Image data compression employing optimal subregion compression
First Claim
1. A method for compressing image data from an uncompressed image data stream, the method comprising the steps of:
- (a) receiving the uncompressed image data stream;
(b) analyzing the uncompressed image data stream by contiguous subregions to identify from a plurality of compression algorithms a compression algorithm that permits optimal lossless compression of each subregion;
(c) selecting an optimal data compression algorithm for each subregion based upon the analysis performed in step (b); and
(d) compressing the image data stream by subregion based upon the selected algorithms.
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Abstract
An image data compression technique includes division of an image data stream into a plurality of subregions and optimal compression of each subregion. The subregions may represent adjacent pixels in a reconstructed image, and may all be of the same length. The length of the subregions may be set to a default, and may be altered based upon image characteristics. The subregions are analyzed for selection of an optimal compression algorithm for each subregion from a set of candidate algorithms. Criteria for selection of the optimal algorithms may include the relative entropy levels of data within the subregions, and the length of compressed data code resulting from application of each of the candidate algorithms.
69 Citations
30 Claims
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1. A method for compressing image data from an uncompressed image data stream, the method comprising the steps of:
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(a) receiving the uncompressed image data stream;
(b) analyzing the uncompressed image data stream by contiguous subregions to identify from a plurality of compression algorithms a compression algorithm that permits optimal lossless compression of each subregion;
(c) selecting an optimal data compression algorithm for each subregion based upon the analysis performed in step (b); and
(d) compressing the image data stream by subregion based upon the selected algorithms. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for compressing an image data stream including a descriptive header portion and an image data portion appended to the descriptive header portion, the method comprising the steps of:
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(a) selecting an analysis algorithm from a plurality of candidate analysis algorithms for computation of variations in values of data of individual, contiguous subregions of the image data portion representative of neighboring discrete picture elements of an image represented by the image data portion;
(b) selecting an optimal lossless data compression algorithm for each subregion from a plurality of candidate compression algorithms based upon the variations computed in step (a); and
(c) compressing at least the image data portion in accordance with the selected compression algorithm for each subregion. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for compressing an image data stream, the method comprising the steps of:
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(a) selecting desired lengths of subregions of the image data, each subregion comprising a plurality of individual picture elements of an image encoded by the image data stream;
(b) analyzing each subregion to identify lengths of compressed data streams resulting from lossless compression of the respective subregion in accordance with each of a plurality of candidate compression algorithms;
(c) selecting a desired lossless compression algorithm for each subregion from the plurality of candidate compression algorithms based upon the analysis performed in step (b); and
(d) compressing the image data stream by subregion in accordance with the desired compression algorithms. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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27. A computer program for compressing image data, the computer program comprising:
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a machine readable medium for supporting machine readable code; and
configuration code stored on the machine readable medium for subdividing image data into subregions, selecting an optimal lossless compression algorithm for each subregion from a plurality of candidate compression algorithms based upon analysis of the subregion, and losslessly compressing each subregion in accordance with the selected compression algorithms. - View Dependent Claims (28, 29, 30)
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Specification