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Adaptive zonal coder

  • US 5,063,608 A
  • Filed: 11/03/1989
  • Issued: 11/05/1991
  • Est. Priority Date: 11/03/1989
  • Status: Expired due to Term
First Claim
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1. A method for image data compression comprising the steps of:

  • transforming a two-dimensional block of image data in a spatial domain to resulting data in a frequency domain represented as a two-dimensional array of activity coefficients;

    serializing said entire two-dimensional array of coefficients, yielding a one-dimensional array of coefficients with a leading coefficient and an original trailing coefficient;

    quantizing said one-dimensional array of coefficients;

    selecting a portion of said one-dimensional array of coefficients beginning with said leading coefficient and ending with a new trailing coefficient that is closer to the leading coefficient than said original trailing coefficient, wherein said portion is selected by a process comprising the steps of;

    obtaining a measure of total activity of said one-dimensional array of coefficients,determining in real time a measure of activity of successive sub-portions of said one-dimensional array, and adding said measure of activity to a running total,performing a comparison in real time of said running total to a setable level based on said measure of total activity, anddesignating a new trailing coefficient according to said comparison;

    appending an end-of-block symbol after said new trailing coefficient; and

    encoding only said portion with an entropy coder.

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