US1516824A - Color photography - Google Patents

Description

Nov. 25, 9 1,516,824

. L. D. MANNES ET AL COLOR PHOTOGRAPHY I Filed Feb. 20, 1925 2 Sheets-Sheet l Object to be Photographed BLACK wHrrE ORANGE-RED BLUEGREEN Before Exposure 5 After Exposure and Development BLACKliWHITE sensmows nsvensso RECORDS m RECORD'SIN IN GATIVE LOWER LAYER ONLY UPPER LAYER ONLY x\\b\\\\\\\\\\ W METALLIC sun-R 29 After Bleachihg Vf'R FERRO cm N/DE ATTORN EYI Nov. 25, 1924. 1,516,824

L. D. MANNES ET AL COLOR PHOTOGRAPHY Filed 20, 1923 2 Sheets-Sheet 2 After Redevolopmenl of upper Layer.

w O--R a-e MfT/ML /C 5/1 VER MET/411K 6/4 76/? 9&5 After Toning of lower Image 5 I w O-R 8-61 .MEMLt/C \SILVEI? IIETIll/C \SILVf/Y Finished Negative After Mordanldyeing The upper Image COLOR5 8; COLOR VALUES REVERSED W O-R B G1 COLORED ORA/V65 RED Finished Positive BLACK WHITE ORANGE-RED BLUE -QREN INVEETORs z W I ,0, m 4% ATTORNEY Patented Nov. 25,- 1924, I

' sir-as I-LIEOPOLD D. MANNES AND nnoronn GO'DOWSKY, an, or NEW YORK, N. Y.

COLOR PHOTOGRAPHY.

Application filed February 20, 1923. Serial No. 620,269.

To all whom it may concern,

'vented certain new and useful Improvements inColor Photography; and we do hereby declare the following to be a full,

clear, and exact description of the invention,

such as willenable others skilled in the art to which it appertains to make and use the same, V

. The present invention relates to the art of color photographyand has to do particularly with an improved process which may be satisfactorily employed for producing pictures commercially in substantially-the colors-of the original subject photographed.

, This 'applicationis in a sense a modifica- 'ess of color photography disclosed in our tion or further development over the procco-pnding application Serial No. 531,356,

filed January 24th, 1922. Color photographs are commonly produced by either a two color or a three color process.

'the subject photographed in substantially its natural colors.

' In color photography, partlcularly in the presentation of motion pictures, it is commen 1 to simultaneously or alternately pro- .jcct on the screen in superimposed relation a plurality of single color pictures equal in number to the color sensations employed,

the combination of' the various individual pictures resultingm a composlte picture containing all of the colors distributed ac-- cording to their occurrence in the individualsingle color pictures. It has also been proposed to prepare separate simultaneously taken negatives each recording a single color sensation, and to successively -print themin superimposed relation on a plate. or film, the prints then belng colored to reproduce the proper color values occurring in the originalsubject. The above methods are open to the objection that it is practically impossible to exactly superimpose the various individual pictures in order that the resulting picture may be without color fringe or similar objectionable efiect;

The color rendition'in the final plcture 1s, of course, somewhat more com-- It has also been proposed to provide a single plate or film sensitized on one side to record a certain color sensation and sensitized on the other side for a difierent color sensation, so that by a single exposure two images recording respectively the particular color sensations for which the coatings have been sensitized may be obtained. With this method, inasmuch as the two sensitized coatings are supported on the same film, one side of the film must be specially Water-proofed or otherwise protected While the image/on the other side is being developed and toned. This method is further limited to work in which only two exposures of different color sensations may be taken and is thus impossible of application to the three color process. As far as we are aware a process of color photography employing a film or other support bearing in a substantial unitary body a plurality of sensitized emulsions to record respectively a plurality of superimposed pictures of different color sensations, has not prior to our above mentioned co-pending application been successfully carried out.

It is an object of this invention to providean improved method for producing a finished picture in substantially natural colors wherein the color sensations are recorded by a single exposure and the development of the exposed film or plate is accomplished by a single operation in which the plurality of superimposed latent images are completely and simultaneouslydeveloped, the developed plate or film. recording the proper color values but being essentially a black and white negative which may be used for the production of ordinary black and white positives in the manner of an ordinary negative.

It is another object of the invention to pro vide a method for satisfactorily producing colored pictures which involves the production of a-color negative in which the colors of the respective images are reversed, and in which the color values in each image are also reversed.

It is a further object to provide a method of this nature in which the light used for printing-the positives may be modified or colored to thereby improve the color rendition on the resulting positive.

It is also an object to provide a method for producing color photographs which provides for correcting any inherent discrep-- ancies of internal contrast which might result fronithe use on the film or plate of slow and fast emulsions of different color sensitivity, to thus secure a faithful rendition of the final picture-in natural colors.

It is a still further object to provide a process of this character in which there is no necessity of removing orotherwise protecting a portion of the plate or film dur1ng the developing process, and in which the sensitized emulsions are placed immediately adjacent at 'one side of the film or plate so that the respective outlines of the 1nd1v1dual color images are exactly superimposed.

We have illustrated the steps of our im-' proved process in the accompanying drawing wherein Figure -1 represents the ob ect being photographed, the ob ect consist ng of 4 rectangular blocks colored black, white, orange-red and blue-green as indicated on the drawing; Figure 2 is a transverse sectional view showing the nature of film or plate before exposure; Figure 3 is a sinnlar view of the film or plate after exposure and development; Figure 4 shows the film or plate as it appears after the bleaching operation: Figure 5 illustrates the -eharactenof' the plate after the upper layer of emulsion is redeveloped; Figure 6 shows the plate after toning of the lower image Figure 7 illustrates the finished negative and Figure 8 shows the distribution of the images and colors on the-finished positive.

In carrying out our improved process we employ an appropriate transparent film or plate of the ordinary type and provide this plate on one surface with a plurality of sensitized coatings or emulsions as indicated in Figure 2. In a two color process two emulsions are employed. The transparent film or plate is first coated with a fast silver bromide emulsion sensitized to record the red or orange-red sensations in the subject being photographed. A second coating or emulsion is placed directly upon the first coating, this coating consisting-of a Slower silver bromide emulsion and forming with the first coating an essentially unitary layer or coating on the transparent film. This second coating is sensitized for the green or greenish-blue of the spectrum. Since the blue sensation ordinarily predominatesin photographic images it may be desirableto diminish the intensity of the blue rays by incorporating into the upper emulsion a strong yellow dye distributed uniformily throughout the body of the emulsion.'- This yellow dye serves as a screen to exclude all blue and violet rays from the lower emulsion and at the same time to exclude a portion of the blue light from the lower part of the upper coating and thus tone down the resulting blue-violet sensations which be recorded in the upper emulsion.

In making an exposure the film of Figure will- 2 comprising the two. superimposed emulsions forming essentially a single integral coating is supported in a camera of the ordinary type and a single exposure taken in the. ordinary manner. The light entering the camera first comes in contact with the emulsion sensitized for the blue-green of the spectrum, that portion of the light, which passes through this emulsion serving to atfect the lower layer of. emulsion. Inasmuch as a lesser quantity of light acts upon the lower coating this emulsion must be fast, and the two emulsions are so constituted that a complete exposure of each will occur in the same length of time. It will be understood that a compensating filter may be employed to regulate the time of exposure of either of the emulsions and in this manner a each portion of the film coating having recorded that color sensation for which it has been sensitized.

While it is possible to developthe film or plate by treating the two sensitized coatings successively our inventi'on contemplates the development of the two sensitized coatings at the same time and by the same operation. For this purpose a developer, such as metol (monometholparaminophenolsulphate) with 'a small alkaline content, which freely penetrates the material of the emulsions, is employed. The film is left in the developing solution until both images are completely developed whereupon the film is washedand the images fixed in the ordinary manner; In our above mentioned co-pending application we have described a process contemplat- -ing the development of the upper and lower images successively, coloring each one as it is developed by chemically toning the upper image and dye-mordanting the lower image. In that application we ialso described a proc ess contemplating the'simultaneous develop ing of both the upper and lower image and then suitably coloring the respective images by toning the upper image anddye-mordanting the lower image in the manner above mentioned. It is to benoted that the negative resulting from-the simultaneous development of the two layers of emulsions is a black and white plate in which the color values of the subject photographed are corgarded as an ordinary photographic nega-- reotly represented, but in which, of course,-

tive and may be used as desired for the production of black and white prints ofthe subject. The characteristics of the film or plate at this stage of the process. are illustrated in Figure 3. It will be noted that Orange-red of the object records only in the lower layer of emulsion while theblue-green of the object records only in the upper layer. This arrangement of the images formed is indicated in the figure.

After the film or plate containin the two superimposed images has been completely developed and fixed so that the black and white negative results, this negative is ready for the coloring process to form a color negative from which the finished picture may be printed. plates the production of a color negative by first bleaching th developed images. The bleaching is accomplished by immersing the film or plate after development in a suitable bleaching solution, such as for instance a solution of potassium ferri-cyanide, and allowing it to remain in the solution until both images are completely-bleached. VYe have found that the addition of a small quantity of ammonia to the solution of potassium ferri-cyanide is advantageous and assists in the producing of a proper bleaching. Theeffect of the potassium ferri-cyanide solution is to react on the lmages formed in the emulslon, converting them to silver ferro-cyamde.

, It will be noted that the distribution of the images in the body of emulsion'is identical with that of Figure 3, the only difference being that after bleaching (illustrated in Figure 4) the metallic silver of the developed images is converted to silver ferro cyanide. In

this step of the process there is nodanger of overbleaching the image's orbleaching one more than the other so that the only precaution which need be taken is to allow. the plate to remain in the bleaching solution for a time sutliciently long toinsure complete bleaehing'of the images. The plate is then withdrawn from the bleaching solution and washed and dried in the usual manner.

After bleaching out the images in this manner the upper image is redeveloped to its original silver state. This step is illustrated in Figure 5 wherein the images recorded in the upper layer of emulsion are converted back to metallic silver while the images recorded in the lower layer are still silver ferro cyanide. This is accomplished by the use of any well-known photographic developer, a strong solution of the developer being ordinarily required, diamidophenol being preferable. The plate is permitted to remain in the developing solution until the upper image, that is the image occurring in the upper strata of the emulsion on the film or plate, has been developed to its original state.

Our improved process contem- The developing action must, how-' ever, be checked'before the lower image is affected. Inasmuch as the upper image does not extend throughout the entire thickness ofthe strata of emulsion sensitized to receive that image, there is an appreciable time latitude between the completion of the-developing of the upper image and the beginning of the action of the developer on the lower image. The developingsolution works from the surface of the emulsion down, and for this reason there is ample opportunity to withdraw the plate from the developing solution after-the upper image has been completely developed without experiencing a partial development of the lower image also.

Upon withdrawal from the developing solution the plate is, of course, washed to remove the developer. The addition of a little acetic acid to the wash water is beneficial in effecting a more thorough and complete washing of the plate.

According to our invention we color the lower image, that is the image which is recorded in that. portion of the emulsion originally sensitized to record the orange-red sensations, blue or bluish-green, preferably bluish-green. To accomplish this the plate bearing the bleached lower image andhaving theupper image redeveloped,-may be treated by immersing in any suitable solution containing a soluble ferrous salt, preferably ferrous chloride. The ordinary ferric,

chloride solution -may be used, or in fact any of the solutions containing ferric salt,

but we have found that there are certain disadvantages inherent in the use of solutions of this character for instance, the'use of ferric chloride solution results in .a certain chemical combination with the material on the plate and has a tendency to impair the character of the final texture by preventing a clear transparent image being formed in the subsequent steps of the treatment to which the plate is subjected. The ferric lent results when employed in our process and is not subject to the disadvantages and limitations incident upon the use of a ferric chloride solution. Upon immersion in such a. solution the lower bleached image on-the plate, which now consists of silver ferrocyanide, reacts with the constituents of the solution to form ferric or ferrous ferrocyani'de. Thus the entire lower image will be colored blue whereas the redeveloped upper image will not be aflected by the acid iron solution and will, therefore, remain unchanged. To incorporate a certain amount of green into the coloring of the lower image a soluble salt of vanadium may be added to the iron containing'solution, the amount of the vanadium salt added depending on the amount of green coloring which it is desired to incorporate intothe image. This step is' illustrated in Figure 6. After this coloring operation the plateis washed and is imv mersed in a sodium thiosulfatesolution, for

the purpose of dissolving whatever soluble silver salts remain in the lower image and (A) is prepared which consists of copper sulphate 3 grams, potassium citrate 12 grams, water 500 c. c., and a second solution (B) consisting of potassium ferric-yanide 2 grams, potassium citrate 12 grams, water 500 c. 0., equal parts of solutions' A- and B are mixed together and the resulting mixture consitutes the mordanting bat-h. This bath converts the silver images in the emulsion to copper ferro cyanide. After the mordanting of the image is completed the plate is immersed in a solution of, a basic aniline dye of the proper red or orange color. As is well known, the action of the mordanting bath is to affect the image in such manner that it will absorb the dye according to the density of the image. This selective absorption of the dye will produce a picture colored. in o range-red and having the color ing matter deposited according to the den-- sity of the image and consequently in proportion to the occurrance of the color sen- .sations in the subject originally photographed as recorded by the emulsion. The coloring of the upper image may also be accomplished by means of a selectively hardening bleach. 'Any of the well known bleaches of this character will be applicable for the purpose. We have obtained reasonably satisfactory results with a bleach consisting of a mixture of two solutions, one of which (A) is composed of potassium ferri-cyanide 37 grams,- potassium bromide 56 grams, potassium bichromate 37 grams, glacial acetic acid 10 c. c., water 1000 c. c. and (B) potassium alum 5% solution, equal parts of solutions A and B are used. The action of such a solution is to selectively harden the gelatine and thereby cause the dye to be absorbed by the gela tine in inverse ratio to the quantity of silver present in the image. It Wlll. he

noted that when this method is employed photographed is transparent while that portion recording the white of the original object bears an image in both layers of the emulsions, that is, black and white on the negative are reversed. Similarly the orange-red of theobject photographed appears blue-green on the negative and is recorded in the lower layer, while the bluegrecn of the.original objectappears as an. orange-red image in the negative and is recorded in the upper layer. If this method of coloring the image on the negative is employed it will alsobe necessary to employ a similar method when printing'the positive in order that the colors in'the resulting positive may be correctly represented.

It is to be noted that the colors on the negative are reversed, that is the" image formed in the lower layer, which "was origi. nallysensitized to the orange-red of the spectrum, has been colored blue-green while the upper layer, originally sensitized to record blue-green values, has been colored orange-red. The negative plate is complete and presents two images in a pure and transparent condition, with the colors incorporated properly throughout. The plate is essentially a negative. Thus blaclt in the subject photographed appears white on the plate, and likewise white appears black. This reversal of the white and black values in each of the superimposed images is in addition to the interchanging of the orange-red and blue-green in the respective layers of emulsion.

' A similar process is employed in print ing the positive. ,The plate of film which is to receive the positive is similar-in all respects to the negative: plate before exposure and bears the same kind of emulsions arranged in the same manner upon the transparent support. The positive is exposed once, and after exposure is treated in a manner in all respects similar to the process employed in producing the color negative. It will be noted that the colors must again be reversed in the printing of the positive in order that correct representations will be obtained in the finished picture. The finished positive is illustrated in Figure 8 and by comparison of this figure with Figure 7 which shows. the completed negative, it will be seen that a reversal of color values is effected in the printing of the positive. The negative thus bears color values reversed with respect to the occurrence of colors in the ob ect photographed The finished negative" is illustrated in Figure 7. The portion of, the film recording the black of the ob ect the colors on the color negative. and again and the finished positive bears color values reversed with respect to the occurrence of the colors in the negative, The result is that the finished positive is a true representation of the object photographed. I

The reversal of the colors in forming the negative. and the second reversal of the colors in forming the positive has several advantages probably the most notable of which is that the color reversal serves to compensate for any inherent discrepancy of internal contrast in slow and fast emulsions. The layer of emulsion nearest the film must, of course, be a fast emulsion, while the upper layer, which is directly exposed to the light must be slower in order that a complete ex- .posure of both emulsions can be obtained in the same length of time. By interchanging reversing them during the printing of the positive the possibility of undesirable results which might occur were one color carried throughout in a single emulsion are avoided.

In our co-pending application mentioned above we describe a method of producing a photograph in three colors by employing a film bearing three emulsions sensitized respectively to different colors. For instance, the lower or first 'coating might be red sensitive, the middle coating green sensitive, and the upperficoating blue sensitive, and having incorporated it in a quantity of yellow dye in the same manner that such dye is incorporated into the upper emulsion as described in this application. We prefer, however, to carry out the three color process by exposing a second ordinary plate torecord the blue sensations and make from it a yellow print in the positive to supply the third color. This yellow positivefmay be printed asa separate print or may be incorporated directly upon .the plate already bearing the positive in two colors.

Our invention also contemplates an improveinent in printing the positive from thecolor negative by means of which improvement we secure a better distinction and a more vigorous coloring of the positive. To accomplish this we employ a dichroic filter having transmission bands at the extreme ends of the spectrum to accentuate the color separation of the negative. thus coloring the light used for printing the positive we have found that a very good rendition of colors is obtained on the positive even when'the colors of the negative are not of exceptional purity.

'It is to be understood that with our improved process there is no possibility of a color fringe occurring in the picture inasmuch as the various images are exactly su-.

. qperimposed. Likewise the requisite manipu- -lation is simplified in that the development of the plurality of superimposed images is by the other image.

our invention, but it is to be understood that certain modifications, such as varying the exact nature of the different developing and. toning solutions employed, and the like, ma be made within the'full scope of the appen ed. claims, and it is also to beunderstood that the plate or film used in the specification'and claims is not intended to refer to any particular type of photographic film, plate or the like, but is to be understood to mean any suitable support bearing'a sensitized medium which may be used as a sensitive element in the production of the pictures.

Claims. 1. A method of producing a color photograph comprising forming in layers of emulsion sensitized respectively to. record difi'erent color values, a plurality of superimposed latent images of different color sensations, developing said latent images and coloring the images thus developed respectively, in colors other than those whose values are recorded in the said respective images.

2. A method of producing a color photograph comprising forming in layers of emulsion sensitized respectively to record different color values, a plurality of superimposed latent images of difi'erent color sensations, developing said latent images and coloring each of the respective images thus developed with a color whose values are recorded by another of said images.

3. The method of producing a color photograph in two colors comprising forming in layers of emulsion sensitized respectivelyto record different color values and combined to constitute a substantially unitary body, two superimposed latent images of different color sensations, simultaneously tively to record different color values, two,

superimposed latent images of differ nt color sensations, simultaneously develop ng and then fixin' said two images, bleach ng both images, t on re-developing the upper image and then coloring each of said images with that color whose values are recorded 5. The method of producing a color photograph in two colors comprising forming in layers of emulsion provided on one side of a single support to constitute a substantially unitary body and sensitized respectively to record difierent color values, two superimposed latent images of different color sensations, simultaneously developing and then fixing said two images, bleaching both images, redeveloping the upper image and then coloring the negative by first coloring the lower image and then mordanting and coloring the upper image.

6. The method of producing a color photograph in two colors comprising forming in layers of emulsion sensitized to record different color values and combined to form a substantially unitary body of Sensitized media, two superimposed latent images of different color sensations, simultaneously developing and then fixing said two images, bleaching both images, redeveloping the upper image and then coloring the negative by first coloring the lower image with a color for which the upper portion of the said medium was originally sensitized, then mordanting the upper image and then coloring the upper image with that color for which the lower portion of the said medium was originally sensitized.

7 The method of producing a color photograph in two colors comprising forming in layers of emulsion sensitized to record different color values and combined to form a substantially unitary body, two superimposed latent images of different '()l0I sensations, simultaneously developing and then fixing said two images, bleaching both images, then redeveloping the'upper image and then .coloring the negative by first chemically toning the lower image and then by dye-toning the. upper image.

8. The method of producing a color photograph comprising forming at a single exposure in layers of emulsion sensitized to record respectively different color values and combined to form asubstantial unitary body of sensitized medium, a plurality of superimposed images, the upper image recording the blue-green sensations of the subect photographed and the lower image recording the orange-red sensations, simultaneously developing and then fixing the two images, bleaching both images to thereby convert both images into silver ferrocyanide, redeveloping the upper image and then coloring the .lower image blue-green and niordanting and coloring the upper image orange-red to form a color negative.

9. The method of producing a color photograph comprising forming in layers of emulsion sensitized respectively to record different color values, a plurality of superimposed latent images of difierent color sensations, developing said latent images, bleaching both images, redeveloping the upper image and coloring each image with that color whose values are recorded in the other image, thereby forming a color negative,

printing from said color negative, in layers of emulsion sensitized respectively to record different color values, a positive having similar superimposed images recording different, color sensations, developing the images recorded by said positive, bleaching said developed images, redeveloping one of said images and coloring the respective images on the said positive also in reversed colors.

10. The method 7 of producing a color photograph in two colors comprising forming in layers of emulsion sensitized to record different color values and combined to form a substantially unitary body of sensitized medium two superimposed latent images, simultaneously developing and then fixing said two images, bleaching both images and then redeveloping the upper image, coloring the lower image, coloring the upper image in that C0101. for which the lower image bearing strata of said medium was sensitized by relatively hardening with an appropriate bath the gelatine containing the said upper image in proportion to the density of the image, then treating the plate with a suitable dye solution whereby the dye will be absorbed in inverseratio to the quantity'of silver present in the upper image to thus form a color negative.

11. The. method of producing a .color photograph comprising forming in suitably sensitized media a plurality of superim posed latent images of difi'erent color sensations, developing said images an'd coloring each image with that color whose values are recorded in the other image thereby forming a color negative, printing a positive from said color negative with light passing through a dichroic filter tothereby separate bands of color transmission corresponding to the colors of the two images, the image constituting said positive being recorded in layers of emulsion sensitized respectively to record diiferent color values.

12. The method of producing a color photograph in two colors comprising forming in layers of emulsion sensitized respec tively to record different color values two superimposed latent images of difierent color sensations, simultaneously developing and then fixing said two images, bleaching both images, redeveloping the upper image, then coloring each of said images with that color whose values are recorded by the other image, producing a second ordinary plate to record the blue sensations in the subject photographed and forming therefrom in the positive a yellow image.

13.- The method of producing a color photograph comprising forming in layers of emulsion sensitized respectively to record difierent color values and combined to form a substantial unitary body of sensitized medium at a single exposure a plurality of superimposed images, the upper image recording the blue-green sensations of the subject photographed and the lower image recording the orange-red sensations, simultaneously developing and then fixing the two images, bleaching both images, redeveloping the upper image and then coloring the lower image blue-green and mordanting and coloring the upper image orange-red to form a color negative.

14. A method of color photography comprising forming a plurality of superimposed images of different color sensations in layers of emulsion sensitized respectively to re- In testimony whereof We aflix our signa- 20 tures.

LEOPOLD D. MANNES. LEOPOLD GODOWSKY, J 11.

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