Method and apparatus for controlling image quality and compression ratios
View Patent ↗This invention relates to a method and apparatus for controlling image quality and compression ratios in image segmentation. More particularly, the invention is directed to an image segmenting system and method that analyzes and classifies pixel blocks of an image to determine the manner in which the image block should be compressed, e.g. with a lossy or a lossless technique. This approach, which assumes no apriori knowledge of the any specific region of the image, results in effective use of the various known compression techniques and provides improved overall compression ratios and image quality.
1. An apparatus for controlling image quality and compression ratios in compressing an image comprised of a plurality of pixel blocks, the apparatus comprising:
a block analyzer operative to sequentially analyze the blocks to determine values of at least two metrics therefor; and,
a block classifier, including block mapping assignments in accord with a metric partitioning strategy based on the at least two metrics, the block classifier being operative to determine which of a plurality of compression schemes will be selected to compress each of the blocks based on the determined metric values and the block mapping assignments.
2. The apparatus as set forth in claim 1 wherein at least one of the plurality of compression schemes is a lossy compression scheme.
3. The apparatus as set forth in claim 2 wherein the lossy compression scheme comprises JPEG compression.
4. The apparatus as set forth in claim 3 wherein the JPEG compression comprises at least one of JPEG Aggressive and JPEG Gentle.
5. The apparatus as set forth in claim 1 wherein at least one of the plurality of compression schemes comprises a lossless compression scheme.
6. The apparatus as set forth in claim 5 wherein the lossless compression scheme comprises a Lempel-Ziv compression scheme.
7. The apparatus as set forth in claim 1 further comprising a lossy compression channel and a lossless compression channel, the image blocks being respectively compressed therein.
8. The apparatus as set forth in claim 7 further comprising a system for decompressing compressed data.
9. The apparatus as set forth in claim 1 wherein the block classifier comprises a look-up table.
10. The apparatus as set forth in claim 1 , wherein the block classifier is operative to determine which of the plurality of compression schemes will be selected to compress each block by locating the determined metrics within a metric space defined by ranges of possible values of the at least two metrics regions of the metric space being pre-associated with selected ones of the plurality of compression schemes, the locating thereby mapping the determined metrics to a compression scheme.
11. An apparatus for controlling image quality and compression ratios in compressing an image comprised of a plurality of pixel blocks, the apparatus comprising:
a block analyzer operative to sequentially analyze the blocks to determine at least an activity metric therefor; and,
a block classifier operative to determine which of a plurality of compression schemes will be selected to compress each of the blocks based on the determined metrics.
12. An apparatus for controlling image quality and compression ratios in compressing an image comprised of a plurality of pixel blocks, the apparatus comprising:
a block analyzer operative to sequentially analyze the blocks to determine at least a color count metric therefor; and,
a block classifier operative to determine which of a plurality of compression schemes will be selected to compress each of the blocks based on the determined metrics.
13. An apparatus for controlling image quality and compression ratios in compressing an image comprised of a plurality of pixel blocks, the apparatus comprising:
a block analyzer operative to sequentially analyze the blocks to determine at least an edge energy metric therefor; and,
a block classifier operative to determine which of a plurality of compression schemes will be selected to compress each of the blocks based on the determined metrics.
14. An apparatus for controlling image quality and compression ratios in compressing an image comprised of a plurality of pixel blocks, the apparatus comprising:
a block analyzer operative to sequentially analyze the blocks to determine a plurality of metrics including an edge count metric therefor; and,
a block classifier operative to determine which of a plurality of compression schemes will be selected to compress each of the blocks based on the determined metrics.
15. A method useful on an image comprising pixel blocks, the method comprising:
determining block mapping assignments based on at least two metrics and evaluations of test image quality and performance of compression options;
inputting the image;
sequentially analyzing the blocks of the image to determine values of the at least two metrics therefor;
determining a manner in which each block will be compressed based on the block mapping assignments and the determined values of the at least two metrics; and
compressing each block based on the determining.
16. The method as set forth in claim 15 further comprising decompressing the blocks based on the determining.
17. An apparatus comprising:
means for receiving an image comprised of blocks;
means for sequentially analyzing the blocks to determine at least two metrics therefor;
means for determining a manner in which each block will be compressed based on the at least two metrics; and,
means for compressing each block based on the determining means.
18. The apparatus as set forth in claim 17 further comprising a means for decompressing the blocks based on the determining means.