Method and apparatus for producing modified photographic prints

• US 4,933,754 A
• Filed: 06/20/1989
• Issued: 06/12/1990
• Est. Priority Date: 11/03/1987
• Status: Expired due to Fees

• Current Assignee: UBS Ag
• Original Assignee: Ciba-Geigy Corporation (Novartis Ag)
• Inventors: Reed, William G., Maginness, Maxwell G.
• Primary Examiner(s): Britton, Howard W.
• Assistant Examiner(s): Powell, Mark R.
• Application Number:
  US07/371,657
• Time in Patent Office: 357 Days
• Field of Search: 358/80, 358/75, 358/280, 358/302, 358/296, 355/326, 355/327, 355/328, 355/245, 355/228, 355/40
• US Class Current: 358/506
• CPC Class Codes: G03B 27/725 Optical projection devices wherein the contrast is controlled electrically (e.g. cathode ray tube masking)

Abstract

A system for adjusting the density or contrast of a photographic print includes a projection lens system (18) for projecting an image from a negative (10) onto photosensitive paper (20). A matrix array (24) of liquid crystal display elements is interposed in the optical path in front of the print paper (20) and transmissivity of the individual LCD elements is controlled to provide an LCD mask to control the intensity and/or color of the light falling upon the print paper (20). Preferably, a television camera (16) is used with a beam splitter (14) to provide a real-time image of either the LCD mask (24) or the combined image of the mask (24) and negative (10) to allow adjustments in the mask (24) to be viewed as they are made. In printing black and white photos on multicontrast paper, the color transmissivity of the LCD elements is adjusted on an element-by-element basis to provide a localized adjustment of the contrast range of the print paper. Density and contrast can be simultaneously adjusted by controlling both the color balance and overall transmissivity of the LCD elements.

Claims

1. In a photographic projection printer having a light source and a means for holding a film negative in the optical path of said light source to form an image from the negative on a photosensitive element also mounted in said printer, the improvement comprising:

a video camera positioned to view the image produced by the film negative and to produce a video signal representative of that image;

processor means coupled to said video camera for digitizing the video signal and storing the video signal in a matrix array;

control means coupled to said processor means and operable to selectively modify elements of said matrix array; and

a matrix array of liquid crystal display elements interposed between the light source and said negative and coupled to said processor to receive said digitized video signal.

2. The system of claim 1, wherein said liquid crystal display matrix is a black and white transmissive television screen.

3. The system of claim 1, wherein said control means includes manual input means coupled to said processor for operation by an operator to manually modify the elements of said matrix array.

4. The system of claim 1, wherein said digitizing means and control means comprise a digital computer programmed to selectively modify the elements of said matrix array in accordance with a predetermined algorithm.

5. The system of claim 1, wherein said LCD matrix array is a color-transmissive television screen.

6. The system of claim 1, further including a beam splitter mounted between said negative and said photosensitive element to split the image from said negative into a first optical path and a second optical path, said video camera being in the first optical path and said photosensitive element being in the second optical path.

7. The system of claim 1, further including vibrating means connected to said matrix array operable to reciprocate said matrix array transversely to said optical path.

8. The system of claim 6, wherein said beam splitter is a red/infrared beam splitter.

9. The system of claim 1, wherein said video camera includes a pinhole lens in conjunction with the conventional lens.

10. The system of claim 5, further including an optical calibration means connectable to said processor means and said control means for providing reference signals to said processor means to adjust color ratios.

11. The system of claim 5, further including a set of known value optical filters selectively placeable in the path of the video camera for calibrating the color balance and intensity of the exposure of the printer.

12. A method for locally varying the contrast of a multiple-contrast photosensitive paper whose contrast range is dependent upon the color of light striking the photosensitive paper comprising the steps of:

interposing a matrix array of liquid crystal display elements in the optical path of the printer; and

varying the color transmissivity of the matrix array element by element.

13. The method of claim 12, further including the step of locally varying the density of a photographic print by varying the overall light transmissivity of the matrix array element by element.

14. The method of claim 12, further including the step of physically reciprocating the matrix array in the plane of the array so as to minimize the visibility of any structural features of the array in the print.

15. An apparatus for locally varying the contrast of a multiple-contrast photosensitive paper whose contrast range is dependent upon the color of light striking the photosensitive paper comprising:

a holder for holding the photosensitive paper;

a light source;

means for mounting a negative in the path of light from the light source;

a lens system positioned to project an image from said negative on said paper;

a matrix array of liquid crystal display elements positioned in the optical path from said light source to said paper; and

control means connected to said matrix for varying the color transmissivity of said liquid crystal display elements on an element-by-element basis.

17. The apparatus of claim 15, wherein said matrix array is adjacent said paper and of a size substantially the same as the print to be produced.

16. The apparatus of claim 16, further including means for reciprocating said matrix in a plane transverse to said optical path.