EP0369596A1
Expired / Lapsed
EP
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Discriminating regions of an image
Assignee: Crosfield Electronics Ltd
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Filing: 1989-10-11
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Granted: —
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Expires: 2009-10-11
Abstract
Abstract A method of discriminating between regions of an image. The image is represented by values defining the colour component content of pixels of the image and the method comprises comparing a value from each pixel with those of its neighbours to locate pixels whose values define turning points. Parts of the image where the density of turning points is greater than a threshold (19) are defined as screened regions of the image.
Inventors
- 👤 Richard Anthony Kirk
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 13:46
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/40062
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
66 words
A method of discriminating between regions of an image, the image being represented by values defining the colour component content of pixels of the image, the method comprising comparing a value from each pixel with those of its neighbours to locate pixels whose values define turning points; and discriminating (20) between regions of the image in accordance with the density of turning points in those regions.
Claim 2
Independent Claim
66 words
A method of discriminating between regions of an image, the image being represented by values defining the colour component content of pixels of the image, the method comprising comparing a value from each pixel with those of its neighbours to locate pixels whose values define turning points; and discriminating (20) between regions of the image in accordance with the density of turning points in those regions.
Claim 3
Dependent Claim
20 words
A method according to claim 1, wherein the turning points comprise one or more of maxima, minima and saddle points.
Claim 4
Dependent Claim
29 words
A method according to claim 1 or claim 2, wherein the comparison step is carried out by comparing (12,14) the digital value of the pixel with its immediate neighbours.
Claim 5
Independent Claim
47 words
A method according to any of the preceding claims further comprising following the comparison step, generating (15) a turning point map of the image in which each pixel has one of two values depending on whether it has been found to define a turning point or not.
Claim 6
Dependent Claim
45 words
A method according to claim 4, wherein all pixels in the map corresponding to pixels which are found not to define a turning point are set to zero while those pixels corresponding to pixels found to define turning points are set to a non-zero value.
Claim 7
Independent Claim
75 words
A method according to any of the preceding claims, wherein the discriminating step comprises passing a window of predetermined dimensions across the image, at each position of the window counting the number of turning points within the window, comparing the number of turning points within the window with a threshold, and, if the threshold is exceeded, causing the pixel or pixels at the centre of the window to be indicated (20) as a turning point.
Claim 8
Dependent Claim
72 words
Apparatus for discriminating between regions of an image, the image being represented by values defining the colour component content of pixels of the image, the apparatus comprising comparison means (2) for comparing a value of each pixel with those of its neighbours to locate pixels whose values define turning points; and discrimination means (2) for discriminating between regions of the image in accordance with the density of turning points in those regions.
Claim 9
Dependent Claim
72 words
Apparatus for discriminating between regions of an image, the image being represented by values defining the colour component content of pixels of the image, the apparatus comprising comparison means (2) for comparing a value of each pixel with those of its neighbours to locate pixels whose values define turning points; and discrimination means (2) for discriminating between regions of the image in accordance with the density of turning points in those regions.
Claim 10
Dependent Claim
24 words
Apparatus according to claim 7, in which the comparison and discrimination means comprise a microprocessor (2) in conjunction with a pair of stores (1,3).
References Cited (Backward Citations)
US4403257A
Cited
US4741046A
Cited
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