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Coded data transform method, transcoding method, transcoding system, and data storage media

  • US 6,590,936 B1
  • Filed: 04/13/2000
  • Issued: 07/08/2003
  • Est. Priority Date: 04/13/1999
  • Status: Expired due to Fees
First Claim
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1. A coded data transform method including a decoding process for decoding first coded data which has been obtained by subjected image data, for each coding unit, to a coding process including a first orthogonal transform process and a first quantization process to generate decoded data, and a transcoding process for coding the decoded data, for each coding unit, to generate second coded data, wherein:

  • said decoding process comprises;

    an inverse quantization process for inversely quantizing quantized coefficients obtained from the first coded data by using a first quantization step which has been used in the first quantization process; and

    said transcoding process comprises;

    a second orthogonal transform process for subjecting the decoded data to orthogonal transform to generate frequency-domain data; and

    a second quantization process for deriving a second quantization step on the basis of the second coded data and the first quantization step, and quantizing the frequency-domain data with the second quantization step.

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