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Method and apparatus for compression and decompression of video data streams

  • US 5,828,848 A
  • Filed: 10/31/1996
  • Issued: 10/27/1998
  • Est. Priority Date: 10/31/1996
  • Status: Expired due to Term
First Claim
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1. A method of performing data compression with respect to a frame of image data, said image data being representative of pixels arrayed in an image plane, the method comprising the steps of:

  • dividing said image data into a plurality of data blocks, each of said data blocks representing a respective rectangular part of said image plane;

    comparing each of said data blocks with a corresponding data block of a preceding frame of image data to generate a similarity metric indicative of a degree of similarity between said each data block and the corresponding data block of the preceding frame;

    comparing said similarity metric with a predetermined threshold value;

    on the basis of said comparison of said similarity metric with said predetermined threshold value, selecting one of a first mode for generating encoding values for said each data block and a second mode for generating encoding values for said each data block;

    generating encoding values for said each data block in accordance with the selected one of said first mode and said second mode; and

    applying a transformation to said encoding values of said each data block to form a respective block of coefficient values therefrom.

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