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Method of orthogonal transform coding/decoding

  • US 5,079,547 A
  • Filed: 02/27/1991
  • Issued: 01/07/1992
  • Est. Priority Date: 02/28/1990
  • Status: Expired due to Fees
First Claim
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1. A method of orthogonal transform coding to quantize transformed coefficients which are divided into a plurality of bands to which respective different numbers of coefficients are allotted, comprising the steps of:

  • arranging a plurality of quantization threshold level-tables designed on the basis of a probability density function of coefficient value on the assumption of a pre set number of coefficients, the quantization threshold level-tables corresponding to pre-set plural numbers of quantization bits respectively,selecting a table among the quantization threshold level-tables in response to a number of bits which the quantization of coefficients on a band is to be performed, andcompensating the quantization levels in the selected table with the square root of a ratio of the number of coefficients on tee band to the pre-set number of coefficients,thus to compare the coefficient values and the compensated threshold levels with each other to quantize the coefficient values.

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