GB1206424A - Photographic colour printer - Google Patents
Photographic colour printerInfo
- Publication number
- GB1206424A GB1206424A GB33482/67A GB3348267A GB1206424A GB 1206424 A GB1206424 A GB 1206424A GB 33482/67 A GB33482/67 A GB 33482/67A GB 3348267 A GB3348267 A GB 3348267A GB 1206424 A GB1206424 A GB 1206424A
- Authority
- GB
- United Kingdom
- Prior art keywords
- light
- blue
- exposure
- printing
- photo
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000000463 material Substances 0.000 abstract 3
- 239000003990 capacitor Substances 0.000 abstract 2
- 239000003086 colorant Substances 0.000 abstract 1
- 238000006073 displacement reaction Methods 0.000 abstract 1
- 238000000034 method Methods 0.000 abstract 1
- 230000003287 optical effect Effects 0.000 abstract 1
- 238000002834 transmittance Methods 0.000 abstract 1
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B27/00—Photographic printing apparatus
- G03B27/72—Controlling or varying light intensity, spectral composition, or exposure time in photographic printing apparatus
- G03B27/73—Controlling exposure by variation of spectral composition, e.g. multicolor printers
- G03B27/735—Controlling exposure by variation of spectral composition, e.g. multicolor printers in dependence upon automatic analysis of the original
Abstract
1,206,424. Photographic colour printing. ILFORD Ltd. July 12, 1968 [July 20, 1967], No.33482/67. Heading G2A. A method of printing positives from multi-colour negatives comprises continuing printing for each colour component of printing light, red, green and blue, until a predetermined integral of light against time for each colour has been administered to the print material as measured by an exposure control means, the integral being constant for negatives representing subjects integrating to grey, but being reduced for at least two colours in response to means for detecting an abnormally low ratio of integrated transmittance to the negative of blue light relative to light of a longer wavelength. Photocells 8, 9, 10 Fig. 1 sensitive respectively to red, green and blue light are connected to a photoelectric integrator arranged to operate a shutter to terminate exposure of print material 7 to the corresponding colour component of printing light, additional photo-cells 11, 12 being responsive respectively to blue light and a light of longer wavelength, e.g. yellow. A double optical wedge 13 is movable by a motor 19 into the path of printing light and out of the path of reflected light incident on photo-cell 11, or vice versa. Photo-cells 11, 12 are connected in to form two arms of a bridge circuit, Fig.2, (not shown), two resistors (17), (18) one being adjustable, forming the other arms. The junction of the photo-cells is connected to one input of a differential amplifier (16), the other input being connected to the junction between the resistors. The output of the ampliflier is connected to the motor 19. An alternative embodiment of the invention is shown in Fig.4. Photo-multiplier tubes 24, 25, 26 sensitive respectively to blue, green and red light provide currents proportional to the respective light intensities to charge capacitors 36, 37, 38 until valves 39, 40, 41 conduct whereupon the exposure of the print material to the corresponding colour is terminated by a shutter. Upon commencement of an exposure cycle switches 33, 34, 35, 44, 45, 46 open. The relative intensities of the blue, green and red printing light are arranged so that equal exposure times of these components produce satisfactory prints of negatives representing subjects integrating to grey. The retardation of the rise in voltage of capacitors 37, 38 due to i 30 remains at a constant value when a negative being printed represents a subject integrating to grey or yellow. However, when the negative represents subjects integrating to blue, i 30 will be small and will result in the green and red printing exposures terminating at abnormally small exposure integrals, and the blue exposure proceeding to the normal value and thus giving a print that will appear too yellow. This fault is eliminated by not permitting exposure to blue light once both green and red exposures have terminated, e.g. by mechanical or electrical inter-connection of the exposure controlling shutters. In a third embodiment, Fig.5 (not shown) a printer of known type has filter elements (52), yellow, (53), very pale magenta, and (54), blue, are mounted side by side upon a wire which is movable by a motor to selectively position a part of the filter system in the printing light beam. A variable alternator (62) is coupled to the wire and positioned in front of a photo-cell (61) receiving scattered light from the negative (58) to control the exposure time, the variable attenuator being so arranged that upon displacement of the filters to adjust the printing light colour the attenuator moves in front of the photo-cell and allows a greater amount of light to strike the photo-cell when a negative representing a blue subject is being printed thus reducing the exposure time compared with a negative representing a subject integrating to grey or yellow.
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB33482/67A GB1206424A (en) | 1967-07-20 | 1967-07-20 | Photographic colour printer |
US744959A US3591375A (en) | 1967-07-20 | 1968-07-15 | Method of printing positives from color negatives whose subjects integrate to blue |
DE19681772885 DE1772885C3 (en) | 1967-07-20 | 1968-07-17 | Method and apparatus for making photographic color copies |
FR1573675D FR1573675A (en) | 1967-07-20 | 1968-07-19 | |
CH1082368A CH519732A (en) | 1967-07-20 | 1968-07-19 | Method and apparatus for producing positive color images |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB33482/67A GB1206424A (en) | 1967-07-20 | 1967-07-20 | Photographic colour printer |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1206424A true GB1206424A (en) | 1970-09-23 |
Family
ID=10353539
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB33482/67A Expired GB1206424A (en) | 1967-07-20 | 1967-07-20 | Photographic colour printer |
Country Status (4)
Country | Link |
---|---|
US (1) | US3591375A (en) |
CH (1) | CH519732A (en) |
FR (1) | FR1573675A (en) |
GB (1) | GB1206424A (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
IT976489B (en) * | 1973-01-26 | 1974-08-20 | Durst Ag | PROCEDURE AND DEVICE FOR UNDERCORRECTION IN MACHINES PROCEDURE AND DEVICE FOR UNDERCORRECTION IN MACHINES COPYING MACHINES FOR COLOR PHOTOGRAPHIC NEGATIVES INE COPYING FOR COLOR PHOTOGRAPHIC NEGATIVES |
US4168121A (en) * | 1978-04-17 | 1979-09-18 | Pako Corporation | Automatic snow/beach correction for photographic printer |
US4168120A (en) * | 1978-04-17 | 1979-09-18 | Pako Corporation | Automatic exposure corrections for photographic printer |
JPS54139570A (en) * | 1978-04-20 | 1979-10-30 | Matsushita Electric Ind Co Ltd | Image converting and projecting method and apparatus |
-
1967
- 1967-07-20 GB GB33482/67A patent/GB1206424A/en not_active Expired
-
1968
- 1968-07-15 US US744959A patent/US3591375A/en not_active Expired - Lifetime
- 1968-07-19 FR FR1573675D patent/FR1573675A/fr not_active Expired
- 1968-07-19 CH CH1082368A patent/CH519732A/en not_active IP Right Cessation
Also Published As
Publication number | Publication date |
---|---|
DE1772885B2 (en) | 1976-10-21 |
FR1573675A (en) | 1969-07-04 |
DE1772885A1 (en) | 1971-06-16 |
US3591375A (en) | 1971-07-06 |
CH519732A (en) | 1972-02-29 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PS | Patent sealed [section 19, patents act 1949] | ||
PCNP | Patent ceased through non-payment of renewal fee |