Device for coding a picture signal by compression

Claim 1

A picture signal compression coding device which divides digital picture data constituting a single picture into a plurality of blocks and codes the digital picture data block by block by two-dimensional orthogonal transformation, comprising: orthogonal transforming means for transforming the digital picture data divided into the plurality of blocks by a two-dimensional orthogonal transformation; normalizing means for normalizing the data transformed by said orthogonal transforming means with a normalizing coefficient common to all blocks of the single picture; coding means for coding the data normalized by said normalizing means, lower frequency components of the normalized data being coded and output before higher frequency components; block activity calculating means for calculating an activity, or degree of predominant high frequency components, of the digital picture data block by block; activity summing means for summing the block-by-block activities calculated by said block activity calculating means to produce a total activity; coded data distributing means for calculating an amount of coded data to be distributed to each of the blocks on the basis of a ratio of the block-by-block activity calculated by said block activity calculating means to the total activity produced by said activity summing means; and coded output control means for limiting the amount of coded data to be distributed to each of the blocks from said coding means in response to an output of said coded data distributing means, said block activity calculating means comprising subdividing means for subdividing each of the blocks of the digital picture data into a plurality of subblocks, subblock activity calculating means for calculating an activity of the digital picture data subblock by subblock, and difference calculating means for determining a difference between nearby subblocks with respect to a mean value of subblock-by-subblock picture data, the activities of the blocks being calculated in accordance with the subblock-by-subblock activities and the difference between nearby subblocks.

Claim 7

A method of picture signal compression coding comprising the steps of: dividing digital picture data of a single picture into a plurality of blocks in a divider; orthogonally transforming the digital picture data of each of the blocks in a two-dimensional orthogonal transformation means; normalizing the transformed digital picture data with a normalizing coefficient common to all blocks of the single picture in normalization means; coding the normalized data in a coding means, lower frequency components of the normalized data being coded and outputted before higher frequency components; calculating an activity, or degree of predominant high frequency components, of the digital picture data of each block in calculation means; summing the calculated activities of each of the blocks to generate a total activity of the single picture; calculating, in distribution means, an amount of coded data to be distributed to each of the blocks on the basis of a ratio of the activity of the particular block and the total activity of the single picture; and generating a limiting signal, in coded output control means, which limits the amount of coded data of each of the blocks output by the coding means in response to said calculating of an amount, the activity of each block being calculated in accordance with calculated subblock activities and a difference between nearby subblocks.

Claim 8

A method of picture signal compression coding comprising the steps of: dividing digital picture data of a single picture into a plurality of blocks in a divider; orthogonally transforming the digital picture data of each of the blocks in a two-dimensional orthogonal transformation means; normalizing the transformed digital picture data with a normalizing coefficient common to all blocks of the single picture in normalization means; coding the normalized data in a coding means, lower frequency components of the normalized data being coded and outputted before higher frequency components; calculating an activity, or degree of predominant high frequency components, of the digital picture data of each block in calculation means; summing the calculated activities of each of the blocks to generate a total activity of the single picture; calculating, in distribution means, an amount of coded data to be distributed to each of the blocks on the basis of a ratio of the activity of the particular block and the total activity of the single picture; and generating a limiting signal, in coded output control means, which limits the amount of coded data of each of the blocks output by the coding means in response to said calculating of an amount, the activity of each block being calculated in accordance with calculated subblock activities and a difference between nearby subblocks.