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Method of transform data compression using save-maps

  • US 5,038,390 A
  • Filed: 06/05/1990
  • Issued: 08/06/1991
  • Est. Priority Date: 06/05/1990
  • Status: Expired due to Term
First Claim
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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:

  • 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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