EP0241246A2
Expired / Lapsed
EP
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Apparatus for enhancing contours of television signal
Assignee: Ikegami Tsushinki Co Ltd
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Filing: 1987-04-03
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Granted: —
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Expires: 2007-04-03
Abstract
Abstract An apparatus for effecting a contour enhancement in a non-linear manner in accordance with an amplitude of a contour signal includes an upper limiter for clipping a portion of the contour signal exceeding an upper level and a lower limiter for clipping a portion of the contour signal below a lower level. The gain of the contour signal for a brightness signal having a large level difference is decreased relative to the gain of the contour enhancement signal for a brightness signal having a small level difference, and thus glare and cross-color noise can be reduced materially, while a contour of the brightness signal having a small level difference can be enhanced sufficiently.
Inventors
- 👤 Kazumi Yamamoto
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 18:06
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/14; H04N5/142
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
67 words
An apparatus for enhancing contours of an image signal comprising contour signal producing means for extracting a contour signal from an image signal whose contours are to be enhanced; contour enhancement signal producing means for processing said contour signal non-linearly in accordance with an amplitude of the contour signal to derive a contour enhancement signal; and means for adding said contour enhancement signal to said image signal.
Claim 2
Independent Claim
67 words
An apparatus for enhancing contours of an image signal comprising contour signal producing means for extracting a contour signal from an image signal whose contours are to be enhanced; contour enhancement signal producing means for processing said contour signal non-linearly in accordance with an amplitude of the contour signal to derive a contour enhancement signal; and means for adding said contour enhancement signal to said image signal.
Claim 3
Dependent Claim
53 words
An apparatus according to claim 1, wherein said contour enhancement signal producing means is constructed such that a gain of the contour enhancement signal for an image signal having a large level difference is reduced relative to a gain of a contour enhancement signal for an image signal having a small level difference.
Claim 4
Dependent Claim
47 words
An apparatus according to claim 2, wherein said contour enhancement signal producing means comprises an upper limiter for clipping a portion of the contour signal exceeding an upper threshold level and a lower limiter for clipping a portion of the contour signal below a lower threshold level.
Claim 5
Dependent Claim
24 words
An apparatus according to claim 3, wherein said contour enhancement signal producing means further comprising means for adjusting said upper and lower threshold levels.
Claim 6
Dependent Claim
50 words
An apparatus according to claim 2, wherein said contour enhancement signal producing means comprises a first compression unit for compressing a portion of the contour signal exceeding an upper threshold level, and a second compression unit for compressing a portion of the contour signal smaller than a lower threshold level.
Claim 7
Dependent Claim
27 words
An apparatus according to claim 5, wherein said first and second compression units comprise first and second means for adjusting said upper and lower threshold levels, respectively.
Claim 8
Dependent Claim
23 words
An apparatus according to claim 6, wherein said first and second compression units further comprise first and second means for adjusting compression rates.
Claim 9
Dependent Claim
26 words
An apparatus according to claim 3, wherein said contour enhancement signal producing means further comprises a circuit for controlling a frequency characteristic of the contour signal.
Claim 10
Dependent Claim
30 words
An apparatus according to claim 8, wherein said frequency characteristic controlling circuit comprises a resonance circuit and means for selectively changing a figure of merit Q of said resonance circuit.
Claim 11
Dependent Claim
30 words
An apparatus according to claim 3, wherein said contour enhancement signal producing means further comprises a threshold circuit for suppressing a portion of the contour signal below a threshold level.
Claim 12
Dependent Claim
17 words
An apparatus according to claim 10, wherein said threshold circuit comprises means for adjusting said threshold level.
Claim 13
Dependent Claim
33 words
An apparatus according to claim 3, wherein said contour enhancement signal producing means further comprises means for changing the gain of the contour enhancement signal in accordance with a position on an image.
References Cited (Backward Citations)
No citation records indexed.
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