Patent EP0797349A2 successfully refreshed from Google Patents.
EP0797349A2
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EP
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Signal adaptive postprocessing system for reducing blocking effects and ringing noise
Assignee: Samsung Electronics Co Ltd
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Filing: 1996-09-23
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Granted: —
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Expires: 2016-09-23
Abstract
Abstract A signal adaptive filtering method is provided to reduce blocking effects caused by decompression of the block-based compressed images, including the steps of generating binary edge map information by globally thresholding and locally thresholding the decompressed image; judging whether the binary edge map information within a filter window corresponding to respective pixels is either homogeneous area or edge area, by using the binary edge map information belonging to a predetermined size of the filter window; generating a filtered pixel value corresponding to a respective pixel using the filter window which has a predetermined first weight factors related to the homogeneous area, when the binary edge map information is judged as the homogeneous area in the second step; altering the predetermined second weight factors according to a binary edge map information included in the filter window when the binary edge map information is judged as the edge area in the second step; and generating a filtered pixel value corresponding to the respective pixel, using the filter window which has altered second weight factors in said fourth step. A corresponding apparatus is also disclosed.
Inventors
- 👤 Yung-Lyul Lee
- 👤 Hyun-Wook Park
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 11:24
CPC Classifications
H; H04; H04N; H04N19/00; H04N19/85; H04N19/50; H04N19/503; H04N19/51; H04N19/527; G; G06; G06T; G06T5/00; G06T5/20; H04N19/86
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
184 words
A signal adaptive filtering method for reducing blocking effects and ringing noise of a decompressed digital image, said signal adaptive filtering method comprising the steps of (a) generating binary edge map information by globally thresholding and locally thresholding the decompressed image; (b) judging whether the binary edge map information within a filter window corresponding to respective pixels is either homogeneous area or edge area, by using the binary edge map information belonging to a predetermined size of the filter window; (c) generating a filtered pixel value corresponding to a respective pixel using the filter window which has a predetermined first weight factors relating to the homogeneous area, when the binary edge map information is judged as the homogeneous area in said step (b); (d) altering the predetermined second weight factors according to a binary edge map information corresponding to the respective pixel when the binary edge map information is judged as the edge area in said step (b); and (e) generating a filtered pixel value corresponding to the respective pixel, using the filter window which has altered second weight factors in said step (d).
Claim 2
Dependent Claim
148 words
A signal adaptive filtering method according to claim 1, wherein said step (a) comprises the steps of : (a1) generating a gradient image corresponding to the decompressed image; (a2) generating global edge map information which is composed of edge values corresponding to the respective pixels of the decompressed image, by comparing a predetermined first thresholding value with a gradient value corresponding to the respective pixels within the gradient image; (a3) generating local edge map information which is composed of edge values corresponding to the respective pixels of the decompressed image, by comparing gradient values within a predetermined size of individual blocks into which the decompressed image is divided, with a predetermined second thresholding value corresponding to the block; and (a4) logically summing an edge value in the global edge map information and a corresponding edge value in the local edge map information, and generating binary edge map information.
Claim 3
Dependent Claim
125 words
A signal adaptive filtering method according to claim 1 or claim 2, wherein said step (a3) calculates the second thresholding value corresponding to respective blocks using the following equation : T n =|1- σ n m n | x T g wherein, σ N = 1 N ( i , j )∈ R n g ( i , j )- m n 2 m n = 1 N ( i , j )∈ R n g ( i , j ) Here, g(i,j) represents a gradient value, R n represents an n-th 8x8 block region, m n and σ n represent an average deviation and a standard deviation of an n-th 8x8 block of the gradient image, and T g represents a global threshold value.
Claim 4
Dependent Claim
38 words
A signal adaptive filtering method according to claim 3, therein said step (a3) compares the gradient values corresponding to 6x6 pixels within a 8x8 block excluding boundary pixels within the 8x8 block with the corresponding second thresholding value.
Claim 5
Dependent Claim
38 words
A signal adaptive filtering method according to any preceding claim, wherein the more said predetermined second weight factors move from the centre of the filter window to the boundary thereof, the less said predetermined second weight factors have.
Claim 6
Dependent Claim
17 words
A signal adaptive filtering method according to claim 5, wherein said filter window has a 5x5 size.
Claim 7
Dependent Claim
39 words
A signal adaptive filtering method according to claim 6, wherein said step (c) uses a filter window in which first weight factors positioned at four corners are "0" in magnitude, and those positioned at the remaining points are "1".
Claim 8
Dependent Claim
61 words
A signal adaptive filtering method according to claim 6, wherein a second weight factor located in the centre of the said filter window is "3" in magnitude, and second weight factors located at the others thereof are less than "2", wherein the closer the second weight factors are to boundary of the filter window, the less the second weight factors become.
Claim 9
Dependent Claim
61 words
A signal adaptive filtering method according to claim 6, wherein a second weight factor located in the centre of said filter window is "4" in magnitude, and second weight factors located at the others thereof are less than "2", wherein the closer the second weight factors are to edge points of the filter window, the less the second weight factors become.
Claim 10
Dependent Claim
51 words
A signal adaptive filtering method according to any one of claims 1-5, wherein said step (d) comprises the step of changing, to zero, the second weight factors which are located at the edge point and outer neighbouring points of the edge point, based on the edge point within the filter window.
Claim 11
Dependent Claim
20 words
A signal adaptive filtering method according to any one of claims 1-5, wherein said filter window has a 3x3 size.
Claim 12
Dependent Claim
25 words
A signal adaptive filtering method according to claim 11, wherein said step (c) uses the filter window having the same magnitude of first weight factors.
Claim 13
Dependent Claim
16 words
A signal adaptive filtering method according to claim 12, wherein said first weight factor is "1".
Claim 14
Dependent Claim
37 words
A signal adaptive filtering method according to claim 11, wherein a second weight factor located in the center of said filter window is "2" in magnitude, and second weight factors located at the others thereof are "1".
Claim 15
Dependent Claim
37 words
A signal adaptive filtering method according to claim 11, wherein a second weight factor located in the centre of said filter window is "3" in magnitude, and second weight factors located at the others thereof are "1".
Claim 16
Dependent Claim
79 words
A signal adaptive filtering method according to claim 11, wherein said step (d) comprises the step of resetting, as zero, second weight factors corresponding to positions put on a diagonal line and second weight factors corresponding to the outer neighbour of positions placed on the diagonal line, if the binary edge map information which corresponds to positions on the diagonal lines among the positions excluding the central points of the 3x3 filter window is represented as all edge points.
Claim 17
Dependent Claim
35 words
A signal adaptive filtering method according to any preceding claim, wherein said step (e) performs no filtering operation with regard to corresponding pixels if the central point within said filter window is an edge point.
Claim 18
Dependent Claim
28 words
A filtering method comprising the steps of generating a filtered pixel value using a filter window weighted according to whether the filter window corresponds to an edge area.
Claim 19
Dependent Claim
30 words
A filtering method according to claim 18, which method further comprises any one or more feature or step disclosed in the accompanying description, claims, abstract and/or drawings, in any combination.
Claim 20
Dependent Claim
11 words
A filtering apparatus adapted to operate according to any preceding claim.
References Cited (Backward Citations)
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