EP0339938B1
Expired / Lapsed
EP
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Method and system for compressing colour video encoded data
Assignee: BIL Far East Holdings Ltd
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Filing: 1989-04-25
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Granted: 1996-07-03
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Expires: 2009-04-25
Abstract
Abstract The method and system for compressing color video data in a video communication system utilizes a three color digital signal, and involves the determination of a luminance function for each pixel in a series of video picture frames. One or more decision parameters based upon differences of the luminance function between pixels are compared with corresponding adaptive thresholds to determine decision points in the scan lines, and the digital word size of the three digital color components is reduced before encoding of run lengths between decision points of the color values.
Inventors
- 👤 John Music
- 👤 James L. Thomas
- 👤 Gordon H. Smith
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 18:09
CPC Classifications
H; H04; H04N; H04N11/00; H04N11/04; H04N11/042; G; G06; G06T; G06T9/00; G06T9/005
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
317 words
A method of compressing color video data for a plurality of video picture frames, with each picture frame comprising a plurality of scan lines composed of a plurality of pixels, each scan line having a starting pixel and an ending pixel, and each pixel in said picture frame comprising three digital color component signals of first, second and third digital word sizes, respectively, said method comprising the steps of, for each pixel of at least a substantial portion of each of a plurality of scan lines: a) determining a luminance value for said pixel as a function of at least one of said three digital color component signals; b) determining at least one decision parameter representing the change in luminance for said pixel as the difference between the luminance value for said pixel and the luminance value for at least one other pixel of the same scan line; c) comparing the value of said at least one decision parameter with at least one corresponding adjustable threshold to determine whether the value of said at least one decision parameter exceeds said at least one corresponding adjustable threshold, and determining on the basis of said comparison whether said pixel represents a decision point representing a predetermined change in luminance; d) if the pixel represents a decision point, reducing the word size of at least one of said three digital color component signals to provide correspondingreduced digital color component signals for said pixel; and e) coding said pixel as one of a run length of pixels defined by a combination of a pixel run length and said corresponding digital color component signals, each said run length of pixels starting either at a starting pixel of the scan line or at a pixel representing a decision point and ending either at a pixel immediately prior to a pixel representing a decision point or at an ending pixel of the scan line.
Claim 2
Dependent Claim
71 words
The method of Claim 1, wherein said step (c) of determining whether said pixel represents a decision point further comprises the steps of: comparing the value of said at least one decision parameter with the value of said at least one decision parameter for an adjacent pixel; and if the value of said at least one decision parameter changes sign between the adjacent pixels, defining said pixel as a decision point.
Claim 3
Dependent Claim
102 words
The method of Claim 1, wherein said step (c) of determining whether said pixel represents a decision point further comprises the steps of: determining the rate of change of said at least one decision parameter between said pixel and at least one other pixel of the same scan line; comparing said rate of change with a corresponding adjustable rate of change threshold and; determining whether said rate of change exceeds said corresponding adjustable rate of change threshold and defining said pixel as a decision point if the rate of change has a predefined relationship to the corresponding adjustable rate of change threshold.
Claim 4
Dependent Claim
136 words
The method of Claim 3 wherein the step of determining the rate of change of said at least one decision parameter further comprises the steps of: determining an incremental rate of change of said at least one decision parameter between said pixel and another pixel; and accumulating said incremental rate of change with the incremental rate of change of each prior pixel that is between a previously determined decision point and said pixel, to produce a cumulative difference parameter (CUMDIFF(i)) ; the step of comparing further comprises the step of comparing said cumulative difference parameter with an adjustable cumulative difference threshold; and said step of determining whether said rate of change exceeds said corresponding adjustable rate of change threshold further comprises the step of determining whether said cumulative difference parameter exceeds said adjustable cumulative difference threshold.
Claim 5
Dependent Claim
23 words
The method of Claim 1, wherein the step of determining said luminance value includes summing each of said three digital color component signals.
Claim 6
Dependent Claim
28 words
The method of Claim 5, wherein the step of determining said luminance value includes the step of calculating a weighted sum of said three digital color component signals.
Claim 7
Dependent Claim
20 words
The method of Claim 1, wherein said one other pixel is a distance of one pixel away from said pixel.
Claim 8
Dependent Claim
20 words
The method of Claim 1, wherein said one other pixel is a distance of two pixels away from said pixel.
Claim 9
Independent Claim
34 words
The method of Claims 7 or 8, wherein a cumulative decision parameter is determined by summing the values of one of said at least one decision parameter for said pixel and one other pixel.
Claim 10
Independent Claim
36 words
The method of Claims 7 or 8, wherein a difference decision parameter is determined from the difference between the values of one of said at least one decision parameters for said pixel and one other pixel.
Claim 11
Dependent Claim
45 words
The method of Claim 1, further comprising the step of concatenating said run length of pixels with a second run length of pixels, if the said corresponding digital color component signals of said run lengths differ from each other by less than a predetermined amount.
Claim 12
Independent Claim
332 words
A system for compressing color video data for a plurality of video picture frames, with each picture frame comprising a plurality of scan lines composed of a plurality of pixels, each scan line having a starting pixel and an ending pixel and each pixel in said frame comprising three digital color component signals of first, second and third digital word sizes, respectively, said system comprising: a) means (18) for determining a luminance value for each pixel of at least a substantial portion of each of a plurality of scan lines as a function of at least one of said three digital color component signals; b) means (24) for determining at least one decision parameter representing a change in luminance for each said pixel as the difference between the luminance value for each said pixel and the luminance value for at least one other pixel of the same scan line; c) means (26) for comparing said at least one said decision parameter with at least one corresponding adjustable threshold to determine whether the value of said at least one decision parameter exceeds said at least one corresponding adjustable threshold, and for determining on the basis of said comparison whether each said pixel represents a decision point representing a predetermined change in luminance; d) means (28) for reducing the word size of at least one of said three digital color component signals, for each said pixel that represents a said decision point, to provide corresponding reduced digital color component signals for each said pixel; e) means (26) for coding each said pixel as one of a run length of pixels defined by a combination of a pixel run length and said corresponding digital color component signals, each said run length of pixels starting either at a starting pixel of the scan line or at a pixel representing a decision point and ending either at a pixel immediately prior to a pixel representing a decision point or at an ending pixel of the scan line.
Claim 13
Dependent Claim
88 words
The system of Claim 12, wherein said means (26) for determining whether said pixel represents a decision point further comprises a) means for comparing the value of said at least one decision parameter with the value of said at least one decision parameter for an adjacent pixel, and b) means for determining whether the value of said at least one decision parameter changes sign between adjacent pixels, and for defining said pixel as a decision point if the value of said at least one decision parameter changes sign.
Claim 14
Dependent Claim
114 words
The system of Claim 12, wherein said means (26) for determining whether said pixel represents a decision point further comprises: a) means for determining the rate of change of said at least one decision parameter between each said pixel and at least one other pixel of the same scan line; b) means for comparing the or each said rate of change with a corresponding adjustable rate of change threshold; and c) means for determining for whether said rate of change exceeds said corresponding adjustable rate of change threshold, and for defining said pixel as a decision point if the rate of change has a predefined relationship to the corresponding adjustable rate of change threshold.
Claim 15
Dependent Claim
26 words
The system of Claim 12, wherein said means (18) for determining said luminance value includes means for summing each of said three digital color component signals.
Claim 16
Dependent Claim
28 words
The system of Claim 15, wherein said means (18) for determining said luminance value includes means for calculating a weighted sum of said three digital color component signals.
Claim 17
Dependent Claim
46 words
The system of Claim 12, further comprising means (33) for concatenating said run length of, pixels with a second run length of pixels, if said corresponding digital color component signals of said run lengths differ from each other by less than a predetermined color difference threshold.
References Cited (Backward Citations)
No citation records indexed.
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