US4860103A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Video level control
Assignee: PRINCETON DIGITAL IMAGE Corp
•
Filing: 1988-11-22
•
Granted: 1989-08-22
•
Expires: 2008-11-22
Abstract
Abstract An analog-to-digital converter 2 for video signals has a sensitivity (reference) input 4 controlled by a controller 10 in response to the converter's digital output so as to maintain the grey level with a predetermined range. Preferably the controller employs an irregular subsampling of the digital values, and responds differently to extreme and mid-range samples. A scale factor may be forwarded to a digital-to-analog converter for reconversion.
Inventors
- 👤 Mohammad S. Azam
- 👤 Michael D. Carr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:43
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/12; H03M1/18; H03M1/181; H03M1/183; H03M1/185; H04; H04N; H04N5/00; H04N5/14; H04N5/20
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
98 words
A digital video coder comprising a video input for receiving analogue video signals directly from a camera; an analogue-to-digital converter connected to the input and having an output for providing digital words representing successive samples of the input video signals and a control input for varying the sensitivity of the converter; and control means responsive to the digital words at the output of the converter to generate digitally, as a function of the average amplitude level represented by previous said digital words at the converter output, a control signal for application to the control input of the converter.
Claim 2
Dependent Claim
98 words
A digital video coder comprising a video input for receiving analogue video signals directly from a camera; an analogue-to-digital converter connected to the input and having an output for providing digital words representing successive samples of the input video signals and a control input for varying the sensitivity of the converter; and control means responsive to the digital words at the output of the converter to generate digitally, as a function of the average amplitude level represented by previous said digital words at the converter output, a control signal for application to the control input of the converter.
Claim 3
Dependent Claim
141 words
A digital video coder comprising a video input for receiving analogue video signals from a camera; an analogue-to-digital converter connected to the input and having an output for providing digital words representing successive samples of the input video signals and a control input for varying the sensitivity of the converter; and control means responsive to the digital words at the output of the converter to generate digitally, as a function of the amplitudes represented by the digital words at the converter output, a control signal for application to the control input of the converter, wherein such control means is arranged to subsample the words to select a minority of the words available at the said digital output, the rate of the sampling being irregular, whereby the selected words represent a random selection from the picture area represented by the video signals.
Claim 4
Dependent Claim
141 words
A digital video coder comprising a video input for receiving analogue video signals from a camera; an analogue-to-digital converter connected to the input and having an output for providing digital words representing successive samples of the input video signals and a control input for varying the sensitivity of the converter; and control means responsive to the digital words at the output of the converter to generate digitally, as a function of the amplitudes represented by the digital words at the converter output, a control signal for application to the control input of the converter, wherein such control means is arranged to subsample the words to select a minority of the words available at the said digital output, the rate of the sampling being irregular, whereby the selected words represent a random selection from the picture area represented by the video signals.
Claim 5
Dependent Claim
52 words
An apparatus according to claim 1 in which the control means includes means for sampling selected words and for accumulating a sum of a predetermined number of the selected words and to apply to the said control signal a correction proportional to the difference between the accumulated sum and a reference value.
Claim 6
Dependent Claim
33 words
An apparatus according to claim 3 in which the control means is arranged to apply the correction only if the accumulated sum differs from the reference value by more than a predetermined margin.
Claim 7
Dependent Claim
40 words
An apparatus according to claim 3 or 4 in which the control means is arranged to omit from the sum of any of the selected words whose value is equal to that of a previous one of the selected words.
Claim 8
Dependent Claim
37 words
An apparatus according to claim 3, or 4 in which the control means is arranged to omit from the sum any of the selected words whose value lies above a higher, or below a lower threshold value.
Claim 9
Dependent Claim
81 words
An apparatus according to claim 6 in which the control means is arranged to count the number of the selected words whose values lie respectively above and below the higher and lower threshold values during each accumulation period, and if the number of selected words whose values lie above said higher threshold value or the number of selected words whose value lies below said lower threshold value exceeds a respective predetermined number, to apply a correction to the said control signal.
Claim 10
Independent Claim
33 words
An apparatus according to any one of the preceding claims 1, 2, 3 or 4 including further analogue-to-digital converters, having sensitivity control inputs controlled by the said control signal, for receiving colour-difference signals.
Claim 11
Independent Claim
161 words
An apparatus for video processing, storage or transmission, comprising a processing apparatus having a video input for receiving analogue video signals from a camera; an analogue-to-digital converter connected to the input and having an output for providing digital words representing successive samples of the input video signals and a control input for varying the sensitivity of the converter; and control means responsive to the digital words at the output of the converter to generate digitally, as an function of the amplitudes represented by the digital words at the converter output, a control signal for application to the control input of the converter, and an output digital-to-analogue converter coupled to the output of said analogue-to-digital converter arranged for reconversion of the digital signals, following processing, storage or transmission, to an analogue signal, said control signal being delayed, stored or transmitted and being supplied to the output digital-to-analogue converter to control its sensitivity to correspond to that of the analogue to digital converter.
Claim 12
Independent Claim
161 words
An apparatus for video processing, storage or transmission, comprising a processing apparatus having a video input for receiving analogue video signals from a camera; an analogue-to-digital converter connected to the input and having an output for providing digital words representing successive samples of the input video signals and a control input for varying the sensitivity of the converter; and control means responsive to the digital words at the output of the converter to generate digitally, as an function of the amplitudes represented by the digital words at the converter output, a control signal for application to the control input of the converter, and an output digital-to-analogue converter coupled to the output of said analogue-to-digital converter arranged for reconversion of the digital signals, following processing, storage or transmission, to an analogue signal, said control signal being delayed, stored or transmitted and being supplied to the output digital-to-analogue converter to control its sensitivity to correspond to that of the analogue to digital converter.
Claim 13
Independent Claim
83 words
An apparatus for video processing, storage or transmission comprising a processing video coder apparatus according to claims 1, 2, 3, or 4 and an output digital-to analogue converter coupled to the output of said analogue-to-digital converter arranged for reconversion of the digital signals, following processing, storage or transmission, to an analogue signal, the said control signal being delayed, stored or transmitted and being supplied to the output digital-to-analogue converter to control its sensitivity to correspond to that of the analogue to digital converter.
Claim 14
Dependent Claim
119 words
A digital video coder comprising a video input for receiving analogue video signals directly from a camera; an analogue-to-digital converter connected to the input and having an output for providing digital words representing successive samples of the input video signals and a control input for varying the sensitivity of the converter; and control means responsive to the digital words at the output of the converter to generate digitally, as an arithmetic function of the amplitudes represented by the digital words at the converter output, a control signal for application to the control input of the converter for controlling the average level represented by said digital words by maintaining the average level of said digital words within a predetermined range.
Claim 15
Dependent Claim
119 words
A digital video coder comprising a video input for receiving analogue video signals directly from a camera; an analogue-to-digital converter connected to the input and having an output for providing digital words representing successive samples of the input video signals and a control input for varying the sensitivity of the converter; and control means responsive to the digital words at the output of the converter to generate digitally, as an arithmetic function of the amplitudes represented by the digital words at the converter output, a control signal for application to the control input of the converter for controlling the average level represented by said digital words by maintaining the average level of said digital words within a predetermined range.
References Cited (Backward Citations)
EP0083865A2
Cited
GB2130839A
Cited
US4642694A
Cited
JPS616994A
Cited
US4625240A
Cited
EP0178044A2
Cited
US4628362A
Cited
JPS6281815A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-08-21 | 1993-02-20 | 1993-08-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-08-21 | 1997-02-20 | 1997-08-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-08-21 | 2001-02-20 | 2001-08-22 | $7700.00 | Window Closed / Lapsed |