Patent EP0370718A1 successfully refreshed from Google Patents.
EP0370718A1
Expired / Lapsed
EP
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Data compression
Assignee: Crosfield Electronics Ltd
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Filing: 1989-11-20
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Granted: —
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Expires: 2009-11-20
Abstract
Abstract A method of compressing digital image or image-like pixel data. The method comprises carrying out the following steps on small blocks of pixels: a) determining (20) the differences between digital values of adjacent pixels in the block to define respective link weights; b) determining (21) a tree connecting all the pixels in the block such that the sum of the link weights in the tree is a minimum; c) dividing (22) the tree into segments by removing links with weights greater than a threshold value, so dividing the block into segments of linked pixels; d) generating a segmented representation of the block by setting the values of all pixels in each segment to a single, respective, representational value; and e) compressing (24) the segmented representation to generate compressed data.
Inventors
- 👤 Richard Anthony Kirk
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 13:52
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/41
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
129 words
A method of compressing digital image or image-like pixel data, the method comprising carrying out the following steps on small blocks of pixels: a) determining (20) the differences between digital values of adjacent pixels in the block to define respective link weights; b) determining (21) a tree connecting all the pixels in the block such that the sum of the link weights in the tree is a minimum; c) dividing (22) the tree into segments by removing links with weights greater than a threshold value, so dividing the block into segments of linked pixels; d) generating a segmented representation of the block by setting the values of all pixels in each segment to a single, respective, representational value; and e) compressing (24) the segmented representation to generate compressed data.
Claim 2
Independent Claim
129 words
A method of compressing digital image or image-like pixel data, the method comprising carrying out the following steps on small blocks of pixels: a) determining (20) the differences between digital values of adjacent pixels in the block to define respective link weights; b) determining (21) a tree connecting all the pixels in the block such that the sum of the link weights in the tree is a minimum; c) dividing (22) the tree into segments by removing links with weights greater than a threshold value, so dividing the block into segments of linked pixels; d) generating a segmented representation of the block by setting the values of all pixels in each segment to a single, respective, representational value; and e) compressing (24) the segmented representation to generate compressed data.
Claim 3
Dependent Claim
35 words
A method according to claim 1, further comprising generating (23) a texture representation of the block constituted by the differences between each actual pixel value in the block and the corresponding segmented representation pixel value.
Claim 4
Dependent Claim
12 words
A method according to claim 2, further comprising compressing the texture representation.
Claim 5
Dependent Claim
16 words
A method according to claim 3, wherein the texture representation is compressed using a thresholding technique.
Claim 6
Independent Claim
22 words
A method according to any of the preceding claims, wherein the segmented representation is compressed using a run link or quadtree compression.
Claim 7
Independent Claim
23 words
A method according to any of the preceding claims, wherein the representational value is the average of the pixel values in the segment.
Claim 8
Dependent Claim
123 words
Apparatus for compressing digital image or image-like pixel data, the apparatus comprising means for determining (20) the differences between digital values of adjacent pixels in the block to define respective link weights; means for determining (21) a tree connecting all the pixels in the block such that the sum of the link weight in the tree is a minimum; means for dividing (22) the tree into segments by removing links with weights greater than a threshold value, so dividing the block into segments of linked pixels; means for generating a segmented representation of the block by setting the values of all pixels in each segment to a single, respective, representational value; and means for compressing (24) the segmented representation to generate compressed data.
Claim 9
Dependent Claim
123 words
Apparatus for compressing digital image or image-like pixel data, the apparatus comprising means for determining (20) the differences between digital values of adjacent pixels in the block to define respective link weights; means for determining (21) a tree connecting all the pixels in the block such that the sum of the link weight in the tree is a minimum; means for dividing (22) the tree into segments by removing links with weights greater than a threshold value, so dividing the block into segments of linked pixels; means for generating a segmented representation of the block by setting the values of all pixels in each segment to a single, respective, representational value; and means for compressing (24) the segmented representation to generate compressed data.
Claim 10
Dependent Claim
36 words
Apparatus according to claim 7, further comprising means for generating (23) a texture representation of the block constituted by the differences between each actual pixel value in the block and the corresponding segmented representation pixel value.
Claim 11
Dependent Claim
13 words
Apparatus according to claim 8, further comprising means for compressing the texture representation.
References Cited (Backward Citations)
FR2262348A1
Cited
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