Encoding of motion picture signal

• US 5,258,836 A
• Filed: 05/05/1992
• Issued: 11/02/1993
• Est. Priority Date: 05/08/1991
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Murata, Eri
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US07/878,471
• Time in Patent Office: 546 Days
• Field of Search: 358/136, 358/105, 358/85, 379/53
• US Class Current: 348/415.1
• CPC Class Codes: H04N 19/20 using video object coding
• CPC Class Codes: H04N 19/503 involving temporal prediction adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109
• CPC Class Codes: H04N 19/98 Adaptive-dynamic-range coding [ADRC]

Abstract

A valid/invalid detection section 1 generates an original valid block map based on a difference between frames. The current and previous valid block maps are weighted within weight sections 2 and 3 respectively and are thereafter summed up to compose them. After isolated valid blocks are removed from the composed valid block map within a segmentation section 5, it is determined whether or not a moving object exists and the direction of the moving object is determined based on the distribution of the valid block map. If a significant movement is detected, then blocks around the object are weighted at the movement direction side. Another segmentation section 7 determines valid blocks with reference to interest blocks and neighbor blocks, and isolated invalid block section 8 removes isolated invalid blocks to generate a complete valid block map. Encoding is performed based on the complete valid block map.

Claims

1. A motion picture signal encoding method utilizing a correlation between images of an N-th frame and an (N-1)-th, N being an integer larger than one, said method comprising the steps of:

(a) generating a first valid block map for said N-th frame, by dividing images of said (N-th) frame and corresponding (N-1)-th frame into blocks of a plurality of picture elements, detecting for each of said blocks, a difference between said images of said N-th frame and said (N-1)-th frame, making each of said blocks a valid block, if said difference of said blocks is larger than or equal to a predetermined first threshold value, and making each of said blocks and invalid block, if said difference of said blocks is less than said first threshold value;

(b) generating a second valid block map for said N-th frame, be weighting said first valid block map with a first weighting factor, weighting a complete valid block map generated for said (N-1)-th frame with a second weighting factor, and composing said weighted first and complete valid block maps by sum operations;

(c) generating a third valid block map for said N-th frame, by making each of said valid blocks of said second valid block map an invalid block, if a sum of values of said valid blocks and neighboring blocks is less than a predetermined second threshold value;

(d) generating a fourth valid block map for said N-th frame, by,

obtaining a sum of values of said valid blocks at the most left locations along horizontal block lines in said third valid block map, obtaining a sum of values of said valid blocks at the most right locations along horizontal block lines in said third valid block map, if a difference between said sums is larger than or equal to a third threshold value, then weighting said valid blocks at the most left or right locations having the greater sum with a third weighting factor and further making each of said blocks of said third valid block map thus weighed a valid block, provided that, a sum of values of said blocks and said neighboring blocks is larger than or equal to a fourth threshold value and making each of said blocks of said third valid block map thus weighed an invalid block, provided that, a sum of values of said block and said neighboring blocks is less than said fourth threshold value to generate said fourth valid block map;

if said difference between said sums is less than said third threshold value, then making each of said blocks of said third valid block map a valid block, provided that, a sum of values of said blocks and said neighboring blocks is larger than or equal to a fifth threshold value and making each of said blocks of said third valid block map an invalid block, provided that, a sum of values of said blocks and said neighboring blocks is less than said fifth threshold value to generate said fourth valid block map;

(e) generating said complete valid block map for said N-th frame, by making each of said invalid blocks of said fourth valid block map a valid block, if a sum of values of said neighboring blocks is larger than or equal to a predetermined sixth threshold value;

(f) encoding only a part of said image of said frame corresponding to said valid blocks of said complete valid block map by using correlations between N-th and (N-1)-th images and/or in an image; and

(g) repeating said steps (a) through (f) with said N being replaced with (N+1).

2. A motion picture signal encoding method according to claim 1, wherein said threshold values are determined statistically.

3. A motion picture signal encoding method according to claim 2, wherein said neighboring blocks are eight blocks adjacent to a block to be processed.

4. A motion picture signal encoding apparatus utilizing a correlation between images, comprising:

means for generating a first valid block map for each frame, by dividing images of said frame and corresponding reference frame into blocks of a plurality of picture elements, detecting for each of said blocks difference between said images of said frame and said reference frame, making each of said blocks a valid block if said difference of said block is larger than or equal to a predetermined first threshold value, and making said block an invalid block if said difference of said block is less than said first threshold value;

means for generating a second valid block map for each of said frames, by weighting said first valid block map with a first weighting factor, weighting a complete valid block map generated for a previous frame with a second factor, and composing said weighted first and complete valid block maps by sum operations;

means for generating a third valid block map for each of said frames, by making each of said valid block of said second valid block map an invalid block if a sum of values of said valid block and neighbor blocks is less than a predetermined second threshold value;

means for generating a fourth valid block map for each of said frames, by,

obtaining a sum of values of valid blocks at the most left locations along horizontal block lines in said third valid block map, obtaining a sum of values of valid blocks at the most right locations along horizontal block lines in said third valid block map.

if a difference between said sums is larger than or equal to a third threshold value then weighting valid blocks at the most left or right locations having the greater sum with a third weighting factor and further making each block of said third valid block map thus weighted a valid block provided that a sum of values of said block and neighbor blocks is larger than or equal to a fourth threshold value and making each of said block of said third valid block map thus weighted an invalid block provided that a sum of values of said block and neighbor blocks is less than said fourth threshold value to generate said fourth valid block map;

if said difference between said sums is less than said third threshold value then making each block of said third valid block map a valid block provided that a sum of values of said block and neighbor blocks is larger than or equal to a fifth threshold value and making each of said block of said third valid block map an invalid block provided that a sum of values of said block and neighbor blocks is less than said fifth threshold value to generate said fourth valid block map;

means for generating said complete valid block map for each of said frames, by making each of invalid blocks of said fourth valid block map a valid block if a sum of values of neighbor blocks is larger than or equal to a predetermined sixth threshold value; and

means for encoding only a part of said image of said frame corresponding to valid blocks of said complete valid block map by using correlations between images and/or in a image.

5. A motion picture signal encoding method, comprising the steps of:

(a) receiving an inputted motion picture signal for a N-th frame, N being an integer larger than one;

(b) locating an area covering an interest part of said motion picture signal for said N-th frame, wherein said locating step includes the steps of;

generating a first valid block map for said N-th frame, by dividing images of said N-th frame and corresponding (N-1)-th frame into blocks of a plurality of picture elements, detecting for each of said blocks, a difference between said images of said N-th frame and said (N-1)-th frame, making each of said blocks a valid block, if said difference of each of said blocks is larger than or equal to a predetermined first threshold value, and making each of said blocks an invalid block, if said difference of each said blocks is less than said first threshold value;

generating a second valid block map for said N-th frame, by weighting said first valid block map with a first weighting factor, weighting a complete valid block map generated for said (N-1)-th frame with a second weighting factor, and composing said weighted first and complete valid blocks map by sum operations;

generating a third valid block map for said N-th frame, by making each of said valid block of said second valid block map an invalid block, if a sum of values of said valid blocks and said neighboring blocks is less than a predetermined second threshold;

detecting a movement direction of said interest part; and

generating a fourth valid block map for said N-th frame, by weighting said valid blocks of said third valid block map, according to said movement direction thus detected, and further making each of said blocks of said third valid block map thus weighed a valid block, provided that, a sum of values of said blocks and said neighboring blocks is larger than or equal to a fourth threshold value and making each of said blocks of said third valid block map thus weighed an invalid block, provided that, a sum of values of said blocks and said neighboring blocks is less than said fourth threshold value to generate value to generate said fourth valid block map,

said valid blocks of said fourth valid block map being located as said area covering said interest part;

(c) responsive to said located area, extracting said interest part from said motion picture signal for said N-th frame;

(d) encoding only said interest part of said motion picture signal thus extracted by using correlations between N-th and (N-1)-th images and/or in an image; and

(e) repeating said steps (a) through (d) with said N being replaced with (N+1).