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US5539476A
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Color signal processing with luminance signal correction
Assignee: Canon Inc
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Filing: 1995-06-05
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Granted: 1996-07-23
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Expires: 2015-06-05
Abstract
Abstract In an image pick-up apparatus in which three color signals are gamma-converted and selectively used to generate a luminance signal, a color signal processing apparatus subtracts a linear combination of two color differential signals from the luminance signal to correct the brilliance signal.
Inventors
- 👤 Takashi Sasaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 09:50
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/77
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
153 words
A color signal processing apparatus comprising: image pick-up means for producing three color signals by photo-electrically converting image light from an object illuminated through three color filters; gamma conversion means for gamma-converting the color signals produced by said image pick-up means; means for producing two color differential signals based on the gamma-converted color signals; luminance signal generation means for producing a luminance signal to be corrected based on the gamma-converted color signals; and correction means for subtracting the color differential signals from the luminance signal for correction, wherein the luminance signal to be corrected and the color differential signals are digital signals, and wherein said correction means further comprises shift circuits for shifting the digital color differential signals by a predetermined number of bit positions at a time, complement circuits for complementing the outputs of the shift circuits, and an adder for adding the complements and the digital luminance signal to be corrected.
Claim 2
Dependent Claim
153 words
A color signal processing apparatus comprising: image pick-up means for producing three color signals by photo-electrically converting image light from an object illuminated through three color filters; gamma conversion means for gamma-converting the color signals produced by said image pick-up means; means for producing two color differential signals based on the gamma-converted color signals; luminance signal generation means for producing a luminance signal to be corrected based on the gamma-converted color signals; and correction means for subtracting the color differential signals from the luminance signal for correction, wherein the luminance signal to be corrected and the color differential signals are digital signals, and wherein said correction means further comprises shift circuits for shifting the digital color differential signals by a predetermined number of bit positions at a time, complement circuits for complementing the outputs of the shift circuits, and an adder for adding the complements and the digital luminance signal to be corrected.
Claim 3
Dependent Claim
103 words
An image signal processing apparatus comprising: (a) nonlinear conversion means for nonlinearly converting a plurality of color signals; (b) pixel sequential luminance signal forming means for forming a pixel sequential luminance signal by switching pixel by pixel the plurality of color signals nonlinearly converted by said nonlinear conversion means; (c) color difference signal forming means for forming color difference signals from the plurality of color signals nonlinearly converted by said nonlinear conversion means; and (d) correction means for correcting the pixel sequential luminance signal by subtracting the color difference signals formed by said color difference signal means from the pixel sequential luminance signal.
Claim 4
Dependent Claim
103 words
An image signal processing apparatus comprising: (a) nonlinear conversion means for nonlinearly converting a plurality of color signals; (b) pixel sequential luminance signal forming means for forming a pixel sequential luminance signal by switching pixel by pixel the plurality of color signals nonlinearly converted by said nonlinear conversion means; (c) color difference signal forming means for forming color difference signals from the plurality of color signals nonlinearly converted by said nonlinear conversion means; and (d) correction means for correcting the pixel sequential luminance signal by subtracting the color difference signals formed by said color difference signal means from the pixel sequential luminance signal.
Claim 5
Dependent Claim
24 words
An image signal processing apparatus according to claim 2, wherein said nonlinear conversion means applies a gamma conversion to the plurality of color signals.
Claim 6
Dependent Claim
21 words
An image signal processing apparatus according to claim 2, wherein the plurality of color signals include R, G and B signals.
Claim 7
Dependent Claim
22 words
An image signal processing apparatus according to claim 2, wherein the color difference signals include a R-Y signal and a B-Y signal.
Claim 8
Dependent Claim
31 words
An image signal processing apparatus according to claim 2, further comprising a lowband luminance signal forming means for forming a lowband luminance signal by linearly operating the plurality of color signals.
Claim 9
Dependent Claim
29 words
An image signal processing apparatus according to claim 6, wherein the color difference signals include a R-Y signal and a B-Y signal, wherein Y includes the lowband luminance signal.
Claim 10
Dependent Claim
138 words
An image signal processing apparatus comprising: (a) nonlinear conversion means for nonlinearly converting a plurality of color signals; (b) pixel sequential luminance signal forming means for forming a pixel sequential luminance signal by switching pixel by pixel the plurality of color signals nonlinearly converted by said nonlinear conversion means; (c) lowband luminance signal forming means for forming a lowband luminance signal by linearly operating the plurality of color signals nonlinearly converted by said nonlinear conversion means; (d) color difference signal forming means for forming color difference signals from the plurality of color signals nonlinearly converted by said nonlinear conversion means and said lowband luminance signal; and (e) correction means for correcting the pixel sequential luminance signal by operating the color difference signals formed by said color difference signal forming means with respect to the pixel sequential luminance signal.
Claim 11
Dependent Claim
138 words
An image signal processing apparatus comprising: (a) nonlinear conversion means for nonlinearly converting a plurality of color signals; (b) pixel sequential luminance signal forming means for forming a pixel sequential luminance signal by switching pixel by pixel the plurality of color signals nonlinearly converted by said nonlinear conversion means; (c) lowband luminance signal forming means for forming a lowband luminance signal by linearly operating the plurality of color signals nonlinearly converted by said nonlinear conversion means; (d) color difference signal forming means for forming color difference signals from the plurality of color signals nonlinearly converted by said nonlinear conversion means and said lowband luminance signal; and (e) correction means for correcting the pixel sequential luminance signal by operating the color difference signals formed by said color difference signal forming means with respect to the pixel sequential luminance signal.
Claim 12
Dependent Claim
24 words
An image signal processing apparatus according to claim 8, wherein said nonlinear conversion means applies a gamma conversion to the plurality of color signals.
Claim 13
Dependent Claim
21 words
An image signal processing apparatus according to claim 8, wherein the plurality of color signals include R, G and B signals.
Claim 14
Dependent Claim
29 words
An image signal processing apparatus according to claim 8, wherein the color difference signals include a R-Y signal and a B-Y signal, wherein Y includes the lowband luminance signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-07-23 | 2000-01-22 | 2000-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-07-23 | 2004-01-22 | 2004-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-07-23 | 2008-01-22 | 2008-07-23 | $7700.00 | Window Closed / Lapsed |