US3634611A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Catchlight control in image reproduction systems
Assignee: Crosfield Electronics Ltd
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Filing: 1969-11-12
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Granted: 1972-01-11
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Expires: 1989-11-12
Abstract
Abstract To reproduce colored images, color component signals generated by scanning an original are color corrected and then tone corrected and used to control the exposure of a sensitive surface. ''''Catchlights'''' are reproduced on an extended and nonlinear portion of the tone correction characteristic. To prevent the reproduction on this portion of the characteristic of signals which do not correspond to catchlights but which, through overcorrection in the color correction circuits, have a similar signal level, a catchlight detector circuit is connected in parallel with the color correction circuit so as to receive uncorrected color component signals and to modify the response of the tone correction circuit to a signal from the color correction circuit in the presence of a catchlight signal from the catchlight detector.
Inventors
- 👤 Peter C Pugsley
- 👤 Mouayed Edouard Dobouney
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:25
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/46; H04N1/56; H04N1/60; H04N1/6027
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
181 words
Apparatus for preparing color printers for use in reproducing colored originals, including scanning means for scanning an original to be reproduced, element by element, and generating individual electric signals varying with the densities of different color components of the successively scanned elements of the originals; a color correction circuit connected to receive the uncorrected color signals from the scanner and a tone correction circuit connected to receive color corrected signals from the color correction circuit and to provide tone corrected signals for application to an exposing scanner for exposing a sensitized surface; a catchlight detector circuit connected in parallel with the color correction circuit to receive at its input uncorrected color signals from at least one of the color component channels and generating an output signal only when its input signal level indicates that a catchlight has been scanned; the tone correction circuit including a catchlight control means connected to receive the said output signal, for modifying the response of the tone correction circuit to a color corrected signal from the color correction circuit in the presence of said output signal.
Claim 2
Dependent Claim
181 words
Apparatus for preparing color printers for use in reproducing colored originals, including scanning means for scanning an original to be reproduced, element by element, and generating individual electric signals varying with the densities of different color components of the successively scanned elements of the originals; a color correction circuit connected to receive the uncorrected color signals from the scanner and a tone correction circuit connected to receive color corrected signals from the color correction circuit and to provide tone corrected signals for application to an exposing scanner for exposing a sensitized surface; a catchlight detector circuit connected in parallel with the color correction circuit to receive at its input uncorrected color signals from at least one of the color component channels and generating an output signal only when its input signal level indicates that a catchlight has been scanned; the tone correction circuit including a catchlight control means connected to receive the said output signal, for modifying the response of the tone correction circuit to a color corrected signal from the color correction circuit in the presence of said output signal.
Claim 3
Dependent Claim
45 words
Apparatus in accordance with claim 1, in which the catchlight detector circuit is connected to receive uncorrected color signals from all the color channels and generates a catchlight output signal only when a weighted mean of the uncorrected color signals exceeds a predetermined reference value.
Claim 4
Dependent Claim
61 words
Apparatus in accordance with claim 1, including a catchlight slope control circuit comprising a manually adjustable control, a fixed resistor connected in circuit in an intermediate position of the control and resistive means effective in the positions on opposite sides of the central position for increasing or decreasing the effective resistance in circuit and thereby the slope of the catchlight characteristic.
Claim 5
Dependent Claim
17 words
Apparatus in accordance with claim 3, in which the fixed resistor is mounted on a plug-in carrier.
Claim 6
Dependent Claim
82 words
Apparatus in accordance with claim 3, in which said manually adjustable control includes a switch contact in said central position and switch contacts on opposite sides of said central position, and in which said resistive means on one side of said central position of said control is connected in series with said fixed resistor and the corresponding switch contact and said resistive means on the other side of said central position of said control is connected in parallel with said fixed resistor.
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) | 1975-01-10 | 1975-07-12 | 1976-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-10 | 1979-07-12 | 1980-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-10 | 1983-07-12 | 1984-01-11 | $7700.00 | Window Closed / Lapsed |