US2173490A - Method of tone-and-color synthesis in color photography - Google Patents

Description

F. G; YANES Sept. 19, 1939.

METHOD OF TONE-AND-COLOR SYNTHESIS IN COLOR PHOTOGRAPHY 2 Sheets-Sheet 1 Filed March 30, 1938 W w JJ w w Y IL 2 m J F F M M ,l; uncommon-Hum a a i s u u u u u m n u u u u n do u u n n n n u u n u n u u: u u u 5 fig mun -mun umnuufi w m A nnnunumnnucmnununnnu Sept. 19, 1939.

F. G. YANES METHOD OF TONEANDCOLOR SYNTHESIS IN COLOR PHOTOGRAPHY Filed March 30, 1938 2 Sheets-Sheet 2 -M .Y F I M 6 BY Y L l A \B' M 6 av Y L l A L I Fig-19 INVENTOR Patented Sept. 19, 1939 PATENT OFFICE METHOD OF TONE-AND-COLOR SYNTHESIS IN COLOR PHOTOGRAPHY Francisco G. Yanes, New York, N. Y.

Application March 30, 1938, Serial No. 199,656

9 Claims.

The invention relates to a method 01' color photography combining both the additive and subtractive synthesis for the reproduction of color and tone values, and also includes the photographic elements contributing to the new result.

In the present disclosure the invention will be presented as applied to color cinematography and in that form includes the finished film which, when run through a motion picture projection 10 apparatus, produces the new result. Besides cinematography the invention may be applied to other forms of the art.

That the additive method 01' color photography can reproduce a color subject almost above reproach is very well known. But such reproduction has not been adopted in cinematography due to complications found in the synthesis and, when the easier technique of alternating colors is considered, on account of color fringes and the unpleasant effect of bombardment. caused in the human eye by a succession of complementary color sensations.

In the subtractive method there is only one multicolored picture, but unfortunately that 25 practical result has been accomplished somewhat at the expense of quality, and hopelessly so, because it is inherent to the process that when pigmentary colors are mixed or combined a certain amount of black is produced. It looks as if the scale of grays and the color combinations could not be cast in the same mould. This deficiency is particularly noticeable in the subtractiveorange, so necessary to reproduce the color of the skin, and which is mostly rendered as an unpleasant 35 tobacco shade. And it so happens with many other important chromatic combinations.

According to the present invention the subtractive synthesis may furnish the scale of grays together with the whites and certain colors, while 40 other colors and combinations in which the presence of black is undesirable are additively produced.

In the drawings:

Fig. 1 shows the broad outline of the new method.

Fig. 2 illustrates as example how the subtractive and additive synthesis are combined'in the invention.

Fig. 3 is a transversal setting of pairs of pic tures in' a cinematographic film produced in accordance to the method.

Fig 4 is the synthesis obtainable with the film ing a preferred type of the finished cinematographic film.

Fig. 6 illustrates one form of the combined synthesis produced with the film in Fig. 5.

' Fig. 7 presents another form of the same synthesis.

Fig. 8 shows the invention as practiced in three color separation.

Fig. 9 shows the method in two color separation.

The chart in Fig. 1, is a clear and broad pre sentation of the method of my invention. The squares A, B, represent two bicolor subtractive pictures of the same subject, each formed by a difierent pair of complementary pigments, their subtractive character being indicated by the minus sign within the squares; the connecting lines and the plus sign within the other square showing that the final picture C is an additive combination of the subtractive pictures A and B. If we write: (A+B) =0, the binomial is the new method and the other term the improved result.

Fig. 2 is an example showing the substance of the invention. I may first produce one pair of complementary color value negatives M, G, respectively representing minus magenta and minus green; from these I obtain and properly color the corresponding positives M, G, which I combine by superimposing them in register on a transparent support thus forming a two-color subtractive picture A. Then I may produce an-- other pair of negatives -Y, BV, representing another pair of complementary, minus yellow and minus blue-violet; from these I produce two positives Y, BV, which I color and assemble to form another two-color subtractive picture B. And finally, instead of assembling and superimposing the pictures A and B according to the subtractive method, I combine them additively, as for instance, by throwing them in register by projection on a white screen, thus obtaining the final image C.

As it may be observed, each of the elements A and B in the above combination is substantially a separate and complete picture. In both of them the whites are already formed, and so are the grays and blacks; the greens and magentas, yellows, and blue-violets, both pure or mixed with white or gray, are equally and respectively present in the two pictures; and, when the additive part of the synthesis takes place, other colors and important mixtures are produced without any additional formation of black. Furthermore, in dark shades, the small excess of the predominant color which, in subtractive synthesis, would be buried and lost in a black patch, will mix now with the black on the screen, which is not a pigment and will permit any color radiation, no matter how faint, to show and contribute to the b general balance of the reproduction.

The described method, of course, is not limited to any particular form or" the art; nor are the four colors adopted in the example the only pairs of complementary ones which could be used. The

to analysis may also be limited to three or even twocolor separation negatives, as it will be later explained. In regard to working details color selec-= tion negatives may be produced in many ways, either separately, or in pairs, or even assembled 15 in a multilayer film; and so the positives may be produced, separately or together, by printing or by reversal, and processed to fix colors already present in the emulsion, or develop to leave sec= ondary color images, or treated to fix dyes or pig- Zil rnents produced in chemical reactions, or obtained by bleaching, by color migration or by discharge, or by any other suitable means. he to the additive part of the synthesis, there are besides projection, several manners of obtaining it, as for Zdjnstance in the chromoscope and other optical arrangements.

In carrying out the invention for color cinematography I may follow different lines of work 01'' which I shall present some examples.

According to one of the ways I may produce several sets of the two differently colored subtractive pictures, each set representing the same phase of the movement; place the two pictures of each set side by side on a double width film; and

35 run the perforated strip through a projector of greater speed; and project them on the screen in rapid succession as to cause the additive synthesis to be performed on the retina.

According to another manner I may combine both of the above arrangements by producing as in the the first case several sets of the two differently colored subtractive pictures, each set representing the same phase of the-movement; but instead of placing the two pictures of each set side by side in a double width film, Iput them in contiguous succession on a single width cinematographic film as in the second case. This film may be run either through a vertical double lens projector or equivalent apparatus passing two pictures at a time, or through a standard machine running ata double speed, the additive part of the synthesis being produced either on the screen or on the retina according to the system of projection adopted.

When following the first course I may simultaneously take the four negatives in separate films or in two pairs, preferably from the same point of view through one lens in combination with a suitable optical device. The described simultaneous exposure has the advantages that the four negatives record the same phase of the movement,

that cameras and projectors can be run at normal speed and that the additive part of the synthesis will be performed on the screen. I may arrange the sets of subtractive pictures on one face of a double width film or I may combine them upon arran e its two sides as in the double coated one illustrated in Fig. 3, where a transversal setting shows the support 8 carrying on one side the magenta and yellow part images, and on the other side, respectively in registration, the green andblueviolet ones. In Fig. is graphically explained how the combined synthesis is realized in this form or the method, the squares representing the positive part images, the letters the colors, the minus and plus signs the different synthesis, the single alignment the simultaneous projection and the numbers the phases of the movement represented by the pictures.

When adopting the second line of word: I may take the four negatives in two successive ex posures, corresponding to two successive phases of the movement. As the new method requires the production of two bicolor subtractive pictures, each having an independent scale of grays, it is evident that each pair of complementary negatives must record the same phase of the movement; but it is not indispensable that both pairs should simultaneously do so, because, same as in two color-additive cinematography, the pictures may be taken and projected at a greater speed, with the advantage in our case that the whites and grays are already produced and the effect of bombardment is absent. Other advantages of this way of working consist in eliminating any problem of registration on the screen, always present when the plural lantern system or similar arrangements are utilized; the even illumination of the two pictures oiTers no difficulties; and the adjustment of speed that cameras and projectors may require is a minor question in the face of the improvements which can be attained. In carrying out this form I may arrange the subtractive pictures in alternating succession on the same side of a standard motion picture film, or use a double coated one as illustrated in Fig. 5, where a longitudinal setting shows the transparent support S, carrying on one side the magenta and the yellow part images, and on the other side and respectively in registration the green and blue-violet ones. By successive projection of the pictures on a screen, the additive part of the synthesis takes place on the retina. The combined synthesis in this case is graphically described in Fig. 6, where the squares represent the positive part images, the letters the colors; the minus and plus signs the difierent synthesis; the double alignment the two successive projections, and the numbers the two different phases of the movement that have been recorded.

When I practice the third manner of working I may simultaneously take the four negatives in such way that when producing the pictures on a single width film one picture of each set of two will follow the other, in the same chromatic arrangement shown in Fig. 5, but with the condition that the two successive pictures of each set represent the same phase of the movement. In Fig. 7, is illustrated the synthesis then obtained which is different from the one shown in Fig. 6, in that the numbers indicate the same phase of the movement in the four part images. That film, as explained, has the advantage that it may be run in two different kinds of apparatus for simultaneous or successive projection. It has also the superiority that as the two pictures of each set record the same phase of the movement, when the successive movements appear on the screen the chromatic synthesis has been already completed as in Fig. 7, and there is not the least possibility of color fringes in fast moving subjects.

iii

For actually producing the four color part images, both negative and positive, I may use different optical devices, photographic material or technique according to the line of work adopted. In regard to the photographic cameras and projectors it will be unnecessary to describe optical and mechanical arrangements well known in the art for many years and some of which were specially favored when additive cinematography was in vogue. These apparatus include the plural lens cameras, mirror and prism combinations, semidialyte systems, alternating filter mechanisms, and other contrivances proposed and used for taking simultaneous or alternating exposures of selective color sensations; also the mechanical schemes in motion cameras and projectors for mbving plural picture spaces at each time or running them at a greater speed. As far as the photographic material is concerned I may use with more or less advantage some special films of the prior art; or give the standardized types some suitable treatments to create or destroy a particular color sensitivity; or I may prefer the use of sensitive material of the kind commonly found in the market, of widely known qualities and processing, and for that reason more suitable for the present disclosure. As to the technique it will require some variations which I shall presently specify.

It has been proposed for taking the four simultaneous negatives in subtractive systems a sort of bi-pack arrangement, carrying two filters in front and two filters between the elements, these having different color sensitivity. It seems, however, that only two filters should be used, either in front or between the elements, because outside of the different color sensitivity of the two elements in which the bi-pack is based in combination with one intermediate filter, it is not possible to produce complementary negatives when a selective filter is put in front of two assembled films, outside of course of compensating filters to modify the conditions of the illuminant and which have nothing to do with the separation. The obvious reason is that a filter cannot absorb a given color light for the front element and then allow that same color light to register in the rear element no matter what might be the color of the filter or the special sensitivity of th elements. So I may use to produce the four negatives in two pairs simultaneously exposed the old bi-pack or rather two different bi-packs of a type which will be later described. I may also use another form of material which is still simpler and consists of an orthochromatic film of the usual sensitivity and a panchromatic one of balanced speed assembled face to face in optical contact but without any filter between the elements, which is-favorable for better definition. In this arrangement the color selection is produced by a pair of different front filters, one magenta and the other yellow. It is true that in this case the two negatives of each pair are not complementary, but when the exposure is simultaneous and the same phase of the movement is recorded in the four negatives, they can be shifted or used in alternating operations for the printing of the positives. The simplified material is most suitable for the first line of work because the same phase of the movement is present in the four negatives and these consist of four separate series. The complementary can be paired and printed on a double width film as in Fig. 3. As to the filters they may be respectlvely placed on two lenses, at the exposure gates,

or run together with the film on a perforated support which may be the same support of the front film, all depending whether the pictures are taken from the same point of view or not and whether it is desired to use the common stock found in the market.

For the second line of work the simplified material above referred to is not suitable because a selective filter before a single pair of films cannot produce a pair of complementary negatives in each exposure and, as long as each pair record a different phase of the movement, there is not the possibility of shifting the negatives for the printing. In this case I may use the old bipack, formed by a front element in which the emulsion is of alternating sensitivity to blueviolet for one picture and to blue-violet and red for the next, in combination with alternating intermediate filters dyed on the surface of either elementcorrespondingly yellow and green. One manner I may use for producing this material is to obtain by wash-off a full surface printing relief in which every other picture space has been eliminated and apply, in different operations, to an ordinary blue-violet sensitive front film the red sensitizer, and to the emulsion of either one of the elements two printings of alternating yellow and green dyes upon a previous coating of gelatine. I may prefer, however, instead of this elaborate bi-pack to take the negatives of each pair separately, by splitting the image in known manner and using a special material which I have devised for the purpose. In this material, comprising-a pair of orthochromatic and panchromatiq films of balanced speed, which are used in combination but not assembled together, the support is provided in both with alternating colored bands magenta and yellow, said bands arranged in a transverse position perpendicular to the line of movement of the film and of a width exactly equivalent to the width of an individual picture. As only the support is dyed and this can be done before the coating with either emulsion the manufacture is greatly simplified and more precise. The films are exposed through the support and so placed that when the yellow filter appears at one of the exposure gates the magenta is at the other, and so each exposure furnishes a pairof complementary negatives recording the same phase of the movement. In this individual exposure the emulsions may be panchromatic in both films, which facilitates the balance of the contrast in the negatives, and the filters four instead of two. For the second line of work, I may also use for individual exposure of two regular films, a turning device of well known type, or similar mechanism, to alternate the filters at each exposure gate.

For the third line of work, I may take the four negatives simultaneously on two successive spaces of a single width pair of assembled sensitive films, by optical means already mentioned, and u the simplified bi-pack, and the magenta and yellow filters above described. I may use for the purpose a camera moving two spaces each time,

and according to the type adopted, I may fix,

the filters permanently on the two lenses, at the exposure gates or alternating on the support of the front element. Still in this way of working, as front selective filters are used before two assembled films, the opposite negatives are not complementary; but as the four record the same phase of the movement, one of the strips can be cessive operations. As already pointed out the finished film thus obtained may be run through two different types of projectors and is free of both additive and subtractive synthesis objections.

In Fig. 8, a simpler form of practicing the invention is illustrated in which the two subtractive pictures are made from three color separation negatives M, Y, BG, and the G and RV positives both printed from the minus bluegreen negative. When assembling the pair MG to form the subtractive picture A, the pigmentary blacks which will be formed correspond in this case to the scale of grays and the blues common to the magenta and the blue-green color values, now colored green; and when assembling the pair Y-BV to form the subtractive picture B, the pigmentary blacks formed will correspond to the grays and the greens common to the yellow part image and the blue-green part image now colored blue. In such conditions, the colors which are duplicated when four color separation negatives are taken and which are balanced by a formation of white light when the additive part of the synthesis takes place, will be now already eliminated in the subtractive part of the synthesis by the formation of black. The result then is that with three color separation negatives not only the whites of both pictures are not produced by mixture of complementary color lights, but even the formation of additional white light is prevented and naturally the effect of bombardment is further removed, the additive part of the synthesis being reduced to mixtures corresponding to colors which are not complementary.

Whichever be the line of work adopted, the three color separation presents the advantage that the material, the technique and the apparatus are extremely simplified. Considering the second line. of work, for instance, a standard motion picture camera, susceptible of accommodating a bi-pack, adjusted for a double speed and provided in the front of the lens with a turning device of known type, which will alternately present a yellow and a magenta filter for successive exposures, is all that is necessary. For the first and third way of working I may require a special camera fulfilling conditions already described and the two filters may be fixed at the exposure gates or at another suitable place. In regard to the material, the bi-pack will do. I may use the bi-pack found in the market or I may prefer one in which the filter between the elements instead of being red-orange is red, and this bi-pack will produce in the front element through the alternating yellow and magenta filters series of alternating minus magenta and minus yellow negatives, while the back element will register a series of minus blue-green negatives of substantially the same color value. When better definition than bi-packs is desired, I may split the image and have the two films separately exposed, one through a fixed red filter at the corresponding exposure gate and the other through changing magenta and yellow filters before the lens. As to the printing of the positives there will not be any problem and the coloring will be performed in the same alternating form, one picture by ma and reen pigments and the following or adjacent one by yellow and blue violet. The films may have the chromatic arrangement illustrated in Figs. 3 or 5, and the synthesis will be performed in the respective cases as charted in Figs. 4, 6 and 7.

araaaco In Fig. 9, still another form of practicing the invention is charted in which the two subtractive pictures are made from two-color separation negatives minus red-orange and minus bluegreen, each of the two RO, and BG negatives furnishing in two degrees of contrast the magenta-yellow M, Y, and the green-blue-violet G, BV, pairs of positives respectively. Although the results in this case can only be considered as approximated, the color values are so near to the four color separation that the final picture is very acceptacle. The outfit is still simpler because it is not necessary to provide the camera with alternating filters and in regard to the material the ordinary red-orange and blue-green bi-pack of the commerce is what I may use for taking the pictures. That material furnishes two strips respectively carrying series of negatives of average contrast which I may print to produce alternating or adjacent pictures of different contrast, giving the magenta and green coloring to one picture of each set and the yellow and blue-violet to the other one, as it will be later explained. The films may have the chromatic arrangement illustrated in Fig. 3 or 5 and the synthesis will be performed as charted in Figs. 4, 6 and '7 according to the line of work which is adapted.

It must be understood that the sensitivity and color filters mentioned when describing the dif- -separation including a duplicate minus bluegreen negative does not present any problem as explained.

When series of images of alternating diiferent contrast are required from the same negative strip I may use the known positive material hav ing in the emulsion the usual orange screening dye in combination with a violet filter alternating in the path of the printing light with a compensating neutral filter or slightly colored one. I may also use for the same purpose series of said alternating filters dyed on a perforated transparent strip, which can be the same support of the material when the positives are separately printed for some given purpose of the final processing.

The coloring of the positive part images which may be produced by different systems presents the question of alternating the pairs of complementary pigments for each subtractive picture. This problem is naturally different according to the special material which could be used. But for common stock and assuming that all the images are firstly mordanted by any well known treatment, the corresponding alternating colors can be mechanically applied in many forms. I may use, for instance, a full surface gelatine relief produced by wash-oif in which every other picture has been eliminated, immerse the strip in the dye solution, apply the respective coloring by contact and finally discharge or wash away the excess of the dye. In regard to the coloring, when the optical system or the relative position of opposite films cause the complementary negatives to appear in the same direction, one series of positive part images may be printed, mordanted and colored and the other added by imbibition.

In the last mentioned case, I may prefer'to produce the imbibition coloring in another form upon one side of the single coated film. First, I may combine and assemble the two complementary series of negatives and print from them two black and white positive strips, each carrying the blacks and grays of all the images. Second I may submit one of the positive strips to a hardening or other treatment to make it suitable for imbibition printing. Third, I may combine the otherpositive strip with each of the ones carrying the color value negatives in order to eliminate the part corresponding to the black and grays, and so I may obtain wash-01f reliefs which will exclusively print the colors. And fourth, I may print those colors in succession upon the first black and white positive strip and so I may produce the chromatic arrangement,

of either one of the films illustrated in Fig. 3 and Fig. 5. Although somewhat more complicated that technique. will favor the sharpness of the drawing and the gray tones usually unsatisfactory in imbibition. The results are equivalent to the subtractive pictures formerly described, as the silver images represent the same grays that the complementary pigments would have produced if fully printed part images of the original negatives had been combined.

When the first part of the method has been accomplished, comprising the production of two subtractive pictures formed by two different pairs of complementary pigments on a cinematographic transparent film, the final step is to produce the additive combination of said pictures. As we have seen, this is accomplished by throwing the pictures in register on the screen by simultaneous projection in the first line of work, by successive projection in the second and by either one in the third manner of applying the method.

From the above the improvements may be judged which have been apported to the art by eliminating, in a combination of the two classic methods, known objections to both, the additive and subtractive synthesis. In respect to the first, color fringes and bombardment have been removed; regarding the second, pigmentary mixtures have beendimited to produce grays and blacks only where light is absent and not where colors appear mixed in the subject; and as far as the combination is concerned, the new result represents another step in cinematography towards the desideratum of a perfect color reproduction.

After having described to the best of my knowledge the new method I wish to be understood that the present disclosure is for the purpose of illustration only and that my invention includes any equivalents or variations which fall within the scope of the appended claims,

Regarding terms used in the following claims, I wish to point out that the word picture has been adopted to represent a finished photographic record of positive character in which whites, grays, blacks and colors are present and materialized. The word image has been preferred to express the optical likeness of a picture, as the result of its projection on the screen. In regard to colors, when "magen and "yellow" are mentioned as such, they express the known combinations of the primary forming those secondary. Although the above definitions correspond to some of the meanings of the words referred to it has been thought convenient to affirm them for the sake of a clear understanding.

I claim:

1. A cinematographic film suitable for projection carrying four color separation positive part images of subtractive character provided with their corresponding pigments and representing the same subject, said part images so arranged in said film that one picture space shows a green and a magenta colored part images in register while the adjacent picture space shows a yellow and a blue violet colored part images in register, and so in successive picture spaces of said film.

2. A cinematographic film suitable for projection carrying four positive part images of subtractive character provided with their corresponding pigments in two pairs of complementary different colors to provide four images in four difierent colors and representing the same subject, said part images so arranged in said film that one picture space shows two complementary colored part images in register while the adjacent picture space shows two other complementary colored part images in register, and so in successive pictures spaces of said film.

3. In color cinematography, a combined method of subtractive and additive synthesis which consists in producing first a cinematographic film carrying four positive part images of subtractive character provided with their corresponding pigments and representing the same subject, said part images sufllcient for a full color reproduction of the subject and so arranged in said film that one picture space shows one pair of complementary colored part images in register while the adjacent picture space shows another pair of complementary difierently colored part images in register, and so in successive pictures spaces of said film, each of said pairs of complementary colored part images in register representing a two color subtractive synthesis furnishing whites, grays, blacks and other known bicolor'values in each picture space; and then projecting said film on a screen so that by means known in cinematography the composite chromatic element present in one picture space and the one present in the adjacent will produce on the same place of the screen, respectively, two

images having a diiierent chromatic composition and which will combine additively and complete the four color synthesis.

4. A cinematographic film suitable for projection carrying in one picture space two positive part images of subtractive character in register and respectively representing magenta and bluegreen color values, and in the adjacent picture space two other positive part images of subtrac tive character in register and respectively representing yellow and blue-green color values, all of said part images representing the same subject, said four part images corresponding to positives printed from three color separation negatives including a duplicate of the blue-green part image to complete the number of four; the non duplicated part images colored according to the subtractive method magenta and yellow and the blue-green duplicated part images colored green in one of the picture spaces and blue-violet in the other, so thatin each of the picture spaces two part images colored with two complementary pigments are respectively combined.

5. A cinematographic film suitable for projection carrying in one picture space two positive part images of subtractive character in register and respectively colored with two complementary pigments, and in the adjacent picture space two other positive part images of subtractive character in register and respectively colored with two other and different complementary pigments, so that in two adjacent picture spaces four part images in four different colors are distributed, all of said part images representing the same subject; said four part images having values cor responding to positives printed from three color separation negatives, one of the part images being duplicated to complete the number of four; each one of the two non duplicated part images respectively combined with one of the duplicates in one of the picture spaces, the non duplicated. part image colored according to the subtractive method 'and the duplicate with a complementary pigment,

6. A' cinematographic film suitable for projection carrying in one picture space two positive part images of subtractive characterin register and respectively representing red-orange and blue-green color values, and in the adjacent picture space two other positive part images of subtractive character in register and also representing red-orange and blue-green color values respectively, all of said part images representing the same subject, said four part images corre-- sponding to duplicates printed in different contrast from two color separation negatives, the red-orange duplicated part images colored magenta and yellow andthe blue-green duplicated part images colored green and blue-violet respectively, said colored part images arranged in complementary pairs 50 that the magenta and green colored part images are combined in one picture space and the yellow and blue-violet colored ones in the adjacent picture space.

7. A cinematographicfllm suitable for projection showing in'one picture space two positive part images of subtractive character in register and respectively colored with two complementary pigments, and in the adjacent picture space two other positive part images of substractive character in register and respectively colored with two other and different complementary pigments, so

airaaoo that in two adjacent picture spaces four part images in four difierent colors are distributed, all of said part images representing the same subject, said four part images having values corresponding to positives printed from two color separation negatives, each of the two part images duplicated to complete the number of tour, and each pair of part images of common color values respectively colored with two difierent pigments which combined represent the color corresponding to their common values, the two difierent pigments coloring one pair of duplicated part images respectively complementary to the pigments coloring the other pair.

8. A cinematographic film suitable for projection carrying in one picture space two positive part images of subtractive character in register and respectively colored with two complementary pigments, and in the adjacent picture space two other positive part images of subtractive character respectively colored with two other and different complementary pigments, so that in two adjacent picture spaces four part images in four different colors are distributed, all of said part images representing the same subject, said fourpart images having values corresponding to positives printed from color separation negatives and colors in relation with said values.

9. The method of producing a multicolor image which consists in producing from color separation negatives four positive part images of subtractive character, coloring said part images in relation with their respective color values with four difierent pigments including two difierent pair \of complementary ones; forming in a supporting area with two 01' the part images colored with complementary pigments a bicolor subtractive picture, and in another supporting area with the other two part images colored with two other and different complementary pigments a second and separate subtractive bicolor picture; producing by known optical means two images one from each of said bicolor pictures upon a viewing surface; and bringing the images of said bicolor pictures into register upon said viewing surface to form a composite and final multicolor picture. I

I FRANCISCO G. YANES.

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