US2449966A - Integral mask for color film - Google Patents

Description

Sept. 21, 1948. w. T. HANSON, JR 2,449,966

INTEGRAL MASK FOR COLOR FILM Filed May 3, 1944 FIG. I.

CYAN C DYE YELLOW AGENTA Q DYE DYE [1.] D

.l 2 l- O. O

l I 400 500 600 700 FIG WAVE LENGTH B G R 40 RED ABSORPTION 6 M -GREEN ABSORPTION z P VBLUE ABSORPTION 4m 1.06. E LOG. E LOG .E

8 LBLUE &GREEN ABSORPTION PRINTED u RFD ABSORPTION INVENTOR BY mfw (3 MM A TTORNE YS WESLEY T. HANSONQJR.

' Patented 21, 1948 INTEGRAL MASK FOR COLOR FILM Wesley '1. Hanson, In, Knoxville, Tenn., assignor to'Ealtman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application May 3, 1944, Serial No. 533,910 7 Claims. (Oi. 95-2) This invention relates to photography and particularly to a method for securing color correction in color transparencies used for printing.

It is known that dyes used in subtractive multicolor photographic pictures do not transmit all of the light which theoretical considerations demand. The cyan dye which should absorb red light and transmit green and blue light usually absorbs a small amount of green and blue light as well as a major proportion of red light. The magenta dye which should absorb green light and transmit blue and 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 usually satisfactory although some-- times it absorbs a small amount of green light. The result of printing a multi-color picture formed of such dyes is to introduce unequal parts of all three records in each image which is made, regardless of the color of light used in printing or the sensitivity of theprinting material employed. Correction of the colors on printing is therefore desirable, and this is usually done by masking, as described in prior patents, such as Evans '0. S. Patent 2,203,653, granted June 4, 1940, and my prior Patent 2,294,981, granted September 8, 1942.

Since separate masks are diiiicult to register with the color picture, it is desirable that the mask be integral with the colored images. The Evans U. 8. Patent 2,203,653, referred to above describes a method for making an integral mask in a multi-layer reversal material, but the mask is black or gray in color and does not secure the advantages of colored masks such as described in Evans U. 8. application Serial No. 413,442, filed October 3, 1941, now U. S. Patent 2,376,132, granted May 15, 1945.

One type of color process in which it would be desirable to introduce color correction is that in which a, color coupler is incorporated in the sensitive emulsion layer prior to exposure. Processes of this type are described, in Mannes and Godowslay Patent 2,304,940, granted December 15, 1942, and Jelley and Vittum U. 8. Patent 2,322,027,

granted June 15, 1943. These processes are particularly useful as negative-positive processes, a

in the negative perior making corrected my invention by incorporating in the sensitive the dye may be emulsion layer a colored material especially a color coupler which absorbs the undesired absorption of a dye reduced in image form in the layer. In case the colored material is a coupler, produced by coupling from the coupler itself thereby destroying the coupler in the portions of the layer in which an image is formed and leaving the coupler unailected in the remaining portions of the layer.

In the accompanying drawing,

Figure 1 is a, graph illustrating the spectral absorption of representative dyes used in subtractive color processes.

Figure 2 is a graphic representation of the relative absorptions of representative subtractive dyes obtained by plotting the exposure expressed logarithmically against the optical density in various regions of the spectrum.

Figure 3 is a representation, partly sectional and partly graphical, of a photographic layer employing the correction method of my invention and showing the correction obtained on printing.

In describing my invention, it will be necessary first to refer to the spectral absorption properties of typical dyes used in subtractive color procesess as illustrated in Figures 1 and 2 of the drawing.

Figure 1 shows the absorption curves of typical subtractive dyes, yellow, magenta and cyan. If the optical density of each or these dyesat various wave lengths is determined, the graphs shownin Figure i may be obtained. The yellow dye absorption is principally in the blue region between 400 and 500 millimicrons, although there is some absorption in the green region between 500 and 600 millimicrons. The magenta dye absorbs principally in the green region, although there is a considerable absorption in the blue region and a smaller absorption in the red region between 600 and 700 millimicrons. The cyan dye absorbs principally in the red region, although there is a considerable absorption in both the blue and the green spectral regions. These characteristics are fairly common to dyes generally used. although the absorptions are not identical with those shown in Figure 1. producing such dyes are described in numerous prior patents such as Marines et al. U. S. Patents 2,039,730, granted May 5, 1936, 2,108,602, granted February 5, 1938, and 2,115,394, granted April 26, 1938. In Figure 1 it is assumed that the relative concentrations of the dyes are adjusted so that when layers containing the three dyes are superposed, a neutral gray image is produced.

The absorption of the dyes of Figure l in the various regions of the spectrum are illustrated in the graphs of Figure 2. The separate graphs indicate the absorption gamma of each dye in one of the three regions of the visible spectrum. The horizontal rows 01 parts Y for example illustrate the absorptions of the yellow dye in the blue, green and red regions of the spectrum. The principal or major absorption of the dye is indicated by a solid line, and the minor absorptions by dotted lines. The graph YB therefore illustrates. the absorption of the yellow dye in the blue region, the graph MG illustrates the absorption of the magenta dye in the green region and the graph CR illustrates the absorption of the cyan dye in the red region.

The curves of Figure 2 are H and D curves of the dye images in various spectral regions and are said to represent absorption gamma, that is, the H and D curve of the dye image as read by light of any spectral region. For example, the curve YB represents the absorption gamma of the yellow dye whenread by blue light.

It is apparent from the graphs of Figure 2 that in a duplication process, blue light will be absorbed not only by the yellow dye but also to some extent by the magenta and cyan dyes. Similarly, green light will be absorbed not only by the magenta dye but also to a certain extent by the yellow and cyan dyes. Red light will be absorbed not only by cyan dye but also to a small extent by the magenta dye. This lowers the saturation of the dyes in the print and tends to make the colors dirty or degraded. The known masking methods seek to overcome this objectionable feature of the dyes by inserting a density which cancels out the undesired absorptions of one or more of the dyes.

It is apparent from a consideration of Figure 2 of'the drawing that if the absorptions CB and- CG of the cyan dye could be canceled by placing over the cyan image an image of opposite sign and absorptions equal to the absorptions CB and CG, the efiect would be to introduce a neutral density in these regions without affecting the absorptionCR. The manner in which this is accomplished according to. my invention is illustrated in Figure 3 of the drawing.

Figure 3 is in the form of a cross-section of an emulsion layer containing dye images. according to my invention, the dye images being illustrated Color couplersby means 01' their absorption gamma for the purpose oi illustration. The sections la and 4b of 6, I, and 8.

Figure 3 are portions of the same layer but are separated for purposes oi! clarity in illustration. As shown in 4a, the emulsion layer contains a cyan dye image, the red absorption gamma 0! which is illustrated by curve 5. The cyan dye image has minor absorptions of green and blue light as illustrated by the-absorption gamma I and 1 respectively. These curves correspond to the curves CR, CG, and CB, respectively, but are superposed in Figure 3.

in the same layer as the cyan dye in at, there is a coloring material having an absorption gamma illustrated at 8 in 4b which is equal and opposite in gamma to the gamma 0! 6 or I or the average of these gammas. It is opposite in sign, that is it is a positive image when 6 and I represent a negative image. Since the coloring material represented at 8 has blue and green light absorption, it adds to the blue and green absorption of the cyan dye as represented at 6 and 'l and therefore produces the same result as removing the absorptions represented at 6 and I, by converting them into non-image-forming, overall blue-green absorbers.

When the negative image in 4a is printed onto the film 9 the effect of the over-all blue-green absorption is illustrated as a straight line l0 and the absorption gamma of the cyan image is illustrated at II. It will be seen that the contrast oi the cyan image to blue and green light is reduced to zero because of the combined effect of images More blue and green exposure is therefore required in printing those records, and the contrast of the yellow and magenta images must be. raised, either in the original or in the print.

' sky U. 5. Patent 2,304,940 or the Jelley and Vittum U. 8. Patent 2,322,027, referred to above. The coupler need not be incorporated in a. waterpermeable, water-insoluble solvent as described in those patents but may be incorporated in insoluble or non-difiusing form in the emulsion. The

coupler is colored so that it absorbs light prior to coupling but upon coupling is converted to a form which absorbs the color desired for the final dye image. The color of the original coupler is chosen so that it absorbs light of the same color as the undesired absorption of the dye formed from it. In this way, the colored coupler can correct for the improper absorption of the coupled dyes and thus effect complete masking. Depending upon the correction desired, the cyan coupler should be red, orange or yellow, the magenta coupler yellow or green and the yellow coupler magenta or blue. The reason for choosing-these colors is apparent from a consideration of Figure 2 of the drawing.

The red, orange, or yellow coupler used for the cyan dye absorbs blue or blue and green lightwhich the cyan dye also absorbs but which it should transmit. The yellow coupler used for the magenta dye absorbs 'blue light which the magenta dye absorbs but which it should transmit. The magenta coupler used for the yellow dye absorbs green light which the yellow dye absorbs to a small extent but which it shouldtransmit. The following couplers describedin application Serial Nos. 533,930, 533,931 and 533,932, flied cases a May 8,184, by Glass, vittum and Weissberger are suitable for use according to my invention:

.velopment of the re Colorol Coupler 832: Coupled CcBrN\ l in-N=N-c.nr-on 4 Ycllowm. Magenta.

CoKr-CO-H-N=NCQKI man .Do.

, coon do Do. CN c0-cHN=N o no N=NCsHr-OCH1(4) Red Blue.

I- Cu u(fl) CsEr-N\ l conN=N- 0om Yellow-... Magenta. a.

N COOH Red Cyan.

1. CO-NH CQHI mm-co-ln-rvmLQmm Orange-red Yellow.

Analternative method of introducing the correcting image into the emulsion layer is to use, instead of a colored coupler, a dye which can be bleached in the presenceof silver. If such dye is introduced into the emulsion layer along with the coupler, the choice of coupler is not limited to the color which it has before coupling, and there is also a. wider choice of bleachable dyes. If a red or orange dye is incorporated in the red-v sensitive layer for example, a positive image will be obtained from this dye if, after negative color development, the film is immersed in a bleached bath which destroys the masking dye in the presence of silver but does not affect the dye formed by coloring. In the presence of the negative silver image, the dye will be bleached and will leave a positive image.

It is apparent that the masking image used according to my invention is oi sign opposite to that o! the image dye. I! the image dye is a negative, the masking dye will be a positive and vice versa. Where I refer in the claims to a negative color image, it is to be understood that I mean that it is negative with regardto the masking image orof opposite sign. It may be. any image which-is printed either from a negative or a positive.

While I prefer to use my method in a negativepositive process, it is also applicable to a reversal process. Where the masking image is a colored coupler, a. .black-and-white negative developer must be used and the negative silver thus formed may be leit in the film until after the color desilver image of a reversal process must be removed before reversal development and bleaching of the dye.

The following example illustrates one method of producing a corrected image according to my invention.

Example sensitive layer containing a coupler yielding a magenta dye image, (4) yellow filter layer, and (5) blue-sensitive layer containing a coupler yielding a yellow dye image. This example will showa material in-which a colored coupler is used in the green-sensitive layer to provide a corrected magenta dye image. The details of the preparation of the several layers are given in the following paragraphs.

Red-sensitioe layen-This is prepared accordm to the description '-in Jelley and Vlttum U. s.

Patent 2,322,027; page-i, Example 2. The coupler employed is 5(N-benzyl-N-naphthalene sulfonamino) 1-naphthol, dispersed in ethyl N ,N-di-m butyl carbamate, and the emulsion to which it is added is red-sensitized by known means.

Green-sensitive lawn-The coupler used in.

this ,layer is 1-phenyl-3-n-pentadecyl-4-p-me thoxyphenylazo-S-pyrazolone. This coupler is yellow and reacts with the oxidized developer to produce a magenta dye. Seven and a halt grams silver halide: It the masking image is a bleachable dye. "the negative of the coupler are dissolved in 22.5 g. of tri-ocresylphosphate by gentle warming and this solution is emulsified with 40 cc. oi. 2% gelatin solution containing 1.5 g. of tri-isopropylnaphthalone sulfonate by passing the whole mixture through a colloid mill several times. The resulting emulsion is added to 1,000 cc. of a melted silver halide emulsion which has beensensitized to green. and the mixture coated over the redsensitive layer described above.

Yellow-filter lawn-This layer contains yellow colloidal silver a known from the prior art.

Blue sensitive layer.'1his is prepared according to the description in Jelley-& Vittum U. S.

2,322,027, page 4, Example 6. The coupler employed is N (4 benzoylacetaminobenzonesulfonyD-N-benzyl-m-toluidine, dispersed in ethyl benzylmalonate.

The composite coating prepared in the above manner is developed in the following solution, after exposing in the normal manner:

2-amino-5-diethylaminotoluene hydrochloride grams 2 Sodium sultlte (anhydrous) do 2 Sodium carbonate, monohydrate do 20 Potassium bromide do 2 Water c 1,000

The time of development will depend on the nature of the particular silver halide emulsions employed. Development is followed by an acid hardening fixing bath and a silver removal bath according to well known practices.

The processed material thus obtained will contain a normal negative image in cyan dye in the red-sensitive layer, and a normal negative image in yellow dye in the blue-sensitive layer. The green-sensitive layer will contain a negative image in magenta dye, and the residual coupler will make a reversed image of yellow coupler.

This negative image can be printed onto a normal multi-layer printing material for the production of three-color photographs.

Instead of introducing the colored coupler to the sensitive emulsion layer, the sensitive layer may be treated with a diazonium salt solution prior to color development in order to produce the colored coupler in the layer. A variety of diazonium solutions may be used for this purpose, and the time during the production of the film to which the reaction with the diazonium solution is carried out may also be modified. Either of these conditions may be changed to give a number of diii'erent results. For example, the diazo coupling can be carried out when only part of the layers have been coated, that is, when only the red-sensitive layer or only the redand green-sensitive layers have been coated. Diazo coupling 01' the complete multi-layer material can also be carried out at difierent times, such as before or after exposure. In the case of multilayer coatings, the character of the couplers and sults and will vary according to the desired ab-'.

sorption to be gained and to the ease with which it may be handled. In general, however, the procedure is rapid and complete and may be modified in a number of ways as shown above.

As a specific example of the preparation of a colored coupler in this way, agreen-sensitive emulsion, such as that described in the specific example above but using as the coupler -(pbutylphenoxy) propionyl aminoJ-S-pyrazolone is treated as the'exposure but before color development with a diazonium solution prepared in .the following manner.

1.2 grams p-anisidine (0.01 mole) dissolved in cc. of water and 5 cc. of concentrated hydrochloric acid is diazotized with 1.5 grams sodium nitrite in 15 cc. water at 5-10 C. The excess of nitrous acid is destroyed with sulfamic acid, and cc. 01' a 10% sodium acetate solution is then added. The resulting solution is then used for the diazo coupling at a temperature between and F., the film being left in it anywhere from a few seconds to about ten minutes at which time coupling is complete.

The masking method which I propose to use has all the advantages of known masking methods with the additional advantages of the colored mask described in Evans U. S. application Serial No. 413,442, now U. S. Patent 2,376,132, and the advantages of an integral mask. Lack 01' registry between the mask and the picture image is no problem with my invention.

It is thereby understood that the modifications and examples discolsed herein are by way of example only and that I consider as included in my invention all modifications and equivalents coming within the scope of the appended claims.

I claim:

1. The method of forming a color corrected image in a photographic element having superposed silver halide emulsion layers sensitive to difierent regions of the visible spectrum, at least one of said layers containing a colored color coupler for color-forming development having a chromophore-containing group in the position in the coupler which is reactive with the oxidation product of a primary aromatic amino developing agent, said chromophore-containing group being split off with simultaneous conversion of the residual group 01' the colored coupler to coupled dye by color development to form a dye image which absorbs a major proportion 01' light in the spectral region oi. one of the primary colors and a minor proportion 01 light in at least one other region of the visible spectrum, said colored coupler absorbing light in at least one of said minor absorption regions but absorbing no substantial amount of light in said major absorption region, which comprises exposing said layers to light and developing at least said layer containing said colored coupler by color development with a primary aromatic amino developing agent, said color development resulting in splitting off the chromophore-containing group of said colored coupler where said dye image is formed by coupling, leaving in the undeveloped regions of said one layer colored coupler absorbing light in said minor absorption region or said dye image.

2. The method oi. forming a color corrected image in a photographic element having superposed silver halide emulsion layers sensitive to different regions of the visible spectrum, at least one of said layers containing a dispersion in a water-permeable, water-insoluble solvent, of a colored color coupler for color-forming development having a chromophore-containing group in the position in the coupler which is reactive with the oxidation product of a primary aromatic amino developing agent, said chromophore-consion of the residual group taining group being split of! with simultaneous conversion or the residual group of the colored coupler to coupled dye by color development to form a dye image which absorbs a major proportion of light in the spectral region of one of the primary colors and a minor proportion of light in at least one other region of the visible spectrum, said colored coupler absorbing light in at least one or said minor absorption regions but absorbing no substantial amount of light in said major absorption region, which comprises exposing said layers to light and developing at least said layer containing said colored coupler by color development with a primary aromatic amino developing agent, said color development resulting in splitting ofl the chromophore-containing group of said colored coupler where said dye image is formed by coupling, leaving in the undeveloped regions of said one layer colored coupler absorbing light in said minor absorption regions of said dye image.

3. The method of forming a colored corrected image in a photographic element having superposed silver halide emulsion layers sensitive to different regions of the visible spectrum, at least one of said layers containing a colored color coupler tor color-forming development having an azo group in the position in the coupler which is reactive with the oxidation product of a primary aromatic amino developing agent, said azo group being'split ofl with simultaneous conversion of the residual group of the colored coupler to coupled dye by color development to form a dye image which absorbs a major proportion of light in the spectral region of one of the primary colors and a minor proportion of light in at least one other region of the visible spectrum, said colored color coupler absorbing light in at least one of said minor absorption regions but absorbing no substantial amount of light in said major absorption region, which comprises exposing said layers to light and developing at least said layer containing said colored coupler by color development with a primary aromatic amino developing agent, said color development resulting in splitting of! the azo group of said colored coupler where said dye image is formed by coupling, leaving in the undeveloped regions of said one layer colored coupler absorbing light in said minor absorption region of said dye image.

4. The method of forming a color corrected image in a photographic element having superposed silver halide emulsion layers sensitive to diflerent regions of the visible spectrum, at least one of said layers containing a colored color couimage in a pler ior color-forming development having an v azo group in the position in the coupler which is reactive with the oxidation product of a primary aromatic amino developing agent, said azo group being split off with simultaneous converto coupled dye by color development to form a cyan dye image which absorbs a major proportion of red light and a minor proportion of visible light of shorter wave length than red, said couof the colored coupler pler absorbing light insaid region of shorter 7 wave length but absorbing no substantial amount of red light, which comprises exposing said layers to light and developing at least said layer containing said colored coupler by color development with a primary ing agent, said color development resulting in splitting off the azo group or said colored coupler where said cyan dye image is formed by coupling, leaving in the undeveloped regions of said aromatic amino developone layer colored coupler absorbing light in said minor absorption region of said cyan dye image.

5. The method 01 forming a color corrected image in a photographic element having superposed silver halide emulsion layers sensitive to diflerent regions of the visible spectrum, at least one of said layers containing a colored color coupler for color-forming development having an azo group in the position in the coupler which is reactive with the oxidation product of a primary aromatic amino developing agent, said azo group being split oil with simultaneous conversion of the residual group of the colored coupler to coupled dye by color development to form a cyan dye image which absorbs a major proportion of red light and a minor proportion of blue and green light, said coupler absorbing blue and green light but absorbing no substantial amount of red light, which comprises exposing said layers to light and developing at least said layer containing said colored with a primary aromatic amino developing agent, said color development resulting in splitting oi! the azo group and destruction oi the color of said colored coupler where said cyan image is formed, leaving blue-green absorbing coupler in the undeveloped regions of said one layer.

6. The method of forming a color corrected image in a photographic element having superposed silver halide emulsion layers sensitive to diflerent regions of the visible spectrum, at least one of said layers containing a red colored coupler capable of forming a cyan dye by coloriorming development and having an azo group in the position in the coupler which is reactive with the oxidation product of a primary aromatic amino developing agent to form said cyan dye, said azo group being split oil with simultaneous conversion of the residual group of the coupler to a cyan dye by color development, which comprises exposing said layers to light and developing at least said layer containing'said red colored coupler with a primary aromatic amino developing agent to form dye images representing color separations of a subject. one of said color separations being formed by color development of said red colored coupler to a cyan dye, said color development resulting in splitting off the azo group and destruction of the color of said coupler where said cyan dye image is formed, leaving red colored coupler inthe undeveloped regions of said one layer.

7. The method of forming a color corrected photographic element having superposed silver halide emulsion layers sensitive to diflerent regions of the visible spectrum, at least one of said layers containing a yellow colored coupler capable of forming a magenta dye by color-forming development and having an azo group in the position in the coupler which is reactive with the oxidation product of a primary aromatic amino developing agent to form said magenta dye, said azo group being split of! with simultaneous conversion of the residual group of the coupler to a magenta dye by color development, which comprises exposing said layers to light and developing at least said layer containing said yellow colored coupler with a primary aromatic amino developing agent to form dye images representing color separations of a subject, one of said color separations being formed by color development of said yellow colored coupler to a resulting in splitting oil the azo group and decoupler by color development magenta dye, said color development 7 magenta dye image is formed, leaving yellow colored coupler in the undeveloped regions of iile of this patent: 1 1

UNITED STATES PATENTS Name Date Michaelis Mar. 19. 1940 Michaelis May 13, 1941 Schultze Jan. 5, 1943 FOREIGN PATENTS Country Date Great Britain Apr. 11, 1939

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