US2005970A - Color photography - Google Patents

Description

June 25, 1935.

FIG-/ Filed Nov. 30, 1931 2 Sheets-Sheet 1 BLACK OBJECT WHITE FIG-2 u 2 Q 3 a:

m w i! BLUE GREEN YELLOW RED 0 L 0 L 0 L 0 L CLEAR CLEAR WHITE CLEAR BLAGK 4 CLEAR RED YELLOW RED D L D L D C I CLEAR BLUE BLUE OLE/4R CLEAR BLACK COLORS OF FIN/SHED NEGA TIVEBY TRANSM/TZ'ED LIGHT BLUE L W RED BLUE GREEN VELLO L D L D L D L D INVENTOR.

A TTORNE YS.

NEG/1 TIVE June 25, 1935. L. M. DIETERICH 2,005,970

COLOR PHOTOGRAPHY Filed Nov. 30, 1951 2 Sheets-Sheet 2 WHITE BLA CK BLUE GREEN YELLOW RED L D L D L D L D BLACK CLEAR GRAY GRAY CLEAR CLEAR BLUE CLEAR BLUE BLUE CLEAR CL54R v YELLOW kELLow 0 L 0 L BLACK WHITE BLUE GREEN YELLOW RED 0 y L 0 L 0 L 0 L k a o: (L

COLORS 0F F/N/SHED PR/NT B) T/MNSM/TTED LIGHT INVENTOR. Luz/W47 M fl/efer/cfi A TTORNE YS.

Patented June 25, 1935 PATENT OFFICE COLOR PHOTOGRAPHY Ludwig M. Dieterich, Los Angeles, Calif., assignor to Detracolor Ltd., a corporation of Nevada Application November 30, 1931, Serial No. 578,059

(01.95-2) This invention relates to color photography in accurate predetermination of these values (subgeneral; and more particularly to the production of photographic plates or films and emulsions;

and to a process whereby the desired color effects 5 are produced.

it possible to produce more accurate and heretofore unobtainable color efiects, and at the same time more economically than present color 1 photography methods.

Another object oi-this invention is to provide, mr color photography, identical or similar emulsions in single or double coated stock for both negatives and positives, thereby greatly increasing the simplicity of processing and decreasing the cost of the raw stock and its processing.

Still another object of this invention is to obviate the necessity of any changes,special designs, attachments or accessories relating to standard cameras, magazines or projection machines, such as now used for black and white photography, for adapting them to color work.

Another object of this invention is to secure a coloring agents.

Another object of this invention is to eliminate all possibilities of human errors or faulty judgment in the selection and application of colors or tones during the processing of the respective light sensitive emulsions. Another object of this invention is to impregnate one or more light sensitive emulsions during their manufacture. with dyes or coloring agents not of the complementary but of the same 1 color values to which they are sensitized.

Another object of this invention is to eliminate all special mechanical or physical apparatus or methods to secure perfect registration of the images of the respective emulsions both for the negatives and their prints.

Another object of this invention is to provide a photographic color process which is equally advantageously applicable to portrait photography, lantern slides, and all types of transparencies; as

the need for the exercise or individual judgment on the part of the manipulator of the stock after exposure, for determining the proper relative color values; and instead,-to substitute tor-such exercise of judgment, a definite and substantially the prior art. One of the objects of this invention is to make rigorous four color separation employing but two ject only to the exposure values) during the manufacture. Thus the color determinations are under exact control, which is not possible by practicing 5 It is still another object of this invention to obviate the necessity for any special lighting or other exposure conditions over those normally used 'in black and white photography, but which are now necessary when using substantially any 0 of the present commercial color processes,

Another object 01 this invention is to reduce the danger of halation which now exists in prior methods, that utilize a series of single layer emulsions.

Another object of the invention is to provide a multiple layer emulsion of the sensitive medium for color work, in which the emulsions have overlapping ranges of sensitivity along the spectrum, but at the same time, the combined emulsion is sensitive to the whole range of colors in the spectrum.

The films used under this invention are preferably oi the single coating, multiple emulsions type for either the negative or the positive. 25

The processing consists of a novel combination of steps well known in their physical and chemical aspects and results.

In order to describe accurately how this invention may be practiced, a brief review of the ordinary photographic process is helpiul. In photography the light sensitive medium is usually an emulsion of a silver halide. This emulsion is usually supported on a baseor stock. Upon exposure the sensitive medium is affected approximately in proportion to the light intensity and to the length or exposure. The emulsion can then be developed to cause that portion of the silver salt which had been affected during exposure to be reduced to metallic silver. The unaffected or unexposed silver salts are not reduced to metallic 'silver but may be entirely removed by the process stood that further description is unnecessary. It

' applies as well to the making of positives as to the making of negatives.

In color photography the problem is to change the black and white values obtained by the exwhen superimposed, produce the desired color effects. This is usually accomplished by first partially or completely bleaching the emulsions, and then dyeing the emulsions with an appropriate color so as to produce a colored transparency for each emulsion. when these emulsions are superimposed, then the resultant transparencies represent either a positive or a negative in color of the object photographed. In general this invention employs the idea of providing two or more superimposed emulsions or layers which can be treated independently of each other to secure the desired color effects.

One of the characteristics of this invention is the pre-dyeing of one of the emulsions a color corresponding to the sensitivity range of that emulsion and the coloring, either by dyeing or toning, of the other emulsion with the color of the photographed object to which it is sensitized, in contradistinction to the usual practice of using complementary colors.

My invention possesses many other advantages, and has other objects which may be made more easily apparent from a consideration of one embodiment of my invention. For this purpose I have shown a form in the drawings accompanying and forming part of the present specification. I shall now proceed to describe this form in detail, which illustrates the general principles of my invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of my invention is best defined by the appended claims.

Referring to the drawings:

Figure 1 is a cross section, greatly enlarged, of a sensitized negative or positive plate or film utilizing the invention;

Fig. 2 is a diagram showing approximately the light sensitivities of the top and bottom emulsions respectively;

Fig. 3 shows schematically the colored object to be photographed in the first band; and in successive bands the top and bottom emulsion color characteristics of the negative during processing periods; and in the lowest band, the color characteristics of the finished negative; and

Fig. 4 shows schematically the color characteristics of the finished negative in the first band and in successive bands, the top and bottom emulsion color characteristics of the positive during processing periods; and in the lowest band, the color characteristics of the finished positive.

This method and the related drawings, however, are to be considered in an illustrating but not limiting sense.

The negative film consists of a standard transparent base a on which is coated a light sensitive silver emulsion c which in manufacture is dyed or impregnated with a soluble red dye. This red is of any well known type, in which low densities transmit yellow, and high densities red. The lower graph of the spectrogram shown in Fig. 2 of such an' emulsion shows highest transmission at 6500 (Angstrom units). It cuts off towards the infra red at about 7200; includes yellow (5850) and green (5350), cutting off at about4850, at the start of the blue transmission. The ordinates of this diagram are drawn to logarithmic values, so that the sensitivity of green and yellow is proportionately much less than is indicated in the diagram.

Ontop of this emulsion or on the other side of the base, an orthochromatic emulsion b is 7 y coated, the spectrogram of which is shown in the upper graph of Fig. 2. This shows start .of

transmission at 3800 with a maximum for blue (about 4850) and a second but lesser, peak in the green region.

Under this invention the following use is made of these spectrum characteristics as diagrammatically shown in Figs. 3 and 4.

For illustration an object to be photographed is shown as a horizontal band of squares in Fig. 3, showing from left to right successively no color (black), all colors (white), blue, green, yellow and red. This object so labelled in Fig. 3 is merely a diagram. The respective areas may be very much interspersed and in fact overlapping, but I show separate oblong areas. The colored oblongs of blue, green, yellow, and red are split in half. The left hand half of each of these colored oblongs is marked with a letter D to indicate that it is a dark shade; similarly the right hand half is marked with an L to indicate that this half of each oblong has a light shade.

The raw stock or film above described is used to photograph this object. After exposure the photographic plate or film is developed, washed, fixed, washed in water and other solutions and dried, the details of which operations are hereinafter described.

Thereafter the top emulsion may be dyed blue under any well known process, such as the one hereinafter explained in detail.

The red yellow dye of 'the bottom emulsion has two functions. It acts as a filter dye in order to produce the desired spectrum characteristics for the bottom emulsion and also produces in the finished negative or positivemthe desired color values.

This can be achieved by one dye or by two dyes each producing the above stated efiects. In such a case these two dyes may be soluble in two diflferent solvents. As an example, the filter dye may be soluble in water and the dye producing the final coloring in alcohol.

The possible errors due to the human element are eliminated and the processing greatly simplified by omitting the separate coloring of the emulsions during processing. Color bleeding between the two emulsions is under this method also obviated.

An important characteristic of this form of my invention is the fact that a single processing sequence only is used for both emulsions in both negatives and positives.

An example of a preferred detail application of this invention is herewith described as applied to motion pictures. 4

Under this invention, and this preferred example, the bottom layer c (corresponding in sensitivity to "panchromatic film), consists of a silver emulsion which is impregnated with a spirit soluble dye of that class which is a yellow color in light densities and red color for heavy densities, there being a gradual or continuous change from one color to the other in accordance with the variations in density, a suitable dye for this purpose is oleate of diethyl m-aminophenol succinein.

This dye acts as a filter and coloring agent for the silver halides and is chosen or such a concentration as to impart to this emulsion a light sensitivity as shown in the lower spectro-' gram of Fig. 2.

This action may also be achieved by using a filter and an intermixed coloring dye as previously stated.

On top of this emulsion'jayer the. layer of orthochromatic emulsion 5 (corresponding in sensitivity to orthochromatic film), is placed, having the sensitivity characteristics as heretoforeexplained.

In processing the following operations may be employed:

1. After exposure the film is developed, as customary for black and while practice, in such as the customary borax developer. This reduces the exposed silver halides of the emulsion to metallic silver. f

2. The developed film is washedgfor a short time to remove substantially all of the developer. 3. The washed film is then subjected to a combined bleaching and mordanting process. For this purpose potassium ferricyanide may be used at usual concentrations; the opaque metallic silver is oxidized to a translucent silver salt (silver ferro-cyanide), which serves to mordant the red-yellow dye of the bottom emulsion.

4. The film may then be immersed in a solution of basic blue dye such as methylene blue which will mordant to the image in the outer emulsion b, but which will not affect the image in the inner emulsion.

5. The film is then given a short water wash to remove substantially all of the bleaching solution.

'6. The film is then treated with a fixing solution, such as sodium thiosulphate, or any other well known clearing agent.

'7. The film is then washed in water to remove excess fixing solution and excess blue dye.

8. The film is then washed in alcohol or other solvents, to wash away the unmordanted yellow to red dye in the inner emulsion.

9. The film is then dried.

In Fig. 3 the band or bands designated by the letter A show respectively the top emulsion 15 and the bottom emulsion c after development but before bleaching, and before the coloring of the top layer b. It is here seen that on the top emulsion b, the black oblong is clear, because over this area the emulsion was not affected and all of the silver salts can be washed away.

The white oblong is registered as black on top emulsion b since this top emulsion is sensitive to white and therefore the metallic silver was strongly deposited. The blue oblong also affected the top .emulsion b, but with reverse values, the left half of this oblong being light gray and the right half a dark gray.

The green oblong similarly affects the top emulsion b.

The top emulsion b being insensitive toyellow 'and red, these two oblongs of the object produce clear areas in this top emulsion b.

Now let us consider the lower emulsion c of the same series A. The black oblong of the object fails to register as the lower emulsion c is insensitive to black; therefore the corresponding oblong on emulsion c is clear.

The white oblong of the object registers as a darkv red because it strongly affects the lower emulsion.

Since the bottom emulsion c is not sensitive to blue, the-blue oblong of the object does not affect the lower emulsion c, and therefore it remains clear.

The green oblong of the object weakly aflects the emulsion c and therefore it shows respectively as a light and dark yellow.

The same is true of the yellow oblong.

The red oblong of the object strongly ail'ects the lower emulsion c, and is shown in reversed the white oblong of the object registers as a blue oblong on the top emulsion b. The two gray oblongs corresponding to the blue and green of the object have now been colored light blue on the left half and dark blue at the right half.

The finished negative N, is merely a superposition of two transparencies b and 0. Black is shown as clear or white by transmitted white light. The white oblong ofthe object is reproduced in the negative as black due to the superposition of the dark blue and the dark red.

The blue oblong of the object is represented as blue on the finished negative, but with reversed value, and dark blue is shown as light and the light blue is shown as dark.

The green oblong of the object is also shown as green in the negative but with reversed values. The green tint is obtained by the superposition of the blue and yellow oblongs of the series B.

The yellow and red oblongs of the object are correspondingly reversed in the negative, and are contributed solely by the lower emulsion c.

From this finished colored negative a contact print is made, using a positive film equal or similar in construction to that of the negative film, and with the following characteristics.

Upon a standard transparent base a light sensitive silver emulsion is coated, exactly or similarly dyed as the bottom emulsion of the negative.

An orthochromatic emulsion with a sensitivity similar to the orthochromatic emulsion in the negative is then coated on top of it.

A contact print is now made from the finished negative.

The processing method of the positive is exactly the same or similar as that above described V for the negative, as an example of the practical application of this invention.

The succemive steps are shown in Fig. 4.

It must be noted that all actinic records made for the blue sensitive emulsion are colored blue and the records made for the yellow-red sensitive emulsion are colored yellow-red and that the double reversal of shade from black to white through blue, green, yellow and red results in a final print or photograph as shown in the bottom band of Fig. 4.

Thus the white oblong of the negative affects both the top and bottom emulsions b and c of the series D, of Fig. 4. This series represents the top and bottom emulsions of the print after developing but before bleaching and dyeing. The white oblong ofthe negative is printed black on the top emulsion b and is printed red on the emulsion c. The black oblong of the negative does not affect either emulsion b or c and therefore the corresponding oblongs of b or c are clear.

The blue and green oblongs of the negative are shown as gray on the top emulsion of the print. On the bottom emulsion c of the print the blue does not register. The green registers as yellow with values reversed.

The yellow and red oblongs of the negative do not affect the top emulsion b and therefore the dyeing. Here the black oblong of the top emulsion B becomes blue and the corresponding gray oblongs on the top emulsion b become blue. The lower emulsion c has not altered in color values.

Due to the superposition of the two emulsions b' and c the final print is a transparency having .the color characteristics as shown in the bottom band of Fig. 4. The white oblong of the negative is printed as black. The black oblong of the negative is printed as white; The blue and green oblongs of the negative, are respectively shown as blue and green transparencies in the print with light values reversed. The green oblong of the print is due to the combination of the blue and yellow transparencies in theseries E.

The yellow and red oblongs of the negatives are contributed solely by the lower emulsion c and are therefore the same as in the .series 1E. These are the same as the oblongs of the negative but with reversed color values.

Comparing the print of Fig. 4, with :the object of Fig. 3, it is seen that the object has been faith- 1 for the two emulsions of negative and positive films can be selected with the appropriate change of dye or tone values and processing details without departing from the principal characteristics of this invention.

It thus apparent that by providing a series of contacting emulsions, separately, and selectively sensitive to difierent portions of the spectrum, I-can produce a final result that is faithful without any danger of misalinement between the varicolored layers, without the necessity of using during the processing of these emulsions any additional colors or coloring agents, and without the necessity of using any special coloring or printing machines-as are now necessary in commercially prevalent color processes, and with the use of standard cameras and projectors only. No filters need be used, although .under some circumstances it may be advisable to accentuate or delete some color values, These advantageous results are due to the ability of the sensitive medium to do two things: first, to-be selectively tially so 'as to subdue some of the color values.

I claim:

1. A method of producing photographic images in color on a film having a plurality of different light sensitive emulsions thereon one of said emulsions being predyed the color to which it is predominantly light sensitive which incldes: exposing said film to actinic light; developing the respective latent images thereby obtained; mordanting the color in the image carried by the predyed emulsion; selectively coloring another of said images the color to which the emulsion bearing said image was predominantly light sensitive;

and removing the dye from the unexposed por-' tions of said predyed emulsion.

2,. The method of producing photographic images in color on a film .havinga plurality of diner-- ent light sensitive layers thereon, one ofsaid layers being predyed the color to which it is predominately light sensitive, which includes: exposing said light sensitive layers to actinic light; developing the respective latent images thereby obtained; mordanting said images; selectively coloring the image in the undyed layer; and removing the dye from the unexposed portions of said predyed layer.

3. The method of producing photographic im-. ages in color on a film having a plurality of different light sensitive layers thereon one of said layers being predyed the color to which it is predomisaid light sensitive layers to actinic light; devel- .30. nately light sensitive, which includes: exposing oping the respective latent images thereby obtained; mordantingsaid images; dyeing the image in the undyed layer blue; fixing said images and removing the color from the unexposed portions of said predyed layer.

4. The method of producing photographic images in color on a film having a plurality of difierent light sensitive layers thereon, one of said layers being predyed the color to which it is predominately light sensitive which includes: exposing said light sensitive layer to actinic light; developing the respectivelatent images thereby obtained; mordanting the image in the predyed layer; dyeing the other image with a basic dye the color to which said layer was predominately light sensitive; and washing said film in a spirit solution to remove the excess dye in the predyed layer.

5. The method of producing photographic images in color on a film having a plurality of difierent light sensitive emulsions thereon, one of said emulsions being predyed the color to'which it is predominantly light sensitive which includes: exposing said film toactinic light; developingthe respective latent images thereby obtained; selectively coloring the image in the emulsion which is not predyed the color to which the emulsion bearing said image was predominately light sensitive; washing said film; and drying said film.

.LUDWIG M. DIETERICH.

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