US6271891B1
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US
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Video signal processing circuit providing optimum signal level for inverse gamma correction
Assignee: Pioneer Corp
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Filing: 1999-06-18
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Granted: 2001-08-07
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Expires: 2019-06-18
Abstract
Abstract A video signal processing circuit in which nearly 100% of a largest possible dynamic range can be used, desired contrast is obtained, and desired brightness characteristics are obtained by an increasing in luminance of a screen. The circuit has an RGB amplifier which amplifies three primary color video signals R, G, and B by a predetermined gain and in which the gain is controlled by a gain control signal, A/D converters for converting analog three primary color video signals which are generated from the RGB amplifier into digital signals respectively, inverse gamma correcting circuits for effecting an inverse gamma correction to the three primary color digital video signals respectively, an OR circuit and a peak holding circuit for detecting peak levels of the analog three primary color signals, and a gain control signal generator for generating a gain control signal in accordance with the peak levels. When the peak levels are equal to or larger than a predetermined value, the gain control signal generator supplies the gain control signal to control the RGB amplifier so as to set the level of each of the three primary color digital video signals generated by the A/D converters at a peak value.
Inventors
- 👤 Shuji Ogawa
- 👤 Hirofumi Kawaguchi
- 👤 Nozomu Kikuchi
- 👤 Junichi Usui
- 👤 Masayuki Takeda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:56
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/68; H04N9/69; G; G09; G09G; G09G2320/00; G09G2320/02; G09G2320/0271; G09G3/00; G09G3/20
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
217 words
A video signal processing circuit comprising: peak level detecting means for detecting peak levels of three primary color video signals of red, green, and blue indicative of video information; inverse gamma correcting circuits for effecting an inverse gamma correction to three primary color input video signals according to said three primary color video signals, respectively; and a level control circuit for controlling a signal level of each of said three primary color input video signals which are supplied to said inverse gamma correcting circuits in accordance with said detected peak levels, wherein when at least one of said peak levels is equal to or larger than a predetermined value, said level control circuit performs a control operation to set a level of each of the three primary color input video signals which are supplied to said inverse gamma correcting circuit to a peak value, and when the peak levels are less than the predetermined value, said level control circuit performs a control operation in which each of the three primary color input video signals which are supplied to said inverse gamma correcting circuit is set to a signal level obtained by multiplying each of the three primary color video signals of red, green, and blue representing said video information by a predetermined coefficient of “1” or more.
Claim 2
Dependent Claim
217 words
A video signal processing circuit comprising: peak level detecting means for detecting peak levels of three primary color video signals of red, green, and blue indicative of video information; inverse gamma correcting circuits for effecting an inverse gamma correction to three primary color input video signals according to said three primary color video signals, respectively; and a level control circuit for controlling a signal level of each of said three primary color input video signals which are supplied to said inverse gamma correcting circuits in accordance with said detected peak levels, wherein when at least one of said peak levels is equal to or larger than a predetermined value, said level control circuit performs a control operation to set a level of each of the three primary color input video signals which are supplied to said inverse gamma correcting circuit to a peak value, and when the peak levels are less than the predetermined value, said level control circuit performs a control operation in which each of the three primary color input video signals which are supplied to said inverse gamma correcting circuit is set to a signal level obtained by multiplying each of the three primary color video signals of red, green, and blue representing said video information by a predetermined coefficient of “1” or more.
Claim 3
Dependent Claim
194 words
A video signal processing circuit comprising: a gain control amplifier which amplifies each of analog three primary color video signals of red, green, and blue indicative of video information by a predetermined gain and in which said gain is controlled by a gain control signal; analog/digital converters for converting said analog three primary color video signals which are generated from said gain control amplifier into digital signals, respectively; inverse gamma correcting circuits for effecting an inverse gamma correction to said three primary color digital video signals, respectively; a peak level detecting circuit for detecting a peak level of each of the analog three primary color video signals which are supplied to said analog/digital converters; and a gain control signal generator for generating said gain control signal in accordance with said detected peak levels, wherein when at least one of said peak levels is equal to or larger than a predetermined value, said gain control signal generator generates the gain control signal to control said gain control amplifier so as to set a level of each of the three primary color digital video signals which are generated from said analog/digital converters to a peak value.
Claim 4
Dependent Claim
194 words
A video signal processing circuit comprising: a gain control amplifier which amplifies each of analog three primary color video signals of red, green, and blue indicative of video information by a predetermined gain and in which said gain is controlled by a gain control signal; analog/digital converters for converting said analog three primary color video signals which are generated from said gain control amplifier into digital signals, respectively; inverse gamma correcting circuits for effecting an inverse gamma correction to said three primary color digital video signals, respectively; a peak level detecting circuit for detecting a peak level of each of the analog three primary color video signals which are supplied to said analog/digital converters; and a gain control signal generator for generating said gain control signal in accordance with said detected peak levels, wherein when at least one of said peak levels is equal to or larger than a predetermined value, said gain control signal generator generates the gain control signal to control said gain control amplifier so as to set a level of each of the three primary color digital video signals which are generated from said analog/digital converters to a peak value.
Claim 5
Dependent Claim
52 words
A circuit according to claim 2 , wherein when said peak levels are less than the predetermined value, said gain control signal generator generates the gain control signal such that said gain control amplifier amplifies each of said analog three primary color video signals by a predetermined gain of “1” or more.
Claim 6
Dependent Claim
170 words
A video signal processing circuit comprising: a matrix circuit to which an analog luminance signal and first and second analog color difference signals indicative of video information are supplied and which generates analog three primary color video signals of red, green and blue; analog/digital converters for converting said analog three primary color video signals into digital signals, respectively; inverse gamma correcting circuits for effecting an inverse gamma correction to said three primary color digital video signals, respectively; a peak level detecting circuit for detecting a peak level of each of said analog three primary color video signals; and a level control circuit for controlling a signal level of said analog luminance signal in accordance with said detected peak levels, wherein when at least one of said peak levels is equal to or larger than a predetermined value, said level control circuit performs a control operation to set a level of each of the three primary color digital video signals which are generated from said analog/digital converters to a peak value.
Claim 7
Dependent Claim
170 words
A video signal processing circuit comprising: a matrix circuit to which an analog luminance signal and first and second analog color difference signals indicative of video information are supplied and which generates analog three primary color video signals of red, green and blue; analog/digital converters for converting said analog three primary color video signals into digital signals, respectively; inverse gamma correcting circuits for effecting an inverse gamma correction to said three primary color digital video signals, respectively; a peak level detecting circuit for detecting a peak level of each of said analog three primary color video signals; and a level control circuit for controlling a signal level of said analog luminance signal in accordance with said detected peak levels, wherein when at least one of said peak levels is equal to or larger than a predetermined value, said level control circuit performs a control operation to set a level of each of the three primary color digital video signals which are generated from said analog/digital converters to a peak value.
Claim 8
Dependent Claim
67 words
A circuit according to claim 4 , wherein when said peak levels are less than the predetermined value, said level control circuit performers a control operation in which so that each of said analog three primary color video signals which are supplied to said analog/digital converters is set to a signal level obtained by multiplying said analog luminance signal by a predetermined coefficient of “1” or more.
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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) | 2004-08-06 | 2005-02-05 | 2005-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-08-06 | 2009-02-05 | 2009-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-08-06 | 2013-02-05 | 2013-08-07 | $7700.00 | Window Closed / Lapsed |