Device for coding a picture signal by compression

• US 5,101,280 A
• Filed: 05/17/1990
• Issued: 03/31/1992
• Est. Priority Date: 05/19/1989
• Status: Expired due to Term

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Watanabe, Mikio, Ito, Kenji, Moronaga, Kenji
• Primary Examiner(s): Coles, Sr., Edward L.
• Assistant Examiner(s): LEE, TOMMY D
• Application Number:
  US07/524,389
• Time in Patent Office: 684 Days
• Field of Search: 358/426, 358/432, 358/433, 358/133, 358/138, 382/50, 382/54
• US Class Current: 382/239
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/149 by estimating the code amount by means of a model, e.g. mathematical model or statistical model
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/18 the unit being a set of transform coefficients
• CPC Class Codes: H04N 19/60 using transform coding

Abstract

A picture signal compression coding device is disclosed which divides digital picture data constituting a single picture into a plurality of blocks and codes the picture data block by block by two-dimensional orthogonal transformation. An orthogonal transforming section transforms the digital picture data divided into the plurality of blocks by two-dimensional orthogonal transformation. A normalizing section normalizes the transformed data, while a coding section codes the normalized data. A block activity calculating section calculates an activity of the picture data block by block. An activity summing section sums the block-by-block activities to produce a total activity. A coded data distributing section calculates an amount of coded data to be distributed to each of the blocks on the basis of the ratio of the block-by-block activity to the total activity. A coded output control section limits the amount of coded data to be distributed to each of the blocks from the coding section in response to an output of the coded data distributing section. The block activity calculating section has a subdividing section for subdividing each of the blocks of picture data into a plurality of subblocks, a subblock activity calculating section for calculating the activity of the picture data subblock by subblock, and a difference calculating section for determining a difference between nearby ones of the subblocks with respect to the mean value of subblock-by-subblock picture data.

Claims

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.

2. The picture signal compression coding device in accordance with claim 1, wherein said block activity calculating means calculates the activity of each of the blocks by summing up the subblock-by-subblock activities determined by said subblock activity calculating means and a sum of the differences between nearby subblocks determined by said difference calculating means.

3. The picture signal compression coding device in accordance with claim 2, wherein said block activity calculating means triples the sum of the differences between nearby subblocks and adds said tripled sum to a sum of the subblock-by-subblock activities.

4. The picture signal compression coding device in accordance with claim 2, wherein each of the blocks is subdivided into four subblocks, the sum of the differences between the subblocks being the sum of four differences between nearby ones of said four subblocks.

5. The picture signal compression coding device in accordance with claim 3, wherein each of the blocks is subdivided into four subblocks, the sum of the differences between the subblocks being the sum of four differences between nearby ones of said four subblocks.

6. 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.

7. The method of picture signal compression coding of claim 6, said step of calculating an activity of each of the blocks comprising summing the calculated subblock activities and a sum of differences between adjacent subblocks.

8. The method of picture signal compression coding of claim 7, said step of calculating an activity of each of the blocks further comprising tripling the sum of differences between adjacent subblocks.