US2317369A - Printing process for color photography - Google Patents

Description

April 27, 1943. A A 2,317,369

PRINTING PROCESS FOR COLOR PHOTOGRAPHY Filed D60. 4, 1940 E xxxx"xxx Bela G/wyvar,

Patented Apr. 27 1943' PRINTING PROCESS FOR COLOR PHOTOGRAPHY Bla Gaspar, Hollywood, Calif.,

assignor to Chromogen, Incorporated, a corporation Nevada Application December 4, 1940, Serial No. 368,549

7 Claims This invention relates to photographic printing methods and more particularly to a method for printing silver part images that may be transposed into dlfierently colored part images of substantially equal gradation. This application is a continuation-in-part of my application Serial Number 314,875, filed January 20, 1940, for Printing process for color photography.

It is customary to produce multicolor pictures in a multilayer material by printing the color selection part images of the photographed object into the individual layers of the material to thereby produce silver images which may be employed to obtain colored part images. The resulting colored part images, when combined,

form a subtractive multicolor picture. In order that the color reproduction of the object may be satisfactory, it is necessary that the color gradation of the individual colored part images, which together form the subtractive multicolor picture, be substantially balanced. In other words, those areas at which all dyes are present in maximum concentration should appear black in superposition, and those areas at which all dyes are present in the same fraction of their respectivemaximum concentrations should show a neutral grey in superposition.

, The difierent nature of the dyes employed in forming the color part images frequently cause a difference in their behaviour during the process of producing the color part images in the layers of the multilayer printing material. Accordingly, it has been found possible to obtain color part images of substantially balanced color gradations only when the gradations of the corresponding silver images vary with respect to each other. One method of producing silver images of difierent gradation in the printing material consists in developing the original negatives to difierent gamma-values, for instance, as described in Vertifientlichungen des wissenschaftlichen Zentral-Laboratoriums der photographischen Abteilung-AGFA, Leipzig 1933, vol. III, page 230. Another possibility resides in making black-andwhite intermediate prints of the negative originally obtained, the gradations of these intermediate prints being adjusted to the special characteristics of the different layers of the printing material.

In certain cases, and with materials having certain characteristics, it is difficult to obtain 4 negatives that are developed to adequate gamma printing from separate part images, and instead, to use a multicolor master image, each one of the constituent colored part images of which absorbs those light rays corresponding to the spectral sensitivity of the layer in the multilayer printing material to be employed. Printing into a multilayer printing material from a multicolored master image, however, often involves other difficulties. For instance, theconstituent part images of the multicolor master image. when printed in the usual manner, will not resuit in the production of silver images that possess the gradation requisite for the production of correctly color-balanced prints. This difficulty is particularly apparent if the master image is produced direct from the light-sensitive material which was exposed in the camera. It is likewise encountered when a multi-colored master image is sent to a printing laboratory which is not equipped to properly control or influence its coloration.

Accordingly, it is therefore an object of the present invention to obviate the hereinbefore described difficulties by the provision of a method that will invariably obtain the desired and correct results. Likewise, the invention may be I practiced without the requirement of expensive or delicate equipment, nor is a highly specialized or complicated technique required.

sive-and virtually foolproof method of obtaining first, the desired unequal gradation of the requisite silver part images, and, second, the necessary equal color gradation of the final color part images.

The invention is of primary importance in the production of photographic multicolor pictures by a process wherein the silver images representing different color selections are produced in the different layers of a multilayer material and thereafter treated in a bath which acts to form dye images from said silver images. The silver images produced are of the desired unequal gradation so that the dye image's resulting therefrom are of essentially equal color gradation. These silver images of unequal gradation may be obtained in the multilayer printing material by a printing process in which a multicolor printing matrix, or master image, is used. The individual color selection part images forming the matrix or master image may preferably be in the form of dye images, the color of each of which is such that it absorbs the light acting on the spectrally selectively sensitive emulsion layer Further-' I more, the invention provides a simple, inexpenthat is to receive the color selection record in question.

According to the invention, the required unequal gradations of the silverimages in the printing materials are obtained by printing the differend part images of the master image with colored light of sucha nature that the products of the color gradations of said part -images, when measured in their respective printing lights. and the gamma or contrast .offthe' corresponding emu}:

sion layer in'the printing material or asm-sedto such lights. are in the: same ratio with respect I to each other as'a re the gradations of the individual silver images requisite in the printing materialv for the production of-dye. images of substantially the same gradation. 1

The invention, both as to various embodiments whenread in connection with the accompanying drawing, wherein thesinw cent to the support is sensitized Ior'redlight,

To obtain a satisfactory two-color-picturev by the coloring process to which the developed film is to be subject, a silver image of -y=1.5 is necessary in the outer layer and of :08 in the inner layer. l

The color-sensitive silver halide layers difler in that it they were exposed under a black-andwhite printing matrix and developed in the same manner, the blue light would produce an image oi q-'-=0.9 in the outer layer, whilst the red light wouldproduce an image of 'y=1.1 in the inner layer.

The printing matrix employed for printing the material is a two-colored master image comprising the color selection, for instance, a yellow colored part image, to be printed into the outer layer of ,the printing material and the color selection, such as a blue-green. or blue colored part image, to be printed into the inner layer. A suitable yellow" dye image for the masterimag'e may be formed by the dye chrysophenineG (Schultz Farbstofltabellen, Leipzig 1931, vol. 1, 1th ed., No. 726) which is used in such a' concentration that at the points oi'highest color intensity the concentration oi the dye is 0.8 gm. per sq. m. A suitable blue-green dye image for the master image may be formed by the dye Pontamine Sky Blue 6 BX (Schultz loc. cit., No. 510) which is used in such a concentration that'at the points of highest color intensity'the concentration of the dye is 0.5 gm. per sq. m. whereas the lowest concentration of the dye is zero in both theyellow and the blue-green part images. -Dyeimagesoi this character canbe produced, ior example, from silver images uniformly dyed with the dyes. mentioned above in the concentrations given, and thereafter totally destroying the dye atthe points of the maximum silver deposit.

i p sa ona d method of operation, together. with additional objects and advantages thereof. will be understood from the following description or the 1 aamaee 7 matrix is chosen so that the gradation of the.

{or the yellow par fimagein'the' gn usea for; its printing. "'I'hejchange in the color gradations oi the printing matrix attained by changing the spectral composition of the printing light or; by

employing monochromatic'light ofzadefinite. wave length. It will lie-understoodthat the above stated ratio isspeciilc to the present example only, and that the; exact ratio will vary according to the circumstances; i I I v Another example oi-the invention is bestillustrated" by the accompanying drawing. In order to simplify thedescription, a two-colored master a image such as that hereinbeioredisclosedmay be employed, andto permit easier comprehension oi the invention, hypothetical values may be used.

It will be understood, of course, that three-color 7 master, images and printing materials having three light sensitive silver halide emulsion layers may be used in exactly the same'manner as herein described. In the diagrammatic figure, the

section A illustrates the spectral composition'of comprise a silverhalide light sensitive emulsion layer E, a second silver halide light sensitive emulsion layer F and a supporting layer G. i

The emulsion layer E may be blue sensitive and dyed with a magenta. dye. such as Tuchechtbrillantrot 2B which is referred to in Schultz Farbstofftabellemheipzig, 1932, 7th edition, vol. 2.. page 221. The emulsion layer F may be red sensitive and dyed with a yellow dye such as Xylene-" walkgelb G, referred to in Schultz Farbstofl- -tabellen l. 0., page 232. The blue sensitive emulsion E may be colored with the magenta dyestuil'v in a concentration oi":-1;2 per sq. 'm'i 'and the red sensitive emulsion ll mayzbe colored with the 3 yellowrbestui! in-a concentration of about 1.8

grams per sq. m. The'lemulsion layer Fis'preferably made red sensitiveby -.a red sensitizersuch as Pinacyanol butof course an ordinary panchromatic emulsion maybeused'as the yellow and magenta dyes in the emulsions will exclude blue and green light. a

It is of course desirable to print the record-from the yellow color part image B into the blue' sensitive emulsion E and in print the-record fromxthe black-and-whiteima having a gamma of 2.0

, is required in the blue sensitive emulsion E and The blue printing light for printing the yellow colored part image of the matrix is chosen so that the gradation of the yellow image in this a black-and white image having a gamma of 1.0 is required in th red sensitive emulsion F. Accordingly, the printing light employed for printing the yellow colorpart image D is selected so as to pass through the'spectral curve oi the yellow color part image D at the point where it registers a gamma of. 2.0 when measured through said image D, and the light for printing, the bluegreen or blue image C is selected in a similar manner to register a gamma of 1.0.

In the present instance, as seen by the illustration, the printing light is-selected so as to pass through the peak of the curve D in order to register a gamma of 2.0. On the other hand, the light selected for printing the blue-green or blue color part image must be selected so as to register a gamma of 1.0 when measured through said image and consequently passes through said curve C at a point well oif the crest of said curve. After the requisite silver part images have been recorded in the proper gammas in the emulsion layers E and F, they may then be developed in the ordinary manner and without special treatment.

The dyes contained in the emulsion layers E and F are unaffected by the development of the silver images but are susceptible to destruction in the presence of the silver images with the aid of suitable solutions. Accordingly, after the development of the silver images, the film is then treated in a dye destructionbath such as a Thiacarbamide solution as disclosed in my United States Patent No. 2,020,775. The treatment in this bath locally bleaches the dye in the presence of the metallic silver so that the emulsion layers thereafter contain both a silver image and a dye image. By bleaching the silver images in a suitable bath, such as a 10% cupric chloride solution, the emulsion layers may thereafter be fixed and contain only the dye images.

The expression "master image used herein is intended to connote any image from which a print may be made in a photographic printing. process by interposing the image between the source of printing light and the printing layer, whether said image be a monochrome or multicolor image, and whether the same is an original or a copy,

Although certain specific embodiments of the present invention have been shown and described, many modifications thereof are possible, and the present disclosure should be construed only in an illustrative sense. The present invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and the spirit of the appended claims.

I claim: v I 1. The process of producing photographic multicolor prints from a multicolor printing prototype containing color separation records in the form of differently colored part images by printing said part images in superposition on to the individual light-sensitive layers of the multilayer printing film, developing the prints in the respective layers of said printing film, and converting the superposed prints into differently colored part images by a coloring process yielding dye images of essentially equal color gradation from silver images of unequal gradation, the multilayer printing film comprising layers of silver halide emulsion which are selectively sensitive for different spectral ranges of light the color of the part images of the printing prototype being absorbent for light of said diiferent spectral ranges respectively, the light used in printing from said prototype on to said light-sensitive printing film being selected within said different spectral ranges, respectively, and of such spectral com position that the products of the color gradation of each individual part image of the prototype multiplied by the contrast of that emulsion of the printing film into which the part image is printed when exposed to such light are in the same ratio as are the gradations of silver images which by said coloring process are transformed-into dye images of essentially equal color gradation.

2. The method of printing into photographic multilayer materials comprising at least two light sensitive silver halide emulsion layers that are selectively sensitive for different spectral ranges, to obtain color images of substantially equal gradation in said layers, from master images comprising at least two part images colored to absorb light insaid different spectral ranges, respectively, which comprises printing each of said colored part images with light of a spectral range so selected that the ratio between the'productof the gradation of each of the colored part images when measured in its corresponding printing light times the contrast of the emulsion into which it is to be printed, and the product of the gradation of each of the other colored part images in its corresponding printing light times the contrast of the emulsion into which itis to be printed, is substantially the same as the. ratio between the gradations of each of the silver images required in said emulsion layers for the production'of color images therein having substantially equal gradation.

3. The method of printing into photographic multilayer materials comprising at least two light sensitive silver halide emulsion layers that are selectively sensitive for different spectral ranges, to record silver part images of unequal gradation that may be converted into color images of substantially equal gradation in said layers, from master images comprising at least two part images colored to absorb light in said different spectral ranges, respectively, which comprises printing each of said colored part images with light of a spectral range within the spectral sensitivity of the emulsion layers of the material, said light being so selected Within the absorption range of the colored part images that the ratio between the product of the gradation of each of the colored part images when measured in its corresponding printing light times the contrast of the emulsion into which it is to be printed, and the product of the gradation of each of the other colored part images in its corresponding printing light times the contrast of the emulsion into which it is to-be printed, is substantially the same: as the ratio between the gradations of each of the silver images required in said emulsion layers for the production of color images therein havin substantially equal gradation.

4. The method of printing into photographic multilayer materials comprising at least two light sensitive silver halide emulsion layers that are selectively sensitive for different spectral ranges, to record silver part images of unequal gradation that may be converted into color images of substantially equal gradation in said layers, from master images comprising at least two part images colored to absorb light in said different spectral ranges, respectively, which comprises printing each of said colored part images with light of a spectral range within the spectral sensitivity of the emulsion layers of the material, said light being so selected within the absorption range of the colored part images that the ratio between the product of the gradation of each of the colored part images when measured in its corresponding printing light times the contrast of the emulsion into which it is to be printed, and the product of the gradation of each of the other colored part images in its corresponding printing light times the contrast of the emulsion into which it is to be printed, is substantially the having substantially equal gradation, said multilayer -trast of the emulsion equal gradation,

same as the ratio between the gradations of each rotv the silver images required in said emulsion layers {or the production of color images therein gradation, developing saidprinted records into silver images of unequal' gradation, and converting said silver images into colored part images 01 equal gradation. 5. The process of producing multicolor photographic prints from a multicolor master image comprising differently colored part images by a process yielding color images of substantially equal color gradation from silver images of unequal gradation, whichcomprises printing said part images in superposition into a multilayer material to record silver part images or unequal material being composed of at least two light-sensitive emulsion layersthat are selectively sensitive for the spectral ranges of light respectively absorbed by the part images of said master image, the printing light being so selected within the absorption range of the part images or the master image that the ratiobetween the product of the gradation of each or said colored part images when measured in its corresponding printing light times the coninto which it is to be printed, and the product of the gradation of each of the other colored part images in its corresponding printing light times the contrast of the emulsion in which it is to be printed issubstantially the same, as the ratio between the gradations of each of the silver images requisite in said emulsion layers for the production of color images having substantially equal gradations; and converting by said process the silver images into differently colored part images of substantially equal color gradation.

6. The process of. producing multicolor photographic prints from a multicolor master image comprising differently colored part images by a process yielding color images of substantially equal color gradation from silver images of unwhich comprises printing: said part images in superposition into a multilayer material to record silver part images of unequal gradation, said multilayer material being composed ofatleast two light-sensitive emulsion layers that are selectively sensitive for the spectral ranges of the light respectively absorbed by the part images otsaid master image, the printing light being so selected within the absorption range of the part images or the master image that the ratio between the product oi the gradation of each of said colored part images when the gradations of each of the silver images requisite in said emulsion layers for the production of color images having substantially equal gradations, developing the record in the respective layers into silver images of unequal-gradation; and by said process treating the silver images in a bath which acts to form dye part images of substantially equal color gradation.

7. The process of producing multicolor photographic prints from a multicolor master image comprising diiierently colored part images byva process yielding color images of substantially equal colorgradation from silver images of unequal gradation, which comprises printing said part images in superposition into a multilayer material .to record silver part images of unequal gradation, said multilayer material being'composed of at least two light-sensitive emulsion layers that are selectively sensitivefor the spectral ranges of light respectively absorbed by the part images of said master image,,at least one,

of said layers being dyed with a dye which is fast to ordinary photographic treating solutions but capable of being locally bleached in the presence of a metallic silver image, the printing light being s0 selected within the absorption range of the part images of the master image that the ratio between the productoi the gradation of each of said colored part images when measured in its corresponding printing light times the contrast oi the emulsion into which it is to be;printed, and the product of the gradation or each of the other colored part images in its corresponding printing light times the contrast of the emulsion into which it is" to be printed, is substantially the same as the ratio between the gradations of each of the silver images requisite in said emulsion layers for the production of color images having substantially equal gradations, de-

veloping the records in the respective layers into silver images of unequal gradations, and converting by said process the silver images into ditferentlyf colored part images 01. substantially equal color gradation by locally bleaching the dye in at least the one of said 'dyed layer in proportion to the silverimage in said layer.

BELA GAsPAn."

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