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Image encoding apparatus

  • US 5,631,644 A
  • Filed: 12/22/1994
  • Issued: 05/20/1997
  • Est. Priority Date: 12/22/1993
  • Status: Expired due to Fees
First Claim
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1. An image encoding apparatus comprising:

  • quantizing means for quantizing an input image;

    variable-length encoding means for performing variable-length encoding on the quantized result of said quantizing means;

    temporary storage means for temporarily storing encoded data from said variable-length encoding means, the stored encoded data thereafter being transmitted at a fixed data rate;

    encoded data amount control means for calculating a quantization step size of quantizing information to be encoded based upon the encoded result of said variable-length encoding means to control an amount of data encoded by said variable-length encoding means;

    dummy data generating means for generating dummy data, eliminatable when decoding the encoded data;

    switching means for switching an output of said image encoding apparatus between the encoded data from said temporary storage means and the dummy data from said dummy data generating means; and

    control means for monitoring a number of occupied bits of encoded data in said temporary storage means to control switching of said switching means such that the output of the image encoding apparatus is the encoded data from said temporary storage means when the number of occupied bits of encoded data exceeds a predetermined threshold, and such that transmission of encoded data from said temporary storage means is suspended and the output of the image encoding apparatus is the dummy data generated from said dummy data generating means when the number of occupied bits of encoded data is not more than the predetermined threshold, wherein said control means outputs a switching signal to said encoded data amount control means when the number of occupied bits of encoded data is not more than the predetermined threshold, andsaid encoded data amount control means initializes parameters which are used for calculation of the quantization step size when the switching signal is output.

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