US2541865A - Process for producing multilayer color negatives containing masking images for colorcorrection purposes - Google Patents

Description

Feb. 13, 1951 J 5. FRIEDMAN 2,541,

PROCESS FOR PRODUCING MULTILAYER COLOR NEGATIVES CONTAINING MASKING IMAGES FOR COLOR CORRECTION PURPOSES Filed Nov. 18, 1947 F G 1 EXPOSED AND COLOR DEVELOPED MULT/LAYER A 4 COLOR FILM NEGATIVE COLOR IMAGES AND N P0 IL NEGATIVE SILVER H 2 5 VER IMAGES I 1. BLEAGHED 2. EXPOSED TOA common/:0 QUANTITY OF WHITE LIGHT B /4 NEGATIVE cow/e m IMAGES AND SILVER 4/ LA TENT SOSgT/VE BROMIDE I I SILVER ALI E IMAGES DEVELOPED IN DEVELOPER CONTAINING POTASSIUM /0D/DE I /4 UNDEVELOPED NEGATIVE GOLOR SILVER HAL/DE IMAGES AND SILVER /2 BROMIDE POSITIVE S/L VER MA SK/NG IMA GES F/XAT/ON D /4 POSITIVE SILVER I [3 MASK/N6 IMAGES NE GA TI l E G OLOR I 2 IMAGES INVENTOR JOSEPH S. FRIEDMAN ATTORNEYS Patented Feb. 13, 1951 PROCESS FOR PRODUCING MULTILAYER COLOR NEGATIVES CONTAINING MASK- ING IMAGES FOR COLOR CORRECTION PURPOSES Joseph S. Friedman, Johnson City, N. Y., assignor to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware Application November 18, 1947, Serial No. 786,810

2 Claims.

This invention relates to color photography, and more particularly to a process of producing multi-layer color ne atives containing masking images in the cyan and magenta layers for color correction purposes.

In the production of color prints from multilayer color negatives, the color negative consists of yellow, magenta, and cyan images in the different layers. The cyan image represents the red, the magenta image the green, and the yellow image the blue record of the original subject. C'olor positive prints or transparencies may be obtained from such color negatives by direct printing onto a multi-layer color positive film or paper, or by making color separation negatives which are used for making the color positive prints. These color negatives do not, as a rule, completely satisfy the spectral requirements for trichromatic color reproduction. For instance, the magenta colored image, formed by the imposition of green light upon the green sensitive layer, records the green densities. This image should transmit the blue and the red primaries, completely. To the extent to which it absorbs blue light, it superimposes a pattern of the green densities uponv the blue, with consequent color falsification. This color falsification makes itself manifest when the color negative is to be printed. That part of the exposure which is due to blue light, and which should form a record only of the image in the yellow layer in the negative, forms a record of the yellow image admixed with the record of the magenta. The image in the blue sensitive part of the copy mamrial is, therefore, very impure, and serious color degradation results.

It ispossible to overcome this defect if procedures are devised to register a pattern of the magenta dye image, equal in intensity to the degree to which the magenta dye absorbs blue light, but opposite in character, with the yellow dye images. In a similar manner the cyan dye image can be corrected for its blue absorption. These masks or modifying images can be yellow in color, as suggested by the prior art, or they can be a neutral gray, composed of dye or silver.

Numerous methods have been proposed for making corrections in these dye images. Generally, these methods are characterized by the fact that the mask is on a separate piece of film, and must be registered with the original by manual or mechanical means. This creates problems of registry arising from the dimensional variations of film as it ages, and problems of definition arising from lack of optical contact between original and mask, Newton rings, etc. It is desirable, therefore, to have the mask integral with the original. To accomplish this, it has been proposed to place an auxiliary emulsion layer within the pack in which themask could be formed. While this gives a desirable result, it introduces complications into the structure and the preparation of the monopack material. Since the masking image is opposite in character to the one that it is desired to modify, emulsions with special properties have to be used.

To eliminate this complication, it was proposed in British Patent 541,266 to utilize the residual silver-halides in the emulsion after the latent image had been processed to a dye image, and to convert the residual halides, after a proper exposure, into a black and white silver mask. The procedure disclosed, to accomplish the formation of a mask, involved the treatment of the film after negative color development in a bleach bath to convert the silver to silver chloride, removal of the silver chloride by treatment with ammonia or ammonium sulfite, exposure of the untouched residual silver bromide to white light, and development in an M. Q. developer that yields a silver image. When processed in this manner, there are formed silver images in each of the layers of the color film. This may be desirable under certain conditions, but for certain purposes the presence of a mask representing an image of the yellow dye pattern is harmful and undesirable. This was recognized by the British patentee and he specifically states in his specifications that the bleach, to be used to efiect a conversion of the silver to silver chloride, be of such a mild nature that it does not destroy the color sensitivities of the green and red sensitive layers. After treatment with such a mild bleach solution, it becomes possible to selectively expose the red and/or green sensitive layers, so that .masking images are formed only in these parts.

The restriction that a bleach be used that is so mild that it does not destroy the color sensitivity of the green and red layers, severely limits the operator using the material and the manufacturer who makes it. The patentee cites a number of sensitizing agents that could be used, which will not be destroyed by the extremely mild agents he mentions. But, generally, subjecting an optically sensitized film to the action of an oxidizing agent reduces the color sensitivity of that material almost to the vanishing point. To

emulsion grain layers. probably difiuses much faster than the potassium iodide.

:de'eper sections of the emulsion layers. all developing action is stopped in the yellow or uppermost layer, but not in the cyan and mageneflect a selective exposure in the green and red sensitive layers would require such long durations as to make the procedure impractical unless special sensitizers be used which are not so affected.

Another method, recently proposed, consists of forming. masking images in the original green and red sensitive layers by a reversal processing. The procedure proposed, to accomplish the formation of a mask, is to color develop the exposed multilayer color film and then subject it to the action of a special fixing bath whose penetration into the depth of the emulsion layer can be controlled and the fixing action thereof limited to the uppermost blue sensitive layer. By this procedure, the residual silver-halides in the blue sensitive layer are removed and can no longer be used to form a masking image, whereas the residual silver-halides in the green and red sensitive layers are substantially unafiected and masking images are formed in these layers upon subsequent exposure and development.

The use of a controlled fixing'bath, whose action is limited only to a green layer, presents a complex problem. For instance, it is extremely difiicult to prepare such a bath which will have no effect whatsoever upon the residual silverhalides in the other two layers, due to the com- -plication of maintaining a sharp line of penetration as the bath solution becomes absorbed or diffuses through the gelatin.

It'is, therefore, an object of the present invention to provide a method for obtaining, in subtractively multi-layer colored photographic color negative materials, masking images composed of silver which correct for the color deficiencies of the cyan and magenta dye images thereof.

A further object is to provide a method for obtaining color corrected color negative materials wherein the color correction is integrally bound with the cyan and magenta dye images. Other objects and advantages of this invention will be apparent by reference to the foregoing specification, in which its preferred details and embodiments are described.

The foregoing objects are accomplished by developing an exposed, color-developed, bleached, "and re-exposed color negative film in the usual black and white developer containing a small quantity of potassium iodide which will govern the depth at which development will start. The potassium iodide does not function as a developer, or fog-inhibiting agent. Its function is to control the extent below the top surface of the emulsion ,layer at which development will start.

During this controlled depth development, the potassium iodide desensitizes the upper strata of the The developing solution Hence, in the deeper sections of the emulsion layers, i. e., the magenta and cyan lay- .ers, the developing solution acts normally as though the potassium iodide were absent, since by the time the development action starts, said potassium iodide will have not penetrated to the In short,

this controlled depth development, there is achieved the formation of color-correcting silver images in the magenta and cyan layers.

4 In practicing the present invention, the process involved comprises the following steps:

1. Exposure of the color negative film.

2. Development of the latent images with a color developer.

3. Short-stopping with an acid bath and washing in running water.

4. Bleaching, i. e., converting, of all the silver negative images and any other silver, such as the colloidal silver that may be present in the yellow filter and anti-halation layers, into silver bromide by any bleach bath which does not impair the dye images already present.

5. Exposure of the film to a controlled quantity of White light.

6. Development of the masking images by means of a black and white developer, containing from 0.02 to 0.4 gram of potassium iodide per liter of developer for a period of time ranging from 2 to 10 minutes.

7. Fixation of the unused silver bromide.

8. Washing and drying in the usual manner.

It is to be noted that, during the bleaching of the exposed and color-developed film, the bleach bath reconverts the negative silver images to silver bromide and these newly formed silver bromide grains are light-sensitive, so that upon reexposure and development with a developing agent containing potassium iodide, the latent images of silver bromide grains form silver images. The sensitivity of the reformed silver bromide grains is very much less than the sensitivity of the residual silver bromide left after cclordevelopment. Hence, ample sensitivity differential exists between the silver bromide formed by the rehalogenation of the negative silver image and the residual silver bromide to allow the formation of latent images only in the residual silver bromide.

It should be pointed out that, although any black and white developer to which potassium iodide has been added may be employed, 1 prefer those developers which contain hydroquinone, or p-aminophenol as the reducing agent, because they have the least effect upon the dye images formed in the three layers.

The foregoing description of my invention will be more apparent from the following example which is set forth merely to illustrate and should not be construed as a limitation thereof.

Example A multi-layer photographic color film, such as prepared according to U. S. Patents 2,179,228; 2,179,239;-2,l86,849; 2,220,187 and 2,357,388, was exposed to a colored object and then developed for 15 minutes in a color developer of the following composition:

portions of the multi-layer film. The color developed film was then short-stopped in a 1% solution of acetic acid containing 1% sodium. acetate, .and washed'for 10 minutes in running water.

.After washing, all of the metallicsilver in all Disodium monopotassium ferricyanide grams 100.0 Potassium bromide do 15.0 Disodium phosphate do 400 Sodium sulfate do 22.5 Water to make liters 1 depth developer of the following composition:

p-Aminophenol grams 5.0 Sodium sulfite do 40.0 Sodium metaborate do 40.0 Potassium bromide do 8.0 Potassium iodide do 0.4 Water to make liters 1 The developed film was then washed, fixed, and dried in the usual manner.

During the masking development, the exposed silver-halides present in the cyan and magenta layers were reduced to metallic silver, thereby forming in each such layer a masking image composed of metallic silver to provide for color correction in printing. No such development took place in the yellow (uppermost) layer.

The procedure of the foregoing example has the advantage over other masking methods in that it cuts down the number of processing steps and reduces the time of processing.

In the accompanying drawing, Figure 1 is a flow diagram representing enlarged sectional views of a film showing the method of forming a masked image according to my invention. Views A, B, and C of Figure 1 illustrate the changes taking place in the film during the various stages of processing.

As shown in the figure, I 0 is a transparent base or support having superposed thereon, layers ll,

l2, and I4 containing cyan, magenta, and yellow color images, respectively. Layer 13 represents a filter layer.

A illustrates a section of the multilayer color .film which has been exposed and color reveloped.

B illustrates the same multilayer color film after it has been bleached and exposed to a controlled quantity of white light. C illustrates the same multilayer color film after it has been developed in a developer containing potassium iodide. D illustrates the'same multilayer color film after fixation.

It will be noted that masking images consisting to those skilled in the art which, however, do not depart from the spirit and nature of this invention and I do not intend to be limited in the patent granted except as required in the follow ing claims.

I claim:

1. In the production of subtractively colored negatives with correction printing masks, integrally bound therein, for multi-layer film comprising an impermeable support having superimposed silver-halide emulsion layers containing color-formers and being respectively sensitized to the blue, green, and red regions of the spectrum, the blue sensitive layer being outermost, by exposing said multi-layer film to a colored object, color developing, whereby yellow, magenta, and cyan images are formed in the respective layers, andrehalogenizing the metallic silver by bleaching and re-exposing, the improvement which comprises exposing all layers of the bleached film to substantially white light to permit the formation of latent images only in the residual silverhalide without the formation of latent images in the silver-halide obtained by bleaching, and developing the re-expo-sed silver-halide layers to positive silver images only in the magenta and cyan layers in a black and white developer containing from 0.02 to 0.4 gram per liter of developer of a depth controlling reagent consisting of potassium iodide.

2. In the production of subtractively colored negatives with correction printing masks, integrally bound therein, for multi-layer film comprising animpermeable support having superimposed silver-haiiole emulsion layers containing color-formers and being respectively sensitized to the blue, green and. red regions of the spectrum, the blue sensitive layer being outermost, by exposing said muiti-layer mm to a colored object, color developing, whereby yellow, magenta, and cyan images are formed in the respective layers, and renalogenizing the metallic silver by bleaching, and re-exposing, the improvement which comprises exposing all layers of the bleached film to substantially white light to perbleaching, and developing the re-exposed silverhalide layers to positive silver images in the magenta and cyan layers in a black and white developer of the following composition:

p-Aminophenol grams 5.0 Sodium sulfite do 40.0 Sodium metaborate do 40.0 Potassium bromide do 8.0 Potassium iodide do 0.4 Water to make liters 1 JOSEPH S. FRIEDMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,137,785 Sanders- Dolgoruki et al. Nov. 22, 1938 2,153,698 Reindorp Apr. 11, 1939 2,159,600 Murray et a1. May 23, 1939 2,203,653 Evans June 4, 1940 2,431,996 Duerr et a1. Dec. 2, 1947

Claims (1)

1. IN THE PRODUCTION OF SUBTRACTIVELY COLORED NEGATIVES WITH CORRECTION PRINTING MASKS, INTEGRALLY BOUND THEREIN, FOR MULTI-LAYER FILM COMPRISING AN IMPERMEABLE SUPPORT HAVING SUPERIMPOSED SILVER-HALIDE EMULSION LAYERS CONTAINING COLOR-FORMERS AND BEING RESPECTIVELY SENSTITIZED TO THE BLUE, GREEN, AND RED REGIONS OF THE SPECTRUM, THE BLUE SENSITIVE LAYER BEING OUTERMOST, BY EXPOSING SAID MULTI-LAYER FILM TO A COLORED OBJECT, COLOR DEVELOPING, WHEREBY YELLOW, MAGENTA, AND CYAN IMAGES ARE FORMED IN THE RESPECTIVE LAYERS, AND REHALOGENIZING THE METALLIC SILVER BY BLEACHING AND RE-EXPOSING, THE IMPROVEMENT WHICH COMPRISES EXPOSING, THE IMPROVEMENT WHICH TO SUBSTANTIALLY WHITE LIGHT TO PERMIT THE FORMATION OF LATENT IMAGES ONLY IN THE RESIDUAL SILVERHALIDE WITHOUT THE FORMATION OF LATENT IMAGES IN THE SILVER-HALIDE OBTAINED BY BLEACHING, AND DEVELOPING THE RE-EXPOSED SILVER-HALIDE LAYERS TO POSITIVE SILVER IMAGES ONLY IN THE MAGNETA AND CYAN LAYERS IN A BLACK AND WHITE DEVELOPER CONTAINING FROM 0.62 TO 0.4 GRAM PER LITER OF DEVELOPER OF A DEPTH CONTROLLING REAGENT CONSISTING OF POTASSIUM IODIDE.

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