US2518739A

US2518739A - Method of masking photographic color images

Info

Publication number: US2518739A
Application number: US758990A
Authority: US
Inventors: Richard V Young
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1947-07-03
Filing date: 1947-07-03
Publication date: 1950-08-15
Anticipated expiration: 1967-08-15

Description

Patented Aug. 15,1950

I was) :sTATEs oF Fi-cE Richard V. Young, Rochester,f3N. Y. assignor to Eastman Kodak Company,?Rochester, N. Y., a corporation ofNewJersey No Drawing. ApplicationJulyi'it,1947,

Serial No. 758,990 y 1 Claim.

This invention relates to photography and particularly to'a method of masking photographic color images. v v

It is knownthatdyesused in subtractive multicolpnphotographic pictures do 1 not transmit all of the light which theoretical-1 considerations demand. The cyan dye which shouldabsorb red light and "transmit green and bluelight usually absorbs a small amount ofgreen and blue-light as well-es a-major proportion of red light. The magenta dye which should absorb green light an'ditransmit blue an red light usually absorbs a considerable amount of blue light and a small amount of red light. The yellow dye which should absorb blue light and transmit green and red light is more generally satisfactory although sometimes it absorbs a small amount of green light. The result of printing a multl-color picture formed of such dyes is to introduce unequal parts of all three color records in each image which is made regardless of the color of light which is used in printing or the sensitivity of the printing material employed. Correction of the colors during printing is therefore desirable and this is usually done by masking as described in prior patents such as Evans U. S. Patent 2,203,653 and Hanson U. S. Patent 2,294,981.

In order to avoid the difficulty of registering the masking image with the picture image, it is desirable to have the mask integral with the color picture images. A method of producing an integral colored mask involving the use of colored couplers in a color coupling process is described in Hanson U. S. application Ser. No. 533,910, filed May 3, 1944, now Patent No. 2,449,966 of September 21, 1948. According to the method of the Hanson application, azo dye derivatives of couplers are used which are destroyed wherever a dye image is formed by color coupling.

I have found a method by which masking images may be produced in a photographic emulsion layer containing color developed dye images, the mask being colored as required by theoretical considerations and being integral with the picture image.

According to my invention a single layer or multi-layer photographic film having color couplers in the emulsion layer or layers is exposed and developed to negative color images by development with a primary aromatic amino developing agent. This produces the usual azomethine or indaniline dyes in the emulsion layers, leaving residual silver halide and uncoupled coupler in the unexposed portions of the layers. The film is then flashed or uniformly exposed and deprior patents and publications.

dye f masking images in *.the residual 1 portions of the layers. 1

The use of aromatic 'hy'drazines gas photo-5 graphic developing agents has been suggested: in Woodward and McQueen 2,339,213 describes 'the use of aromatic hydrazinesltodevelop a colored image in a photographic "layer by :combining with phenolic or active methylene compounds iofithe type used as color ='couplers. The reaction of "the "hydrazine developer'is suchthat during development of a silver halidethe' hydrazineis oxidized to a diazonium salt which reacts with the coupler in the layer to form an azo dye.

The coupler which I use in the red-sensitive layer of a multi-layer photographic film will be a phenol or naphthol derivative which yields a cyan indaniline or indophenol dye but which produces a red or orange azo dye by coupling with the hydrazine developer. The orange or red dye should absorb the blue and green light which the cyan dye should transmit and thus affect a masking or color correction of the cyan dye image in the well-known manner.

Similarly, the green-sensitive layer of the photographic element will contain a color coupler such as a cyano acetyl or pyrazolone derivative which yields a magenta azo methine dye but which produces a yellow azo dye with the hydrazine developer. The yellow dye will compensate for the blue light absorption of the magenta 'dye by maintaining constant blue light absorption through the magenta layer.

Suitable aromatic hydrazines which may be used as developing agents according to my invention are phenyl hydrazine, p-phenylchloro hydrazine, p-nitro phenyl hydrazine, 2,4-dinitro hydrazine, a-naphthyl hydrazine and b-naphthyl hydrazine.

My invention will be more clearly understood by reference to the following specific example.

A multi-layer photographic film containing couplers such as described in Jelley and Vittum U. S. Patent 2,322,027 is exposed to an image or object and color developed in a primary aromatic amino developer such as that disclosed on page 5 of Jelley and Vittum Patent 2,322,027. The film is then washed andpflashed with white light and developed in a hydrazine developer of the following composition:

Grams Phenyl hydrazine 2 to 10 Sodium carbonate 20 Water to 1 liter.

red-sensitive layer and developing it in a suitable hydrozine developer and then repeating the procedure with the green-sensitive layer and de-' veloping it in a second hydrazine developer. This method affords a more satisfactory method of controlling the composition of the masking dye formed in the two layers since it is not always possible to obtain a mask dye of a satisfactory color with a single hydrazine developing agent.

Where I refer to color couplers, it will be understood that I refer to the usual phenolic, naphtholic, or active methylene couplers which form indophenols, indaniline or azomethine dyes by coupling with the development product of a primary aromatic amino developing agent such as para-phenylenediamine, para-aminophenol, or their derivatives.

I claim:

The method of producing a color correcting image in a multi-layer photographic film having a silver halide emulsion layer sensitive to the red spectral region and containing a color coupler capable of producing a cyan dye, a silver halide emulsion layer sensitive to the green spectral region and containing a color coupler capable of producing a magenta dye, and a silver halide emulsion layer sensitive only to the blue spectral region and containing a color coupler capable of producing a yellow dye, all of said dyes being formed by coupling with the development product of a primary aromatic amino developing agent, said method comprising exposing said film to an object, developing negative silverand dye images therein by treating said layers with a primary aromatic amino developing agent, exposing said red-sensitive layer with red light and said greensensitive layer with green light, developing said layers after each exposure of said green-sensitive and red-sensitive layers with a different aromatic hydrazine to form a red to orange positive azo dye image in the red-sensitive layer and a yellow positive azo dye image in the green-sensitive layer, and allowing said negative dye images and said positive azo dye images to remain in said film.

; RICHARD V. YOUNG.

REFERENCES CITED.

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

UNITED STATES PATENTS Woodward et al. Jan. '11, 1944