Image coding device, integrated circuit thereof, and image coding method
To aim to achieve addition of blur to an image based on distance information of a subject and to appropriate determination of a block size that is a unit for coding. Blur is added to the image with use of one of disparity information for each pixel unit and distance information for each pixel unit and arbitrary blur conditions. A block size of each region of the image that are to be divided into blocks for coding is determined based on a blur value of the region. The image is divided into blocks based on the determined block sizes and coded in units of blocks. By increasing a block size with respect to a region included in an image having a high blur value, it is possible to reduce processing amount of reference block searching, thereby achieving speed-up of processing and reduction in processing amount.
1. An image coding device comprising:
an image acquisition unit configured to acquire one or more images;
a disparity acquisition unit configured to acquire, with respect to each of the acquired images, one of disparity information for each pixel unit and distance information for each pixel unit;
a blur value determination unit configured to determine a blur value of the image for each pixel unit based on the acquired one of the disparity information and the distance information;
a blur processing unit configured to perform blur processing on the image with use of the determined blur value;
a block size determination unit configured to determine, with respect to the image on which the blur processing has been performed, a block size of each of regions of the image that are to be divided into blocks for coding, from among a plurality of block sizes based on a blur value of the region; and
a coding unit configured to code the image in units of blocks in accordance with the determined block sizes.
2. The image coding device of claim 1 , wherein
the blur value determination unit determines the blur value based on a blur parameter of the image, in addition to based on the acquired one of the disparity information and the distance information.
3. The image coding device of claim 2 , wherein
the blur parameter includes an optical characteristic value that differs from a characteristic value of an optical system by which the image has been photographed.
4. The image coding device of claim 3 , wherein
the blur parameter includes focus point information of at least one subject included in the image.
5. The image coding device of claim 1 , wherein
with respect to a pixel unit having a blur value higher than a threshold value, the block size determination unit determines a block size other than the smallest block size among the plurality of block sizes.
6. The image coding device of claim 5 , wherein
the coding unit performs one of motion compensated prediction, disparity compensated prediction, and intra prediction on the image, by searching for a block similar to each of the blocks of the image with use of the determined block size for each of the blocks, selecting a block size of the most similar block resulting from the searching, and generating a prediction residual signal of each of the blocks with use of the selected block size.
7. The image coding device of claim 1 , wherein
with respect to a pixel unit having a blur value lower than a threshold value, the block size determination unit determines at least the smallest block size among the plurality of block sizes.
8. The image coding device of claim 6 , wherein
the coding unit performs one of motion compensated prediction, disparity compensated prediction, and intra prediction on the image, by searching for a block similar to each of the blocks of the image with use of the determined block size for each of the blocks, selecting a block size of the most similar block resulting from the searching, and generating a prediction residual signal of each of the blocks with use of the selected block size.
9. The image coding device of claim 1 , wherein
the image acquisition unit acquires a left-view image and a right-view image for use in stereoscopic image display, and
the disparity acquisition unit includes a disparity detection subunit configured to detect disparity between a region of the left-view image and a region of the right-view image in correspondence with each other.
10. The image coding device of claim 1 , wherein
the image acquisition unit includes a stereoscopic image generation subunit configured to generate a stereoscopic image composed of a left-view image and a right-view image based on an acquired image, one of disparity information and distance information with respect to the acquired image.
11. An integrated circuit comprising:
an image acquisition unit configured to acquire one or more images;
a disparity acquisition unit configured to acquire, with respect to each of the acquired images, one of disparity information for each pixel unit and distance information for each pixel unit;
a blur value determination unit configured to determine a blur value of the image for each pixel unit based on the acquired one of the disparity information and the distance information;
a blur processing unit configured to perform blur processing on the image with use of the determined blur value;
a block size determination unit configured to determine, with respect to the image on which the blur processing has been performed, a block size of each of regions of the image that are to be divided into blocks for coding, from among a plurality of block sizes based on a blur value of the region; and
a coding unit configured to code the image in units of blocks in accordance with the determined block sizes.
12. An image coding method comprising:
an image acquisition step of acquiring one or more images;
a disparity acquisition step of acquiring, with respect to each of the acquired images, one of disparity information for each pixel unit and distance information for each pixel unit;
a blur value determination step of determining a blur value of the image for each pixel unit based on the acquired one of the disparity information and the distance information;
a blur processing step of performing blur processing on the image with use of the determined blur value;
a block size determination step of determining, with respect to the image on which the blur processing has been performed, a block size of each of regions of the image that are to be divided into blocks for coding, from among a plurality of block sizes based on a blur value of the region; and
a coding step of coding the image in units of blocks in accordance with the determined block sizes.
13. An image coding system that includes a camera for photographing an image, an image coding device for coding the photographed image to generate compressed image data, and a non-transitory recording medium for recording therein the compressed image data,
the image coding device comprising:
an image acquisition unit configured to acquire one or more images;
a disparity acquisition unit configured to acquire, with respect to each of the acquired images, one of disparity information for each pixel unit and distance information for each pixel unit;
a blur value determination unit configured to determine a blur value of the image for each pixel unit based on the acquired one of the disparity information and the distance information;
a blur processing unit configured to perform blur processing on the image with use of the determined blur value;
a block size determination unit configured to determine, with respect to the image on which the blur processing has been performed, a block size of each of regions of the image that are to be divided into blocks for coding, from among a plurality of block sizes based on a blur value of the region; and
a coding unit configured to code the image in units of blocks in accordance with the determined block sizes.