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Hierarchical encoding and decoding apparatus for a digital image signal

  • US 5,663,764 A
  • Filed: 07/19/1995
  • Issued: 09/02/1997
  • Est. Priority Date: 09/30/1993
  • Status: Expired due to Term
First Claim
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1. A hierarchical encoding apparatus for encoding a first digital image signal representing pixels and having a first resolution, comprising:

  • means for forming a second digital image signal from the first digital image signal, the second digital image signal having a second resolution lower than the first resolution;

    predicting means for producing predicted values of the first digital image signal from the second digital image signal;

    means for subtracting a predicted value of the first digital image signal from the pixel value of the first digital image signal to produce a differential value; and

    means for transmitting the second digital image signal and a differential signal representing the differential values;

    wherein the predicting means comprises;

    class categorizing means for determining a class corresponding to a selected pixel of the second digital image signal;

    the class categorizing means being operative to produce a plurality of predicted pixel values of the selected pixel, each of the predicted pixel values corresponding to a respective one of a plurality of predetermined classes;

    the class categorizing means being further operative to select a class corresponding to the selected pixel from the plurality of predetermined classes based on a respective one of the plurality of predicted pixel values which is closest to a value of the selected pixel; and

    predicted value generating means for generating a predicted value of the first digital image signal based on the selected class.

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