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Image-data processing device, image-data processing method, image-data distributing device and image-data transmitting system

  • US 20040151393A1
  • Filed: 12/30/2003
  • Published: 08/05/2004
  • Est. Priority Date: 01/06/2003
  • Status: Active Grant
First Claim
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1. An image-data processing device, in which an original image is divided into a plurality of blocks that are made up of a plurality of picture elements, and in each block, from encoded image-data which is obtained by encoding a spatial-frequency component of the block as a plurality of spatial-frequency coefficients, reduced encoded image-data is produced which is encoded data on a reduced image that is obtained by reducing the original image to a given reduction rate, comprising:

  • a block abstracting means for abstracting each block as a block to be processed, one after another, from the plurality of blocks;

    a DC-coefficient abstracting means for abstracting a direct-current component coefficient from the plurality of spatial-frequency coefficients of the block to be processed;

    an adjacent DC-coefficient abstracting means for abstracting the direct-current component coefficient of at least one adjacent block which is adjacent, in any of a horizontal direction, a vertical direction and an oblique direction, to the block to be processed, as at least one adjacent direct-current component coefficient;

    a DC-coefficient comparing means for comparing the direct-current component coefficient of the block to be processed and the at least one adjacent direct-current component coefficient, and calculating a value of a predetermined function of the direct-current component coefficient of the block to be processed and the at least one adjacent direct-current component coefficient, the function representing an extent of unevenness between the direct-current component coefficient of the block to be processed and the at least one adjacent direct-current component coefficient;

    a coefficient-set setting means for, if the value of the function is larger than a predetermined value, holding a smaller number of spatial-frequency coefficients than the plurality of spatial-frequency coefficients of the block to be processed according to the reduction rate, which have lower frequencies and include the direct-current component coefficient among the plurality of spatial-frequency coefficients of the block to be processed, and setting the other spatial-frequency coefficients to zero; and

    a DC-coefficient setting means for, if the value of the function is smaller than the predetermined value, holding only the direct-current component coefficient of the plurality of spatial-frequency coefficients of the block to be processed, and setting the other spatial-frequency coefficients to zero.

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