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Method and apparatus for low frequency removal in vector quantization

  • US 5,235,418 A
  • Filed: 11/19/1991
  • Issued: 08/10/1993
  • Est. Priority Date: 11/19/1991
  • Status: Expired due to Term
First Claim
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1. In a vector quantization data compression system employing a first vector quantization codebook for compressing an image frame for transmission to a plurality of reception sites, said codebook having a plurality of codevectors, each codevector being representative of a possible residual vector, there being an identification (ID) code associated with each codevector, a method comprising the steps of:

  • a) receiving an image frame to be transmitted, organizing the image frame into a plurality of blocks of data, and converting each block to a multi-dimensional input vector;

    b) determining a mean value of each input vector and transmitting at least an indication of each mean value to at least one reception site;

    c) performing the following additional steps for each input vector;

    i) processing at least a portion of said means values to produce a low-frequency component vector representative of a low-pass version of the input vector;

    ii) subtracting the low-frequency component vector produced in step (c)(i) from the input vector to obtain a low-frequency removed vector;

    iii) determining a mean value of the low-frequency removed vector and subtracting the mean value of the low-frequency removed vector therefrom to obtain a residual vector;

    iv) selecting from the first codebook the codevector that most closely resembles the residual vector; and

    v) transmitting at least an indication of the ID code associated with the selected codevector to at least one reception site, said indication representing vector quantized data.

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