image are multiplexed on an image space, and compress the multiplexed image. In the present invention, since the reduced image to be compressed and the image of interest to be compressed with different compression ratios are multiplexed and compressed into a multiplexed image, both images can be compressed using a single compression means. Costs can be reduced by reducing the number of encoders used. The image decompression apparatus, method, and program of the present invention can decompress the compressed image by decompressing the compressed image data compressed by the image compression apparatus of the present invention.

1 is a block diagram illustrating an image compression apparatus according to a first embodiment of the present invention. 6 is a flowchart showing an operation procedure of the image compression apparatus. The block diagram which shows the specific example of the image produced | generated by each part of an image compression apparatus. 1 is a block diagram showing an image expansion device corresponding to an image compression device of a first embodiment. 6 is a flowchart showing an operation procedure of the image expansion apparatus. The block diagram which shows the specific example of the image produced | generated by each part of an image expansion | extension apparatus. The block diagram which shows the image compression apparatus of 2nd Embodiment of this invention. 6 is a flowchart showing an operation procedure of the image compression apparatus. The block diagram which shows the specific example of the image produced | generated by each part of an image compression apparatus. The block diagram which shows the image expansion | extension apparatus corresponding to the image compression apparatus of 2nd Embodiment. 6 is a flowchart showing an operation procedure of the image expansion apparatus. The block diagram which shows the specific example of the image produced | generated by each part of an image expansion | extension apparatus. The figure which shows another example of multiplexing of a reduced image and a region-of-interest image.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an image compression apparatus according to a first embodiment of the present invention. The image compression apparatus 10 includes an image input unit 11, a region of interest detection unit 12, an image reduction unit 13, a multiplexing unit 14, a compression unit (encoder) 15, a region of interest information addition unit 16, and an output unit 17. The function of each unit in the image compression apparatus 10 can be realized by a computer executing processing according to a predetermined program.

  The image input unit 11 inputs an image to be processed. The image input unit 11 inputs, for example, an image photographed using a photographing device (not shown) as a processing target image. Alternatively, the image input unit 11 may read out the processing target image from a storage device (not shown) that stores the image. The image input means 11 can sequentially input a plurality of frame images constituting a moving image.

  The region of interest detection unit 12 detects a region of interest (ROI) from the processing target image, and generates a region of interest image. Arbitrary algorithms can be used for the region of interest detection algorithm. The region-of-interest detection means 12 detects, for example, a region where a predetermined detection target object appears from the processing target image. Alternatively, the region-of-interest detection means 12 may detect a portion where there is movement between frame images as a region of interest. The resolution (image size) of the region of interest image may be the same as the resolution of the processing target image.

  The image reducing unit 13 generates a reduced image obtained by reducing the image size of the processing target image. In other words, the image reducing unit 13 generates an image in which the resolution of the processing target image is reduced to a predetermined resolution. The image reducing unit 13 generates a reduced image by thinning out pixels from the processing target image at a predetermined ratio, for example. The image reduction method is not particularly limited. The image reduction unit 13 reduces the resolution of the processing target image so that the resolution of the reduced image is lower than the resolution of the region-of-interest image.

  The multiplexing unit 14 generates a multiplexed image in which the reduced image reduced by the image reducing unit 13 and the region-of-interest image generated by the region-of-interest detection unit 12 are multiplexed on an image space. For example, the multiplexing unit 14 arranges the reduced image and the region-of-interest image in different regions of the multiplexed image. For example, the multiplexing unit 14 has the number of pixels in the horizontal direction of the image equal to the number of pixels in the horizontal direction of the region of interest image, and the number of pixels in the vertical direction is the number of pixels in the vertical direction of the reduced image and the pixel in the vertical direction of the region of interest image. An image equal to the sum of the numbers is prepared as a multiplexed image, the reduced image is arranged above the multiplexed image, and the region-of-interest image is arranged below the multiplexed image to multiplex the images.

  The compression unit 15 compresses the multiplexed image generated by the multiplexing unit 14 to generate compressed image data. The image compression format is not particularly limited. The compression means 15 is, for example, H.264. H.264 performs image compression. The region-of-interest information adding unit 16 adds region-of-interest information related to the position of the region of interest detected in the region-of-interest detection unit 12 in the processing target image to the compressed image data generated by the compression unit 15. The output means 17 outputs the compressed image data to which the region of interest information is added. The output unit 17 outputs the compressed image data to a receiving apparatus via a communication network, for example. Alternatively, the output unit 17 may output the compressed image data to a storage device such as a hard disk drive.

  FIG. 2 shows an operation procedure. The image input unit 11 inputs a processing target image (step S11). The image reducing unit 13 generates a reduced image in which the resolution of the processing target image is reduced (step S12). For example, the image reduction unit 13 generates a reduced image by halving the vertical and horizontal image sizes of the processing target image and reducing the vertical and horizontal resolutions by half. The image reducing unit 13 outputs the generated reduced image to the multiplexing unit 14.

  The region of interest detection means 12 detects the region of interest from the processing target image (step S13). The region-of-interest detection unit 12 extracts a region of interest detected from the processing target image, for example, and generates an image in which pixel values other than the extracted portion are fixed to a predetermined value, for example, 0 (black), as the region-of-interest image. The region-of-interest detection unit 12 outputs the generated region-of-interest image to the multiplexing unit 14. The region-of-interest detection unit 12 outputs region-of-interest information indicating the position of the detected region of interest in the processing target image to the region-of-interest information adding unit 16.

  The multiplexing unit 14 multiplexes the reduced image and the region-of-interest image on the image space (step S14). That is, the multiplexing unit 14 multiplexes the reduced image and the region-of-interest image into one multiplexed image. The compression unit 15 compresses the multiplexed image (step S15). The region-of-interest information adding unit 16 adds region-of-interest information to the compressed image data generated by the compression unit 15 (step S16). The output unit 17 outputs the compressed image data to which the region-of-interest information is added to the receiving side image decompression device or storage device (step S17).

  FIG. 3 shows a specific example of an image generated by each unit of the image compression apparatus 10. The input processing target image 101 is given to the region of interest detection means 12 and the image reduction means 13. The image reduction unit 13 generates a reduced image 102 by reducing the resolution of the processing target image 101. The processing target image 101 and the reduced image 102 are images representing the same content. However, the image size of the reduced image 102 is smaller than the image size of the processing target image 101.

  The region-of-interest detection means 12 detects, for example, a region constituting a person from the processing target image 101 as a region of interest, and generates a region-of-interest image 103. For example, the region-of-interest detection unit 12 converts an image in which the pixel value of the portion constituting the detected person is the same as the pixel value of the processing target image 101 and the pixel value of the portion other than the person is fixed to 0 103 is generated. In addition, the region-of-interest detection unit 12 generates region-of-interest information 105 indicating the position of the region of interest in the processing target image.

  The multiplexing unit 14 generates a multiplexed image 104 in which the reduced image 102 and the region-of-interest image 103 are multiplexed into one image. In the multiplexed image 104, the reduced image 102 is arranged at the upper part of the image, and the region-of-interest image 103 is arranged at the lower part of the image. Since the reduced image 102 has an image size smaller than that of the region-of-interest image 103, a blank portion in which the reduced image 102 is not arranged is formed above the image. The blank portion in the multiplexed image 104 may be filled with, for example, white.

  The compression unit 15 compresses the multiplexed image 104 and generates compressed image data 106. For example, when the processing target images 101 constituting the moving image are sequentially input, the multiplexing unit 14 sequentially generates the multiplexed images 104 corresponding to the processing target images 101 of the respective frames. The compression means 15 can perform image compression using the multiplexed image 104 of the previous and subsequent frames. The region-of-interest information adding unit 16 adds the region-of-interest information 105 to the compressed image data 106. The compressed image data 106 to which the region-of-interest information 105 is added is output via the output unit 17.

  Next, an image decompression apparatus that decompresses an image compressed by the image compression apparatus 10 will be described. FIG. 4 shows an image expansion apparatus corresponding to the image compression apparatus 10 of the present embodiment. The image expansion device 20 includes a data input unit 21, a region-of-interest information separation unit 22, an expansion unit (decoder) 23, an image separation unit 24, an image enlargement unit 25, an image composition unit 26, and an output unit 27. The function of each unit of the image expansion device 20 can be realized by a computer executing processing according to a predetermined program, for example.

  The data input means 21 inputs the compressed image data output from the output means 27 of the image compression apparatus 10 shown in FIG. That is, the data input unit 21 compresses a multiplexed image obtained by compressing a reduced image obtained by reducing a processing target image and a region of interest image obtained by extracting a region of interest from the processing target image in an image space. Enter the data. Region-of-interest information is added to the compressed image data.

  The region-of-interest information separating unit 22 separates the compressed image data and the region-of-interest information. The region-of-interest information separation unit 22 outputs the compressed image data to the decompression unit 23 and outputs the region-of-interest information to the image composition unit 26. The decompression unit 23 decompresses the compressed image data and generates a multiplexed image. The expansion unit 23 performs expansion using an expansion method corresponding to the compression method used by the compression unit 15 of the image compression apparatus 10.

  The image separating unit 24 separates the reduced image and the region of interest image from the multiplexed image generated by the decompressing unit 23. The image separation unit 24 outputs the separated reduced image to the image enlargement unit 25, and outputs the region of interest image to the image composition unit 26. The image enlarging means 25 enlarges the separated reduced image to the size of the processing target image. Since the image size of the region-of-interest image and the image size of the processing target image are the same size, the image size of the enlarged reduced image is the same as the image size of the region-of-interest image. The image enlargement process in the image enlargement unit 25 is the reverse of the reduction process in the image reduction unit 13 of the image compression apparatus 10.

  The image synthesizing unit 26 generates a synthesized image obtained by synthesizing the region-of-interest image and the reduced image enlarged by the image enlarging unit 25. At that time, the image composition unit 26 uses the region-of-interest information separated by the region-of-interest information separation unit 22 to generate a composite image by superimposing the region-of-interest image on the enlarged reduced image. The output means 27 outputs the composite image generated by the image composition means 26 to a display device for performing image display.

  FIG. 5 shows an operation procedure for image decompression. The data input means 21 inputs the compressed image data to which the region of interest information is added (Step S21). The data input means 21 inputs compressed image data output from the image compression apparatus 10 (FIG. 1) via, for example, a communication network. Alternatively, the data input unit 21 may read the compressed image data from the storage device.

  The region-of-interest information separating unit 22 separates the compressed image data from the region-of-interest information added to the data (step S22). The decompression unit 23 decompresses the compressed image data and restores the multiplexed image compressed by the image compression apparatus 10 (step S23). The image separation unit 24 separates the restored multiplexed image into a reduced image and a region-of-interest image (step S24). The image enlarging means 25 enlarges the reduced image to the image size of the processing target image (step S25). Super-resolution (SR) technology can be used for image enlargement. By using super-resolution, it is possible to suppress deterioration in image quality of the enlarged image.

  The image synthesizing unit 26 synthesizes the enlarged reduced image and the region-of-interest image (step S26). At that time, the image synthesizing unit 26 synthesizes an image using the region of interest information as mask information. More specifically, the image composition unit 26 cuts out only the region of interest from the region of interest image and superimposes the cut out region of interest on the enlarged reduced image. The output unit 27 outputs the composite image synthesized by the image synthesis unit 26 to a display device or the like (step S27).

  FIG. 6 shows a specific example of an image generated by each unit of the image expansion device. The compressed image data 201 is compressed image data obtained by, for example, compressing the processing target image 101 shown in FIG. The region-of-interest information separating unit 22 separates the region-of-interest information 206 added to the compressed image data 201. The decompressing unit 23 restores the multiplexed image 202 from the compressed image data 201. The contents of the multiplexed image 202 are the same as those of the multiplexed image 104 in FIG. However, there is a portion where the image quality is not exactly the same and the image quality is degraded by the amount of compression.

  The image separating unit 24 separates the reduced image 204 and the region-of-interest image 203 from the multiplexed image 202. The image enlarging means 25 enlarges the reduced image 204 and generates an enlarged reduced image 205. By enlarging the image, the image size of the enlarged reduced image 205 and the image size of the region-of-interest image 203 become the same size.

  The image synthesizing unit 26 synthesizes the enlarged reduced image 205 and the region-of-interest image 203 using the region-of-interest information 206 to generate a synthesized image 207. The image synthesizing unit 26 cuts out a portion where the person indicated by the region-of-interest information 206 appears from the region-of-interest image 203 and generates a composite image 207 by superimposing the cut-out region on the enlarged reduced image 205. In the composite image 207, the pixels of the enlarged reduced image 205 are arranged in the pixels other than the portion where the person appears, and the pixels of the region-of-interest image 203 are arranged in the pixels of the region where the person appears. The image expansion device 20 outputs a composite image 207.

  When the processing target image 101 (FIG. 3) input to the image compression apparatus 10 and the composite image 207 output from the image expansion apparatus 20 are compared, the area other than the portion constituting the person in the composite image 207 is integrally reduced. Since the image is obtained by enlarging the image, the image quality of the composite image 207 in a portion that does not constitute a person is lower than that of the processing target image 101. On the other hand, as for the portion of the region of interest, the image quality is less deteriorated than the portion that does not constitute a person because the image is not reduced.

  In the present embodiment, the multiplexing unit 14 multiplexes the region of interest image obtained by extracting the region of interest from the processing target image and the reduced image obtained by reducing the processing target image into one multiplexed image on the image space. . The compression unit 15 compresses the multiplexed image, and the output unit 17 outputs the compressed image data obtained by the compression. In this embodiment, since the region-of-interest image and the reduced image are multiplexed into one multiplexed image and the multiplexed image is compressed, it is necessary to use compression means corresponding to each of the region-of-interest image and the reduced image. Absent. The image compression apparatus 10 only needs to include one compression unit 15 for compressing the multiplexed image, and the number of necessary compression units can be reduced to reduce the cost of the circuit.

  Here, in Patent Document 1, a compression unit that compresses a moving image for feature region compression and a compression unit that compresses a moving image for background region compression are implemented by one compressor, and the moving image for feature region compression and the compression region for background region are implemented. There is a description that video can be sequentially compressed in time. However, if the feature region compression video for a certain amount of time is compressed and then the background region compression movie for the same amount of time is continuously compressed, there will be a large shift in the generation timing of both video data, resulting in real-time performance. Will be lost. In this embodiment, since the region-of-interest image and the reduced image are compressed as one multiplexed image, the image can be compressed without losing the real-time property.

  Further, in Patent Document 1, it is also conceivable to switch between a frame image constituting a feature region compression moving image and a frame image constituting a background region compression moving image and inputting them to a compressor for each frame. However, since both images are alternately input, for example, when performing image compression with reference to the preceding and following frame images in the feature region compression moving image, the compression means needs to perform image reference every other frame. There arises a problem that the reference relationship between them becomes complicated. Furthermore, there arises a problem that extra memory is required. In this embodiment, since the region-of-interest image and the reduced image are multiplexed into one multiplexed image, the image can be compressed without complicating the reference relationship between frames. Further, the compression unit 15 only needs to compress one multiplexed image, and no special interframe reference is required. Therefore, an existing compression unit can be used as the compression unit 15.

  In this embodiment, since the region-of-interest image and the reduced image are multiplexed into one multiplexed image, the region-of-interest image and the reduced image are expanded from one multiplexed image by expanding the compressed image data. Both can be obtained. In Patent Document 1, separate decompression means for decompressing each of the feature area moving image data and the background area moving image data is required. However, in the present embodiment, the number of the decompression means 23 in the image decompression apparatus 20 is one. It ’s enough. Further, in Patent Document 1, since the feature area moving image data and the background area moving image data are generated as separate streams, a multiplexer for integrating a plurality of streams on the image compression side is necessary, and a plurality of images are generated on the image expansion side. A demultiplexer was needed to separate the streams. In this embodiment, since a region-of-interest image and a reduced image are obtained from one multiplexed image, such a multiplexer or demultiplexer is unnecessary. Further, in the present embodiment, since the region-of-interest image and the reduced image are obtained from one multiplexed image in a synchronized state, there is also an effect that it is not necessary to separately associate and manage both.

  Next, a second embodiment of the present invention will be described. FIG. 7 shows an image compression apparatus according to the second embodiment of the present invention. The image compression apparatus 30 includes an image input means 31, a region of interest detection means 32, an image reduction means 33, a multiplexing means 34, a compression means 35, a partial image expansion means 36, an enlargement means 37, a difference image generation means 38, and an output means. 39. The function of each unit in the image compression device 30 can be realized by, for example, a computer executing processing according to a predetermined program.

  The image input means 31 inputs an image to be processed. The image input means 31 inputs, for example, an image shot using a shooting device (not shown) as a processing target image. Alternatively, the image input unit 31 may read out the processing target image from a storage device (not shown) that stores the image. The image input means 31 can sequentially input a plurality of frame images constituting a moving image.

  The region-of-interest detection means 32 detects a region of interest from the processing target image and generates a region-of-interest image. Arbitrary algorithms can be used for the region of interest detection algorithm. The region-of-interest detection means 32 detects, for example, a region where a predetermined detection target object appears from the processing target image. Alternatively, the region-of-interest detection means 32 may detect a portion where there is a motion between frame images as a region of interest. The resolution (image size) of the region of interest image may be the same as the resolution of the processing target image.

  The image reducing unit 33 generates a reduced image obtained by reducing the image size of the processing target image. In other words, the image reduction means 33 generates an image in which the resolution of the processing target image is reduced to a predetermined resolution. The image reducing unit 33 generates a reduced image by thinning out pixels from the processing target image at a predetermined ratio, for example. The image reduction method is not particularly limited. The image reduction unit 33 reduces the resolution of the processing target image so that the resolution of the reduced image is lower than the resolution of the region-of-interest image.

  The multiplexing unit 34 generates a reduced image reduced by the image reduction unit 33, a region of interest image generated by the region of interest detection unit 32, and a multiplexed image multiplexed on the image space. As will be described later, in the present embodiment, the region-of-interest image is multiplexed into the multiplexed image in the format of the difference image generated by the difference image generation unit 38 instead of the region-of-interest image itself. The multiplexing means 34 has the number of pixels in the horizontal direction of the image equal to the number of pixels in the horizontal direction of the difference image, and the number of pixels in the vertical direction is the number of pixels in the vertical direction of the reduced image and the number of pixels in the vertical direction of the region of interest image. An image equal to the sum can be used as a multiplexed image. The multiplexing unit 34 first arranges the reduced image above the image of the multiplexed image.

  The compression unit 35 compresses the multiplexed image generated by the multiplexing unit 34 and generates compressed image data. The image compression format is not particularly limited. The compression means 35 is, for example, H.264. H.264 performs image compression. The compression unit 35 starts compression from the upper side of the multiplexed image, and temporarily stops the compression when the compression of the reduced image portion is completed. The partial image expansion unit 36 expands the reduced image portion in the compressed multiplexed image based on the compressed image data generated by the compression unit 35. The partial image decompressing unit 36 receives provisional compressed image data at the stage where the reduced image is compressed by the compressing unit 35 when the compressing unit 35 compresses the reduced image part, and the partial image decompressing unit 36 reduces based on the provisional compressed image data. Decompress the image part.

  The enlargement unit 37 enlarges the reduced image portion expanded by the partial image expansion unit 36 to the image size of the processing target image. That is, the enlargement process in the enlargement unit 37 is the reverse of the reduction process in the image reduction unit 33. The difference image generation unit 38 generates a difference image between the reduced image portion enlarged by the enlargement unit 37 and the region of interest image generated by the region of interest detection unit 32. At that time, the difference image generation unit 38 receives the region-of-interest information from the region-of-interest detection unit 32, and generates a difference image for the position corresponding to the region of interest in the processing target image. A portion other than the region of interest in the difference image may be fixed to a predetermined pixel value, for example, 0 (black).

  When the difference image is generated, the multiplexing unit 34 arranges the difference image below the multiplexed image, and multiplexes the reduced image and the difference image into one multiplexed image. When the difference image is arranged in the multiplexed image, the compression unit 35 resumes the compression of the multiplexed image. The image compression unit 35 finally generates compressed image data obtained by compressing the entire multiplexed image in which the reduced image and the difference image are multiplexed on the image space. The output unit 39 outputs the compressed image data to a receiving device via, for example, a communication network. Alternatively, the output means 39 may output the compressed image data to a storage device such as a hard disk drive.

  FIG. 8 shows an operation procedure. The image input unit 31 inputs a processing target image (step S301). The image reducing unit 33 generates a reduced image obtained by reducing the resolution of the processing target image (step S302). For example, the image reduction unit 33 generates a reduced image in which the vertical and horizontal image sizes of the processing target image are each halved and the vertical and horizontal resolutions are reduced to half. The image reducing unit 33 outputs the generated reduced image to the multiplexing unit 34.

  The region of interest detection means 32 detects the region of interest from the processing target image (step S303). The region-of-interest detection means 32 extracts, for example, a region of interest detected from the processing target image, and generates an image in which pixel values other than the extracted portion are fixed to a predetermined value, for example, 0 (black), as the region-of-interest image. The region-of-interest detection unit 32 outputs the generated region-of-interest image and the region-of-interest information indicating the position of the detected region of interest in the processing target image to the difference image generation unit 38.

  The multiplexing unit 34 arranges the reduced image above the image of the multiplexed image for multiplexing the reduced image and the region-of-interest image (difference image) on the image space (step S304). At this stage, the difference image is not yet multiplexed on the multiplexed image, and the multiplexing unit 34 only secures an area for arranging the difference image in the multiplexed image. The compression unit 35 starts to compress the multiplexed image from the upper part of the image (step S305).

  The compression means 35 temporarily stops the compression when the reduced image portion is compressed (step S306). The partial image decompressing unit 36 receives provisional compressed image data at the stage where the reduced image portion is compressed from the compressing unit 35, and decompresses the reduced image portion based on the compressed image data (step S307). The enlarging means 37 enlarges the reduced reduced image part to the size of the processing target image (step S308), and outputs the enlarged reduced image part to the difference image generating means 38. The difference image generation means 38 generates a difference image between the enlarged reduced image portion and the region of interest image at a position corresponding to the region of interest in the processing target image (step S309).

  The difference image generation unit 38 outputs the generated difference image to the multiplexing unit 34. The multiplexing unit 34 adds the difference image to the multiplexed image (step S310). In step S310, the multiplexing unit 34 arranges the difference image below the multiplexed image for which the area has been secured in step S304. The compression unit 35 resumes the compression of the multiplexed image that has been paused (step S311). The output means 39 outputs compressed image data obtained by compressing the entire multiplexed image to a receiving side image decompression device, storage device, or the like (step S312).

  FIG. 9 shows a specific example of an image generated by each unit of the image compression device 30. The input processing target image 301 is given to the region of interest detection means 32 and the image reduction means 33. The image reduction means 33 reduces the resolution of the processing target image 301 and generates a reduced image 302. The processing target image 301 and the reduced image 302 are images representing the same content. However, the image size of the reduced image 302 is smaller than the image size of the processing target image 301.

  The region-of-interest detection means 32 detects, for example, a region constituting a person from the processing target image 301 as a region of interest, and generates a region-of-interest image 307. The region-of-interest detection means 32, for example, generates an image in which the pixel value of the part constituting the detected person is the same as the pixel value of the processing target image 301 and the pixel value of the part other than the person is fixed to 0. It generates as 307. In addition, the region-of-interest detection unit 32 generates region-of-interest information 308 indicating the position of the region of interest in the processing target image.

  The multiplexing unit 34 generates a multiplexed image 303 in which the reduced image 302 is arranged at the upper part of the image. The lower part of the multiplexed image 303 is in a state where the area is secured, and the image is not yet arranged at this stage. The compression unit 35 starts compression from the upper side of the multiplexed image 303 and generates provisional compressed image data 304 in which the reduced image portion is compressed. The partial image decompressing means 36 decompresses the provisional compressed image data 304 and generates the restored reduced image 305. The content of the restored reduced image 305 is the content of the reduced image 302 reduced by the image reducing means 33. Is the same. However, there is a portion where the image quality is not exactly the same and the image quality is degraded by the amount of compression.

  The enlargement unit 37 generates an enlarged image 306 obtained by enlarging the restored reduced image 305 to the image size of the processing target image 301. The difference image generation means 38 uses the region-of-interest information 308 to cut out a portion constituting a person from the region-of-interest image 307, cuts out the same pixel position as the portion constituting the cut-out person from the enlarged image 306, and determines the difference between the two An image 309 is generated. The multiplexing unit 34 generates a multiplexed image 310 in which the difference image 309 is added to the lower part of the multiplexed image 303. The compression unit 35 restarts compression of the multiplexed image 310 from the added difference image portion, and generates compressed image data 311. The compressed image data 311 is output via the output unit 39.

  Next, an image decompression apparatus that decompresses an image compressed by the image compression apparatus 30 will be described. FIG. 10 shows an image expansion device corresponding to the image compression device 30 of the present embodiment. The image expansion device 40 includes data input means 41, expansion means 42, image separation means 43, image enlargement means 44, image composition means 45, and output means 46. The function of each unit of the image expansion device 40 can be realized by, for example, a computer executing processing according to a predetermined program.

  The data input means 41 inputs the compressed image data output from the output means 39 of the image compression apparatus 30 shown in FIG. That is, the data input means 41 multiplexes a reduced image obtained by reducing the processing target image, and a difference image between the region of interest image and an image obtained by enlarging the compressed reduced image portion to the size of the processing target image. The compressed image data obtained by compressing the multiplexed image is input. The decompressing means 42 decompresses the compressed image data and generates a multiplexed image. The decompression unit 42 performs decompression by an expansion method corresponding to the compression method in the compression unit 35 of the image compression device 30.

  The image separation unit 43 separates the reduced image and the difference image from the multiplexed image generated by the decompression unit 42. The image separation unit 43 outputs the separated reduced image to the image enlargement unit 44 and outputs the difference image to the image composition unit 45. The image enlarging means 44 enlarges the separated reduced image to the size of the processing target image. Since the image size of the difference image and the image size of the processing target image are the same size, the image size of the enlarged reduced image is the same as the image size of the difference image. The image enlargement process in the image enlargement unit 44 is the reverse of the image reduction process in the image reduction unit 33 of the image compression device 30.

  The image synthesizing unit 45 generates a synthesized image obtained by synthesizing the difference image and the reduced image enlarged by the image enlarging unit 44. At that time, the image composition unit 45 generates a composite image by adding the enlarged reduced image and the difference image using the region-of-interest information. The region of interest is restored by adding the enlarged reduced image to the difference image. The output means 46 outputs the composite image generated by the image composition means 45 to a display device for performing image display.

  FIG. 11 shows an operation procedure for image decompression. The data input means 41 inputs compressed image data (step S41). The data input means 41 inputs the compressed image data output from the image compression device 30 (FIG. 7) via, for example, a communication network. Alternatively, the data input unit 41 may read the compressed image data from the storage device.

  The decompressing means 42 decompresses the compressed image data and restores the multiplexed image compressed by the image compressing device 30 (step S42). The image separation unit 43 separates the restored multiplexed image into a reduced image and a difference image (step S43). The image enlarging means 44 enlarges the reduced image to the image size of the processing target image (step S44). Super-resolution technology can be used to enlarge the image.

  The image synthesizing unit 45 synthesizes the enlarged reduced image and the difference image (step S45). In step S45, the image composition unit 45 performs image composition by adding the difference image to the enlarged reduced image. The output unit 46 outputs the composite image synthesized by the image synthesis unit 45 to a display device or the like (step S46).

  FIG. 12 shows a specific example of an image generated by each unit of the image expansion device. The compressed image data 401 is, for example, compressed image data obtained by compressing the processing target image 301 illustrated in FIG. 9 by the image compression apparatus 30. The decompressing unit 42 restores the multiplexed image 402 from the compressed image data 401. The contents of the multiplexed image 402 are the same as those of the multiplexed image 310 in FIG. However, there is a portion where the image quality is not exactly the same and the image quality is degraded by the amount of compression.

  The image separation unit 43 separates the reduced image 404 and the difference image 403 from the multiplexed image 402. The separated reduced image 404 is the same image as the reduced image 305 obtained by expanding the temporary compressed image data 304 (FIG. 9) in the image compression apparatus 30. The difference image 403 is substantially the same as the difference image 309 in the image compression apparatus 30. The image enlarging means 44 enlarges the reduced image 404 and generates an enlarged reduced image 405. By enlarging the image, the image size of the enlarged reduced image 405 and the image size of the difference image 403 become the same size.

  The image synthesizing unit 45 adds the difference image 403 to the enlarged reduced image 405 to generate a synthesized image 406. In the image compression device 30, since the difference image 309 is generated by taking the difference between the enlarged image 306 and the region of interest image 307, the region of interest is added by adding the enlarged reduced image 405 and the difference image 403. The part constituting the person included in the image 307 can be reproduced. This synthesized image 406 is the same image as the synthesized image 207 generated by the image pressure decompression apparatus of the first embodiment shown in FIG. The image expansion device 40 outputs a composite image 406.

  In this embodiment, instead of the region of interest image, the difference image is multiplexed into a multiplexed image. More specifically, compression is performed with a reduced image placed on a multiplexed image, the obtained temporary compressed image data is decompressed to restore the reduced image, and the restored reduced image is restored to the original image size. And the difference between the enlarged image and the region-of-interest image is obtained for the region of interest. By taking the difference, a difference image obtained by extracting the harmonic component of the region-of-interest image is obtained. The obtained difference image is arranged at the lower part of the multiplexed image, and the reduced image and the difference image are multiplexed into one multiplexed image. By expanding the reduced image portion of the multiplexed image, enlarging the expanded image and adding it to the difference image, it is possible to obtain a region-of-interest image before taking the difference. In the present embodiment, since the original region-of-interest image can be reproduced without using the region-of-interest information on the data decompression side, it is not necessary to add the region-of-interest information to the compressed image data on the compression side. In particular, when super-resolution is used for enlarging a reduced image, the amount of information of the difference image can be reduced, and an effect that high compression is possible while maintaining the image quality is obtained. Other effects are the same as those of the first embodiment.

  Note that the arrangement of the reduced image and the region-of-interest image (difference image) in the multiplexed image is not limited to those described in the above embodiments, and various multiplexing methods can be considered. For example, another example of multiplexing a reduced image and a region-of-interest image is shown in FIG. Assume that the size of the reduced image is half the size of the region-of-interest image. For example, when an interlaced image is input to the image input means 11 (FIG. 1), as shown in FIG. 13, the even field and the odd field are arranged in the horizontal direction at the top of the image, and the even field is at the bottom of the image. And the odd-numbered field-of-interest images may be arranged in the vertical direction. Alternatively, when an image is input progressively, the image may be separated into odd and even lines, and multiplexing as shown in FIG. 13 may be performed. In this case, the size of the multiplexed image is equal to the horizontal size of the region-of-interest image in the horizontal direction, and the vertical direction is half the vertical size of the reduced image plus the vertical size of the region-of-interest image. Will be equal. When not interlaced, as shown in FIG. 3 as a multiplexed image 104, a blank portion where no image is arranged is formed at the top of the image. By dividing the reduced image into even-numbered fields and odd-numbered fields and arranging them side by side in the multiplexed image, unnecessary blank portions can be reduced.

  In each of the above embodiments, the image compression device and the image expansion device are described as separate devices. However, an image compression / expansion device (system) may be configured by combining the image compression device and the image expansion device. In the image compression / decompression system, the image compression side and the decompression side may be arranged at different locations. For example, the image compression apparatus side may be disposed in a facility to be monitored together with the photographing apparatus, the image expansion apparatus side may be disposed in a monitoring center or the like, and the two may be connected using a communication line or the like. In that case, for example, it is possible to construct a remote monitoring system capable of displaying the portion constituting the person with high image quality while increasing the compression rate of the portion corresponding to the background portion to reduce the data transmission amount.

  In the first embodiment, the region of interest detected by the region of interest detection unit 12 is not limited to one, and the region of interest detection unit 12 may detect a plurality of regions of interest. In that case, the multiplexing unit 14 may multiplex a plurality of region-of-interest images and reduced images into a single multiplexed image. In the second embodiment, the region of interest detection means 32 may detect a plurality of regions of interest. In that case, the difference image generation means 38 may take a difference between each of the detected plurality of region-of-interest images and the reduced image, and generate a plurality of difference images corresponding to each of the plurality of region-of-interest images. The multiplexing unit 34 may multiplex a plurality of difference images and reduced images into one multiplexed image.

  Although the present invention has been described based on the preferred embodiment, the image compression apparatus, decompression apparatus, method, and program of the present invention are not limited to the above embodiment, and the configuration of the above embodiment. To which various modifications and changes are made within the scope of the present invention.

10, 30: Image compression device 11, 31: Image input means 12, 32: Region of interest detection means 13, 33: Image reduction means 14, 34: Multiplexing means 15, 35: Compression means 16: Region of interest information addition means 17 39: output means 36: partial image decompression means 37: enlargement means 38: difference image generation means 20, 40: image decompression device 21, 41: data input means 22: region of interest information separation means 23, 42: decompression means 24, 43: Image separation means 25, 44: Image enlargement means 26, 45: Image composition means 27, 46: Output means 101, 301: Process target images 102, 302, 305: Reduced image 103, 307: Region-of-interest images 104, 303 310: Multiplexed image 105, 308: Region of interest information 106, 311: Compressed image data 304: Temporary compressed image data 305: Reduced image 306 Enlarged image (enlarged reduced image)
309: Difference image 201, 401: Compressed image data 202, 402: Multiplexed image 203: Region of interest image 204, 404: Reduced image 205, 405: Enlarged reduced image 206: Region of interest information 207, 406: Composite image 403 : Difference image

Claims (18)

Image reduction means for generating a reduced image obtained by reducing the image size of the input processing target image;
A region of interest detecting means for detecting a region of interest from the processing target image and generating a region of interest image obtained by extracting the detected region of interest from the processing target image;
Multiplexing means for generating a multiplexed image obtained by multiplexing the reduced image and the region-of-interest image on an image space;
An image compression apparatus comprising: compression means for generating compressed image data obtained by compressing the multiplexed image generated by the multiplexing means.   The image compression apparatus according to claim 1, wherein the image multiplexing unit multiplexes the reduced image and the region-of-interest image in different regions of the multiplexed image.   The multiplexing means arranges the reduced image above the multiplexed image and arranges the region-of-interest image below the multiplexed image to multiplex the images. The image compression apparatus according to claim 1 or 2. Partial image expansion means for expanding the reduced image portion in the multiplexed image compressed by the compression means based on the compressed image data;
Enlarging means for enlarging the reduced image portion expanded by the partial image expanding means to the image size of the processing target image;
A difference image generating means for generating a difference image between the reduced image portion enlarged by the enlargement means and the region of interest image at a position corresponding to the region of interest in the processing target image;
The compression means starts compression from the upper part of the multiplexed image, and temporarily stops compression at the stage where compression of the reduced image portion is finished,
The partial image decompression unit receives provisional compressed image data obtained by compressing the reduced image from the compression unit when the compression unit compresses the reduced image part, and the received provisional compressed image data. Decompressing the reduced image portion based on
The multiplexing means, instead of the region-of-interest image, arranges the difference image below the multiplexed image, thereby multiplexing the reduced image and the difference image on an image space,
The image compression apparatus according to claim 3, wherein the compression unit restarts compression of the multiplexed image after the difference image is arranged at a lower part of the multiplexed image.   The region-of-interest information adding means for adding region-of-interest information regarding the position of the detected region of interest in the processing target image to the compressed image data is further provided. Image compression device. The compressed image data obtained by compressing a multiplexed image in which a reduced image obtained by reducing a processing target image and a region-of-interest image obtained by extracting a region-of-interest portion from the processing target image in an image space is expanded, and the multiplexing is performed. Decompression means for generating a digitized image;
Image separation means for separating the reduced image and the region-of-interest image from the multiplexed image generated by the decompression means;
Image enlarging means for enlarging the separated reduced image to the size of the processing target image;
An image expansion apparatus comprising: an image composition unit that generates a composite image obtained by combining the reduced image enlarged by the enlargement unit and the region-of-interest image. The compressed image data further includes region-of-interest information separating means for separating the region-of-interest information from the compressed image data, to which region-of-interest information relating to the position of the region of interest in the processing target image is added.
The said image synthetic | combination means produces | generates the said synthetic | combination image by superimposing the said region of interest image on the said enlarged reduction image using the said region of interest information. Image decompression device. In the multiplexed image, instead of the region-of-interest image, a difference image between the image of the region-of-interest image and the image obtained by enlarging the compressed reduced image portion to the size of the processing target image is multiplexed,
The image separating means separates the reduced image and the difference image from the multiplexed image instead of the region of interest image,
The image expansion device according to claim 6, wherein the image synthesizing unit synthesizes the enlarged reduced image and the difference image instead of the region-of-interest image.   9. The image decompression apparatus according to claim 8, wherein the image composition unit generates the composite image by adding the difference image to the enlarged reduced image. Image reduction means for generating a reduced image obtained by reducing the image size of the input processing target image;
A region of interest detecting means for detecting a region of interest from the processing target image and generating a region of interest image obtained by extracting the detected region of interest from the processing target image;
Image combining means for generating a multiplexed image obtained by multiplexing the reduced image and the region-of-interest image on an image space;
Compression means for generating compressed image data obtained by compressing the multiplexed image generated by the image composition means;
Decompression means for decompressing the compressed image data and generating the multiplexed image;
Image separation means for separating the reduced image and the region-of-interest image from the multiplexed image generated by the decompression means;
Image enlarging means for enlarging the separated reduced image to the size of the processing target image;
An image compression / decompression apparatus comprising: an image synthesis unit that generates a synthesized image obtained by synthesizing the reduced image enlarged by the enlargement unit and the region-of-interest image. Generating a reduced image obtained by reducing the image size of the input processing target image;
Detecting a region of interest from the processing target image, and generating a region of interest image obtained by extracting the detected region of interest from the processing target image;
Generating a multiplexed image obtained by multiplexing the reduced image and the region-of-interest image on an image space;
An image compression method comprising: generating compressed image data obtained by compressing the generated multiplexed image. Generating a reduced image obtained by reducing the image size of the input processing target image;
Detecting a region of interest from the processing target image, and generating a region of interest image obtained by extracting the detected region of interest from the processing target image;
Disposing the reduced image above the multiplexed image for multiplexing the reduced image and the region-of-interest image on an image space, and sequentially compressing the multiplexed image from the upper side of the image;
When the reduced image portion of the multiplexed image is compressed, the compression of the multiplexed image is temporarily stopped, and the reduced image portion is expanded based on provisional compressed image data at the stage of compressing the reduced image portion. And steps to
Enlarging the decompressed reduced image portion to the size of the processing target image;
Generating a difference image between the enlarged reduced image portion and the region-of-interest image for a position corresponding to the region-of-interest portion in the processing target image;
Placing the difference image below the multiplexed image, restarting compression of the multiplexed image after the placement, and generating compressed image data obtained by compressing the multiplexed image. Image compression method. The compressed image data obtained by compressing a multiplexed image in which a reduced image obtained by reducing a processing target image and a region-of-interest image obtained by extracting a region-of-interest portion from the processing target image in an image space is expanded, and the multiplexing is performed. Generating a digitized image;
Separating the reduced image and the region-of-interest image from the generated multiplexed image;
Enlarging the separated reduced image to the size of the processing target image;
An image expansion method comprising: generating a composite image obtained by combining the enlarged reduced image and the region-of-interest image. A reduced image obtained by reducing a processing target image, and a multiplexed image obtained by multiplexing a difference image between an image obtained by enlarging a compressed reduced image portion to the size of the processing target image and the region of interest image in an image space. Decompressing compressed compressed image data to generate the multiplexed image; and
Separating the reduced image and the difference image from the generated multiplexed image;
Enlarging the separated reduced image to the size of the processing target image;
An image expansion method comprising: generating a composite image obtained by combining the enlarged reduced image and the difference image. On the computer,
A procedure for generating a reduced image obtained by reducing the image size of the input processing target image;
A step of detecting a region of interest from the processing target image and generating a region of interest image obtained by extracting the detected region of interest from the processing target image;
Generating a multiplexed image obtained by multiplexing the reduced image and the region-of-interest image on an image space;
A program for executing compressed image data obtained by compressing the generated multiplexed image. On the computer,
A procedure for generating a reduced image obtained by reducing the image size of the input processing target image;
A step of detecting a region of interest from the processing target image and generating a region of interest image obtained by extracting the detected region of interest from the processing target image;
Placing the reduced image above the image of the multiplexed image for multiplexing the reduced image and the region-of-interest image on an image space, and sequentially compressing the multiplexed image from the upper side of the image;
When the reduced image portion of the multiplexed image is compressed, the compression of the multiplexed image is temporarily stopped, and the reduced image portion is expanded based on provisional compressed image data at the stage of compressing the reduced image portion. And the steps to
A procedure for enlarging the decompressed reduced image portion to the size of the processing target image;
Generating a difference image between the enlarged reduced image portion and the region-of-interest image for a position corresponding to the region of interest in the processing target image;
A step of arranging the difference image below the multiplexed image, restarting compression of the multiplexed image after the arrangement, and generating compressed image data obtained by compressing the multiplexed image program. On the computer,
The compressed image data obtained by compressing a multiplexed image in which a reduced image obtained by reducing a processing target image and a region-of-interest image obtained by extracting a region-of-interest portion from the processing target image in an image space is expanded, and the multiplexing is performed. To generate a digitized image;
Separating the reduced image and the region-of-interest image from the generated multiplexed image;
A procedure for enlarging the separated reduced image to the size of the processing target image;
A program for executing a procedure for generating a synthesized image obtained by synthesizing the enlarged reduced image and the region-of-interest image. On the computer,
A reduced image obtained by reducing a processing target image, and a multiplexed image obtained by multiplexing a difference image between an image obtained by enlarging a compressed reduced image portion to the size of the processing target image and the region of interest image in an image space. A procedure for decompressing compressed compressed image data and generating the multiplexed image;
Separating the reduced image and the difference image from the generated multiplexed image;
A procedure for enlarging the separated reduced image to the size of the processing target image;
A program for executing a procedure for generating a synthesized image obtained by synthesizing the enlarged reduced image and the difference image.