US4823190A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for enhancing contours of television signal
Assignee: Ikegami Tsushinki Co Ltd
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Filing: 1987-03-31
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Granted: 1989-04-18
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Expires: 2007-03-31
Abstract
Abstract An apparatus for effecting contour enhancement in a non-linear manner, in accordance with the 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 the contour for a brightness signal having a small level difference can be enhanced sufficiently.
Inventors
- 👤 Kazumi Yamamoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 23:17
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/14; H04N5/142
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
145 words
An apparatus for enhancing contours of an image signal having a color subcarrier, comprising: contour signal producing means for extracting a contour signal from an image signal whose contours are to be enhanced; means for filtering said contour signal to produce a filtered contour signal, said means for filtering having a center frequency near the color subcarrier frequency and having a figure of merit Q; means for selectively changing the figure of merit Q, said means for selectively changing the figure of merit Q including a series combination of a resistor and a semiconductor switch, the series combination being connected to the means for filtering; contour enhancement signal producing means for processing said filtered contour signal non-linearly in accordance with the amplitude of the filtered contour signal to derive a contour enhancement signal; and means for adding said contour enhancement signal to said image signal.
Claim 2
Independent Claim
145 words
An apparatus for enhancing contours of an image signal having a color subcarrier, comprising: contour signal producing means for extracting a contour signal from an image signal whose contours are to be enhanced; means for filtering said contour signal to produce a filtered contour signal, said means for filtering having a center frequency near the color subcarrier frequency and having a figure of merit Q; means for selectively changing the figure of merit Q, said means for selectively changing the figure of merit Q including a series combination of a resistor and a semiconductor switch, the series combination being connected to the means for filtering; contour enhancement signal producing means for processing said filtered contour signal non-linearly in accordance with the amplitude of the filtered 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 the gain of the contour enhancement signal for an image signal having a large level difference is reduced relative to the gain of a contour enhancement signal for an image signal having a small level difference.
Claim 4
Dependent Claim
49 words
An apparatus according to claim 1, wherein said contour enhancement signal producing means comprises an upper limiter for clipping a portion of the filtered contour signal exceeding an upper threshold level and a lower limiter for clipping a portion of the filtered 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 comprises means for adjusting said upper and lower threshold levels.
Claim 6
Dependent Claim
52 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 filtered contour signal exceeding an upper threshold level, and a second compression unit for compressing a portion of the filtered 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
25 words
An apparatus according to claim 3, further comprising a threshold circuit means for suppressing a portion of the filtered contour signal below a threshold level.
Claim 10
Dependent Claim
18 words
An apparatus according to claim 8, wherein said threshold circuit means comprises means for adjusting said threshold level.
Claim 11
Dependent Claim
26 words
An apparatus according to claim 3, further comprising means for changing the gain of the contour enhancement signal in accordance with a position on an image.
Claim 12
Dependent Claim
78 words
An apparatus according to claim 1, wherein said image signal has a changeable signal level, wherein said filtered contour signal has a constant value when the level of the image signal does not change and has positive and negative portions with respect to the constant value if the level of the image signal does change, and wherein said contour enhancement signal producing means processes said filtered contour signal non-linearly by processing both the positive and negative portions non-linearly.
Claim 13
Independent Claim
192 words
An apparatus for enhancing contours of an image signal having a color subcarrier, comprising: contour signal producing means for extracting a contour signal from an image signal whose contours are to be enhanced; means for filtering said contour signal to produce a filtered contour signal, said means for filtering having a center frequency near the color subcarrier frequency and having a figure of merit Q; means for selectively changing the figure of merit Q; contour enhancement signal producing means for processing said filtered contour signal non-linearly in accordance with the amplitude of the filtered contour signal to derive a contour enhancement signal, said contour enhancement signal producing means including an upper limiter for clipping a portion of the filtered contour signal exceeding an upper threshold level and a lower limiter for clipping a portion of the filtered contour signal below a lower threshold level; means for changing the gain of the contour enhancement signal in accordance with a position on an image, said means for changing the gain including means for increasing the gain toward the periphery of the image; and means for adding said contour enhancement signal to said image signal.
Claim 14
Independent Claim
192 words
An apparatus for enhancing contours of an image signal having a color subcarrier, comprising: contour signal producing means for extracting a contour signal from an image signal whose contours are to be enhanced; means for filtering said contour signal to produce a filtered contour signal, said means for filtering having a center frequency near the color subcarrier frequency and having a figure of merit Q; means for selectively changing the figure of merit Q; contour enhancement signal producing means for processing said filtered contour signal non-linearly in accordance with the amplitude of the filtered contour signal to derive a contour enhancement signal, said contour enhancement signal producing means including an upper limiter for clipping a portion of the filtered contour signal exceeding an upper threshold level and a lower limiter for clipping a portion of the filtered contour signal below a lower threshold level; means for changing the gain of the contour enhancement signal in accordance with a position on an image, said means for changing the gain including means for increasing the gain toward the periphery of the image; and means for adding said contour enhancement signal to said image signal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-04-17 | 1992-10-17 | 1993-04-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-17 | 1996-10-17 | 1997-04-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-17 | 2000-10-17 | 2001-04-18 | $7700.00 | Window Closed / Lapsed |