US5296920A
Expired / Lapsed
US
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Color gradation correction method and apparatus
Assignee: Panasonic Holdings Corp
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Filing: 1992-09-16
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Granted: 1994-03-22
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Expires: 2012-09-16
Abstract
Abstract A gradation correction apparatus for processing R, G, and B input signals includes a luminance signal conversion device for obtaining the original luminance signal, which is before gamma conversion, from the input signals, a luminance gamma conversion device for gamma converting the original luminance signal to the desired gradation characteristics to obtain a gamma converted luminance signal, a correction coefficient calculation means for obtaining a ratio of the gamma converted luminance signal to the original luminance signal, a first RGB operation means for multiplying the ratio by each of the R, G, and B input signals for obtaining primary gradation-corrected R, G, and B signals; a color difference signal operation means for producing a difference between each of the R, G, and B input signals and the original luminance signal; a second RGB operation means for adding the gamma converted luminance signal to each of the difference for obtaining secondary gradation-corrected R, G, and B signals; and an RGB determination means for obtaining final gradation-corrected R, G, B signals based on the primary and secondary gradation-corrected R, G, and B signals.
Inventors
- 👤 Shigeo Sakaue
- 👤 Susumu Maruno
- 👤 Haruo Yamashita
- 👤 Yasuki Matsumoto
- 👤 Hideshi Ishihara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:04
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/00795; H04N9/00; H04N9/64; H04N9/68; H04N9/69; H04N1/46; H04N1/56; H04N1/60; H04N1/6027; H04N23/00; H04N23/80; H04N23/82; H04N23/83; H04N9/77
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
137 words
A gradation correction method comprising the steps of: (a) obtaining an original luminance signal, which is before gamma conversion, from R, G, and B input signals; (b) gamma converting said original luminance signal according to a predetermined gradation characteristics for obtaining a gamma converted luminance signal; (c) multiplying a ratio of the gamma converted luminance signal to the original luminance signal by each of the R, G, and B input signals for obtaining primary gradation-corrected R, G, and B signals; (d) adding a difference between each of the R, G, and B input signals and the original luminance signal to the gamma converted luminance signal for obtaining secondary gradation-corrected R, G, and B signals; and (e) obtaining a final gradation-corrected R, G, and B signals based on said primary and secondary gradation-corrected R, G, and B signals.
Claim 2
Dependent Claim
137 words
A gradation correction method comprising the steps of: (a) obtaining an original luminance signal, which is before gamma conversion, from R, G, and B input signals; (b) gamma converting said original luminance signal according to a predetermined gradation characteristics for obtaining a gamma converted luminance signal; (c) multiplying a ratio of the gamma converted luminance signal to the original luminance signal by each of the R, G, and B input signals for obtaining primary gradation-corrected R, G, and B signals; (d) adding a difference between each of the R, G, and B input signals and the original luminance signal to the gamma converted luminance signal for obtaining secondary gradation-corrected R, G, and B signals; and (e) obtaining a final gradation-corrected R, G, and B signals based on said primary and secondary gradation-corrected R, G, and B signals.
Claim 3
Dependent Claim
44 words
A gradation correction method as claimed in claim 1, wherein said step (e) obtains the final gradation-corrected R, G, and B signals by interpolation from the primary and secondary gradation-corrected R, G, and B signals depending on the value of the original luminance signal.
Claim 4
Dependent Claim
181 words
A gradation correction apparatus for processing R, G, and B input signals, comprising: a luminance signal conversion means for obtaining the original luminance signal, which is before gamma conversion, from the input signals; a luminance gamma conversion means for gamma converting said original luminance signal to the desired gradation characteristics to obtain a gamma converted luminance signal; a correction coefficient calculation means for obtaining a ratio of the gamma converted luminance signal to the original luminance signal; a first RGB operation means for multiplying said ratio by each of the R, G, and B input signals for obtaining primary gradation-corrected R, G, and B signals; a color difference signal operation means for producing a difference between each of the R, G, and B input signals and the original luminance signal; a second RGB operation means for adding the gamma converted luminance signal to each of said difference for obtaining secondary gradation-corrected R, G, and B signals; and an RGB determination means for obtaining final gradation-corrected R, G, B signals based on said primary and secondary gradation-corrected R, G, and B signals.
Claim 5
Dependent Claim
181 words
A gradation correction apparatus for processing R, G, and B input signals, comprising: a luminance signal conversion means for obtaining the original luminance signal, which is before gamma conversion, from the input signals; a luminance gamma conversion means for gamma converting said original luminance signal to the desired gradation characteristics to obtain a gamma converted luminance signal; a correction coefficient calculation means for obtaining a ratio of the gamma converted luminance signal to the original luminance signal; a first RGB operation means for multiplying said ratio by each of the R, G, and B input signals for obtaining primary gradation-corrected R, G, and B signals; a color difference signal operation means for producing a difference between each of the R, G, and B input signals and the original luminance signal; a second RGB operation means for adding the gamma converted luminance signal to each of said difference for obtaining secondary gradation-corrected R, G, and B signals; and an RGB determination means for obtaining final gradation-corrected R, G, B signals based on said primary and secondary gradation-corrected R, G, and B signals.
Claim 6
Dependent Claim
43 words
A gradation correction apparatus according to claim 3, wherein said RGB determination means obtains the final gradation-corrected R, G, B signals by interpolation from said primary and secondary gradation-corrected R, G, and B signals depending on the value of the original luminance signal.
Claim 7
Dependent Claim
109 words
A gradation correction method comprising the steps of: (a) obtaining an original luminance signal and first and second original color difference signals; (b) gamma converting said original luminance signal according to a predetermined gradation characteristics for obtaining a gamma converted luminance signal; (c) multiplying a ratio of the gamma converted luminance signal to the original luminance signal by each of the first and second original color difference signals for obtaining first and second primary gradation-corrected color difference signals; and (d) obtaining first and second final gradation-corrected color difference signals based on said first and second primary gradation-corrected color difference signals and said first and second original color difference signals.
Claim 8
Dependent Claim
109 words
A gradation correction method comprising the steps of: (a) obtaining an original luminance signal and first and second original color difference signals; (b) gamma converting said original luminance signal according to a predetermined gradation characteristics for obtaining a gamma converted luminance signal; (c) multiplying a ratio of the gamma converted luminance signal to the original luminance signal by each of the first and second original color difference signals for obtaining first and second primary gradation-corrected color difference signals; and (d) obtaining first and second final gradation-corrected color difference signals based on said first and second primary gradation-corrected color difference signals and said first and second original color difference signals.
Claim 9
Dependent Claim
44 words
A gradation correction method as claimed in claim 5, wherein said step (d) obtains the final gradation-corrected color difference signal by interpolation from the primary gradation-corrected color difference signals and said original color difference signals depending on the value of the original luminance signal.
Claim 10
Dependent Claim
86 words
A gradation correction method comprising the steps of: (a) obtaining an original luminance signal and two-phase modulated original chroma signal; (b) gamma converting said original luminance signal according to a predetermined gradation characteristics for obtaining a gamma converted luminance signal; (c) multiplying a ratio of the gamma converted luminance signal to the original luminance signal by said original chroma signal for obtaining a primary gradation-corrected chroma signal; and (d) obtaining final gradation-corrected chroma signal based on said primary gradation-corrected chroma signal and said original chroma signal.
Claim 11
Dependent Claim
86 words
A gradation correction method comprising the steps of: (a) obtaining an original luminance signal and two-phase modulated original chroma signal; (b) gamma converting said original luminance signal according to a predetermined gradation characteristics for obtaining a gamma converted luminance signal; (c) multiplying a ratio of the gamma converted luminance signal to the original luminance signal by said original chroma signal for obtaining a primary gradation-corrected chroma signal; and (d) obtaining final gradation-corrected chroma signal based on said primary gradation-corrected chroma signal and said original chroma signal.
Claim 12
Dependent Claim
41 words
A gradation correction method as claimed in claim 7, wherein said step (d) obtains the final gradation-corrected chroma signal by interpolation from said primary gradation-corrected chroma signal and said original chroma signal depending on the value of the original luminance signal.
Claim 13
Dependent Claim
128 words
A gradation correction apparatus for processing an input luminance signal and first and second input color difference signals comprising: a luminance gamma conversion means for gamma converting said input luminance signal to the desired gradation characteristics to obtain a gamma converted luminance signal; a correction coefficient calculation means for obtaining a ratio of the gamma converted luminance signal to the input luminance signal; a color difference conversion means for multiplying each of said first and second color difference signals by said ratio for obtaining first and second primary gradation-corrected color difference signals and a color difference determination means for obtaining first and second final gradation-corrected color difference signals based on said first and second primary gradation-corrected color difference signals and said first and second input color difference signals.
Claim 14
Dependent Claim
128 words
A gradation correction apparatus for processing an input luminance signal and first and second input color difference signals comprising: a luminance gamma conversion means for gamma converting said input luminance signal to the desired gradation characteristics to obtain a gamma converted luminance signal; a correction coefficient calculation means for obtaining a ratio of the gamma converted luminance signal to the input luminance signal; a color difference conversion means for multiplying each of said first and second color difference signals by said ratio for obtaining first and second primary gradation-corrected color difference signals and a color difference determination means for obtaining first and second final gradation-corrected color difference signals based on said first and second primary gradation-corrected color difference signals and said first and second input color difference signals.
Claim 15
Dependent Claim
51 words
A gradation correction apparatus according to claim 9, wherein said color difference determination means obtains the final gradation-corrected color difference signals by interpolation from said first and second primary gradation-corrected color difference signals and said first and second input color difference signals depending on the value of the input luminance signal.
Claim 16
Dependent Claim
102 words
A gradation correction apparatus for processing an input luminance signal and an input chroma signal comprising: a luminance gamma conversion means for gamma converting said input luminance signal to the desired gradation characteristics to obtain a gamma converted luminance signal; a correction coefficient calculation means for obtaining a ratio of the gamma converted luminance signal to the input luminance signal; a chrominance conversion means for multiplying said input chroma signal with said ratio for obtaining primary gradation-corrected chroma signals; and a chrominance determination means for obtaining final gradation-corrected chroma signal based on said primary gradation-corrected chroma signal and said input chroma signal.
Claim 17
Dependent Claim
102 words
A gradation correction apparatus for processing an input luminance signal and an input chroma signal comprising: a luminance gamma conversion means for gamma converting said input luminance signal to the desired gradation characteristics to obtain a gamma converted luminance signal; a correction coefficient calculation means for obtaining a ratio of the gamma converted luminance signal to the input luminance signal; a chrominance conversion means for multiplying said input chroma signal with said ratio for obtaining primary gradation-corrected chroma signals; and a chrominance determination means for obtaining final gradation-corrected chroma signal based on said primary gradation-corrected chroma signal and said input chroma signal.
Claim 18
Dependent Claim
41 words
A gradation correction apparatus according to claim 11, wherein said chrominance determination means obtains the final gradation-corrected chroma signal by interpolation from said primary gradation-corrected chroma signal and said input chroma signal depending on the value of the input luminance 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) | 1997-03-21 | 1997-09-20 | 1998-03-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-03-21 | 2001-09-20 | 2002-03-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-03-21 | 2005-09-20 | 2006-03-22 | $7700.00 | Window Closed / Lapsed |