Patent ID: 7369706
Filing Date: 2008-05-06
Classification: G06T

Abstract:
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.