US5343302A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Video camera with improved shading correction using clipped parabolic wave signal
Assignee: Sony Corp
•
Filing: 1992-11-09
•
Granted: 1994-08-30
•
Expires: 2012-11-09
Abstract
Abstract A video camera includes a shading correction circuit in which a parabolic wave signal is generated and the level thereof is adjusted in accordance with zoom and iris settings of the camera's optical system. After adjustment, the parabolic wave signal is clipped in accordance with a reference level and the clipped parabolic wave signal is used for correcting the shading of the camera's image signal. The clipping of the parabolic correction signal allows for more accurate shading correction.
Inventors
- 👤 Masahiro Yamashita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 21:15
CPC Classifications
H; H04; H04N; H04N25/00; H04N25/60; H04N25/61; H04N23/00; H04N23/80; H04N23/84; H04N23/86
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
109 words
A video camera including an optical system having a variable optical characteristic, image pickup means receiving light incident thereon from said optical system for generating an image signal, and a shading correction circuit comprising: means for generating a parabolic wave signal; means for adjusting a level of said parabolic wave signal in accordance with said optical characteristic of said optical system, and for outputting an adjusted parabolic wave signal; limiting means for clipping said adjusted parabolic wave signal in accordance with a predetermined reference level to form a correction signal; and means for receiving said correction signal and for correcting said image signal in accordance with said correction signal.
Claim 2
Dependent Claim
109 words
A video camera including an optical system having a variable optical characteristic, image pickup means receiving light incident thereon from said optical system for generating an image signal, and a shading correction circuit comprising: means for generating a parabolic wave signal; means for adjusting a level of said parabolic wave signal in accordance with said optical characteristic of said optical system, and for outputting an adjusted parabolic wave signal; limiting means for clipping said adjusted parabolic wave signal in accordance with a predetermined reference level to form a correction signal; and means for receiving said correction signal and for correcting said image signal in accordance with said correction signal.
Claim 3
Dependent Claim
15 words
A video camera according to claim 1; wherein said limiting means comprises a limiter circuit.
Claim 4
Dependent Claim
15 words
A video camera according to claim 1; wherein said limiting means comprises a compression circuit.
Claim 5
Dependent Claim
21 words
A video camera according to claim 1; wherein said variable optical characteristic corresponds to a zoom position of said optical system.
Claim 6
Dependent Claim
21 words
A video camera according to claim 1; wherein said variable optical characteristic corresponds to an iris parameter of said optical system.
Claim 7
Dependent Claim
192 words
A video camera including an optical system having a variable optical characteristic, image pickup means receiving light incident thereon from said optical system for generating red, green and blue image signals, and a shading correction circuit comprising: means for generating a parabolic wave signal; mixer means including a first manual adjustment means for adjusting a level of said parabolic wave signal in accordance with said optical characteristic of said optical system and in accordance with a setting of said first manual adjustment means, said mixer means outputting an adjusted parabolic wave signal; reference means for providing a predetermined reference level; limiting means for receiving said adjusted parabolic wave signal and said predetermined reference level and clipping said adjusted parabolic wave signal in accordance with said predetermined reference level to form a correction signal; second, third and fourth manual adjustment means for receiving said correction signal and for outputting respective adjusted correction signals; and first, second and third multiplying means for respectively receiving the adjusted correction signals output by said second, third and fourth manual adjustment means and for respectively multiplying said red, green and blue image signals by said adjusted correction signals.
Claim 8
Dependent Claim
192 words
A video camera including an optical system having a variable optical characteristic, image pickup means receiving light incident thereon from said optical system for generating red, green and blue image signals, and a shading correction circuit comprising: means for generating a parabolic wave signal; mixer means including a first manual adjustment means for adjusting a level of said parabolic wave signal in accordance with said optical characteristic of said optical system and in accordance with a setting of said first manual adjustment means, said mixer means outputting an adjusted parabolic wave signal; reference means for providing a predetermined reference level; limiting means for receiving said adjusted parabolic wave signal and said predetermined reference level and clipping said adjusted parabolic wave signal in accordance with said predetermined reference level to form a correction signal; second, third and fourth manual adjustment means for receiving said correction signal and for outputting respective adjusted correction signals; and first, second and third multiplying means for respectively receiving the adjusted correction signals output by said second, third and fourth manual adjustment means and for respectively multiplying said red, green and blue image signals by said adjusted correction signals.
Claim 9
Dependent Claim
219 words
A video camera including an optical system having a variable optical characteristic, image pickup means receiving light incident thereon from said optical system for generating red, green and blue image signals, and a shading correction circuit comprising: means for generating a parabolic wave signal; mixer means, including a first manual adjustment means, for adjusting a level of said parabolic wave signal in accordance with said optical characteristic of said optical system and in accordance with a setting of said first manual adjustment means, said mixer means outputting an adjusted parabolic wave signal; reference means for providing a predetermined reference level; limiting means for receiving said adjusted parabolic wave signal and said predetermined reference level and clipping said adjusted parabolic wave signal in accordance with said predetermined reference level to form a correction signal; switch means for receiving said predetermined reference level and said correction signal and for selectively outputting one of said predetermined reference level and said correction signal; second, third and fourth manual adjustment means for receiving said signal output by said switch means and for outputting respective adjusted signals; and first, second and third multiplying means for respectively receiving the adjusted signals output by said second, third and fourth manual adjustment means and for respectively multiplying said red, green and blue image signals by said adjusted signals.
Claim 10
Dependent Claim
219 words
A video camera including an optical system having a variable optical characteristic, image pickup means receiving light incident thereon from said optical system for generating red, green and blue image signals, and a shading correction circuit comprising: means for generating a parabolic wave signal; mixer means, including a first manual adjustment means, for adjusting a level of said parabolic wave signal in accordance with said optical characteristic of said optical system and in accordance with a setting of said first manual adjustment means, said mixer means outputting an adjusted parabolic wave signal; reference means for providing a predetermined reference level; limiting means for receiving said adjusted parabolic wave signal and said predetermined reference level and clipping said adjusted parabolic wave signal in accordance with said predetermined reference level to form a correction signal; switch means for receiving said predetermined reference level and said correction signal and for selectively outputting one of said predetermined reference level and said correction signal; second, third and fourth manual adjustment means for receiving said signal output by said switch means and for outputting respective adjusted signals; and first, second and third multiplying means for respectively receiving the adjusted signals output by said second, third and fourth manual adjustment means and for respectively multiplying said red, green and blue image signals by said adjusted signals.
Claim 11
Dependent Claim
15 words
A video camera according to claim 7; wherein said switch means is a manual switch.
References Cited (Backward Citations)
US3588338A
Cited
DE2745102A1
Cited
JPS5566178A
Cited
US4562459A
Cited
JPS61105974A
Cited
US4618892A
Cited
US4731652A
Cited
JPS6486064A
Cited
JPH0326071A
Cited
JPH03222586A
Cited
US5157497A
Cited
US5202762A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-08-29 | 1998-02-28 | 1998-08-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-08-29 | 2002-02-28 | 2002-08-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-08-29 | 2006-02-28 | 2006-08-30 | $7700.00 | Window Closed / Lapsed |