Method of transform data compression using save-maps
First Claim
1. A method for compressing the data required to represent an original image by using a predefined set of save-maps, with each save-map being identified by an index and each save-map identifying a subset of transform coefficients, comprising the steps of:
- spatially partitioning said image into a plurality of blocks;
generating, for each block of at least a subset of said plurality of blocks, a set of transform coefficients representative of the data spatially located in that block, with each of said transform coefficients having a magnitude component and a frequency component;
partitioning each block of transform coefficients into a plurality of zones, the dimensions of each said zone being a function of the different visual components of the image;
generating an index independently for each said block as a function of the energy level in more than one zone of the block;
selecting one of said save-maps as a function of said index; and
employing said index and the magnitude components of the subset of transform coefficients for each said block identified by said selected save-map for that block to represent that portion of said image spatially contained in that block.
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Abstract
A method for compressing the data required to represent an image using a set of save-maps, with each save-map being identified by an index and each save-map identifying a subset of transform coefficients. The method begins by spatially partitioning the image into a plurality of blocks, includes the generation of transform coefficients representative of the data spatially located in each block; the generation of an index for each block as a function of the transform coefficients for that block; and selecting one of the save-maps as a function of the index. By employing the index and the value of the magnitude components of the subset of transform coefficients identified by the selected save-map for each block, compressed data may be obtained representative of that portion of the image spatially contained in each of the corresponding blocks. Thus, each save-map permits retrieving the original image in accordance with the save-map and data representative of the magnitude components of the subsets of transform coefficients identified by the save-maps.
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Citations
8 Claims
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1. A method for compressing the data required to represent an original image by using a predefined set of save-maps, with each save-map being identified by an index and each save-map identifying a subset of transform coefficients, comprising the steps of:
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spatially partitioning said image into a plurality of blocks; generating, for each block of at least a subset of said plurality of blocks, a set of transform coefficients representative of the data spatially located in that block, with each of said transform coefficients having a magnitude component and a frequency component; partitioning each block of transform coefficients into a plurality of zones, the dimensions of each said zone being a function of the different visual components of the image; generating an index independently for each said block as a function of the energy level in more than one zone of the block; selecting one of said save-maps as a function of said index; and employing said index and the magnitude components of the subset of transform coefficients for each said block identified by said selected save-map for that block to represent that portion of said image spatially contained in that block. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for compressing the data required to represent an original image by using a set of save-maps, with each save-map being identified by an index and each save-map identifying a subset of transform coefficients, comprising the steps of:
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spatially partitioning said image into a plurality of blocks; generating, for each block of at least a subset of said plurality of blocks, a set of transform coefficients representative of the data spatially located in that block, with each of said transform coefficients having a magnitude component and a frequency component; generating an index for each said block as a function of said transform coefficients for that block, comprising the steps of; organizing the set of transform coefficients for that block into a matrix based on said frequency components of said transform coefficients; partitioning at least a portion of said matrix into a plurality of zones; summing the absolute values of the magnitude components of the transform coefficients in each zone to obtain a plurality of zone sums; summing the absolute values of the magnitude components of all the transform coefficients to obtain a total sum; dividing each zone sum by said total sum to obtain a normalized zonal activity level for each zone; and comparing said total sum and said normalized zonal activity level with corresponding predefined empirical values to generate a code which constitutes the index for each said block; selecting one of said save-maps as a function of said index; and employing said index and the magnitude components of the subset of transform coefficients for each said block identified by said selected save-map for that block to represent that portion of said image spatially contained in that block. - View Dependent Claims (8)
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Specification