×

Image data compressing/coding apparatus

  • US 5,335,016 A
  • Filed: 01/23/1992
  • Issued: 08/02/1994
  • Est. Priority Date: 01/29/1991
  • Status: Expired due to Fees
First Claim
Patent Images

1. An apparatus for dividing image data into blocks with a predetermined size, subjecting the image data of the blocks to an orthoganol transformation to obtain orthogonal transformation coefficients, quantizing the orthogonal transformation coefficients with quantizing means, and compressing and coding the quantized orthogonal transformation coefficients with variable length coding means, the apparatus comprising:

  • means for calculating an amount of code data based on the output from said variable length coding means;

    control means for providing a reference amount of code data of the image data of one frame and sending forth a statistic process instruction and a coding process instruction after the completion of the statistic process;

    setting means for supplying to said quantizing means provisional quantization step data corresponding to the reference amount of code data supplied from said control means in the statistic process and the provisional quantization step data for a DC component of the orthogonal transformation coefficients and an optimum quantization step data for an AC component of the orthogonal transformation coefficients, the optimum quantization step data corresponding to a remainder amount of code data obtained by subtracting the amount of code data of the DC component which is quantized by using the provisional quantization step data from the reference amount of code data set by said control means;

    means for calculating an amount of code data to be assigned to each block based on an amount of code data obtained in the statistic process and the reference amount of code data; and

    means for stopping the coding operation of said variable length coding means in the coding process when the amount of code data of a block exceeds the assigned amount of code data of the block, and wherein said quantizing means quantizes the orthogonal transformation coefficients in accordance with the provisional and optimum quantization step data.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×