Patent US5075778A successfully refreshed from Google Patents.
US5075778A
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US
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Backlight correction system
Assignee: Fujifilm Corp
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Filing: 1990-11-13
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Granted: 1991-12-24
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Expires: 2010-11-13
Abstract
Abstract A television camera with automatic lens opening control provides pictures from backlighted scenes which neither overly darken the subject nor overly brighten the background. The lens opening is controlled by the average value of the incident light intensity, but not before the incident light intensity is subjected to a white compression process. The signal corresponding to the incident light is processed by a white compression circuit to compress the brighter portions of the signal. The compressed output is averaged and used to control the lens opening.
Inventors
- 👤 Kenji Saito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:30
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/70; H04N23/75; H04N23/76
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
105 words
In a television camera of the type comprising an auto-iris system and a process amplifier system providing a camera output signal, said auto-iris system comprising and adjustable iris-stop, a lens, means for developing a video signal corresponding to the incident light intensity, and feedback means for adjusting the iris stop in accordance with an average video signal level, the improvement characterized by a backlight correction circuit, having a nonlinear response as a function of the instantaneous video signal level prior to saturation, for selectively compressing the bright portion of said developed video signal prior to connection to said feedback means and said process amplifier system.
Claim 2
Dependent Claim
105 words
In a television camera of the type comprising an auto-iris system and a process amplifier system providing a camera output signal, said auto-iris system comprising and adjustable iris-stop, a lens, means for developing a video signal corresponding to the incident light intensity, and feedback means for adjusting the iris stop in accordance with an average video signal level, the improvement characterized by a backlight correction circuit, having a nonlinear response as a function of the instantaneous video signal level prior to saturation, for selectively compressing the bright portion of said developed video signal prior to connection to said feedback means and said process amplifier system.
Claim 3
Dependent Claim
38 words
The invention of claim 1 wherein said backlight correction system comprises a white compression circuit for compressing the portion of said video signal exceeding a predetermined level, said white compression circuit being connected to receive said video signal.
Claim 4
Dependent Claim
126 words
A television camera for receiving incident light images comprising an auto iris system, said system comprising: an adjustable iris-stop for limiting said received incident light, a lens for focusing said limited light, a photographing means for converting said limited incident light intensity passing through said lens into a video signal representing said incident light intensity, a white compression circuit, having nonlinear response as a function of the instantaneous video signal level prior to saturation, for selectively compressing those portions of said video signal above a first predetermined level, said circuit providing a first output video signal corresponding to said video signal except that the portions above said first predetermined level are compressed, and means responsive to said first output video signal for adjusting said iris stop.
Claim 5
Dependent Claim
126 words
A television camera for receiving incident light images comprising an auto iris system, said system comprising: an adjustable iris-stop for limiting said received incident light, a lens for focusing said limited light, a photographing means for converting said limited incident light intensity passing through said lens into a video signal representing said incident light intensity, a white compression circuit, having nonlinear response as a function of the instantaneous video signal level prior to saturation, for selectively compressing those portions of said video signal above a first predetermined level, said circuit providing a first output video signal corresponding to said video signal except that the portions above said first predetermined level are compressed, and means responsive to said first output video signal for adjusting said iris stop.
Claim 6
Dependent Claim
28 words
The camera of claim 1 wherein said process amplifier system further comprises at least one of a gamma correction circuit, a white compression circuit and white clipping circuit.
Claim 7
Dependent Claim
30 words
The camera of claim 2 further comprising a process amplifier means for receiving said first output video signal and for further processing said signal to produce a camera output signal.
Claim 8
Dependent Claim
24 words
The camera of claim 5 wherein said process amplifier means comprises means for compressing said first output video signal above a second predetermined level.
Claim 9
Dependent Claim
25 words
The camera of claim 6 wherein said process amplifier means further comprises means for clipping said first output video signal above a third predetermined level.
References Cited (Backward Citations)
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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) | 1994-12-23 | 1995-06-24 | 1995-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-12-23 | 1999-06-24 | 1999-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-12-23 | 2003-06-24 | 2003-12-24 | $7700.00 | Window Closed / Lapsed |