US2326500A - Photographic and cinematographic multicolor images of correct color value - Google Patents

Description

Patented Aug. 10, 1943 rnoroonnrmc MULTICOLOR ,SOLOR VALUE Wilhelm Schneider and and Gustav Wilmanns,

AND CINEMATOGRAIPHIC IMAGES OF CURRECE Heinz Schulze, lllessau, Wolfen, Kreis Bitterfeld, Germany, ,assignors to General Aniline &

Film Corporation, tion of Delaware New York, ill, a corpora- No Drawing. Application March 6, 1940, Serial No. 322,482. in Germany February 23, 1939 5 Claims. This invention, relates to color photography and more particularly to the production of photographic and cinematographic multicolor images of correct color value.

It is an object of the present invention to pro vide a process for the production of multicolor images on multilayer photographic materials.

Another object is to provide a process for the production of multicolor images of correct color value on multilayer photographic material.

A still further object lies in the provision of a suitable material to carry out the process.

Still further objects will be apparent from the detailed specification following hereinafter.

This invention is based on the observation that it is generally necessary, when taking color' images, to alter the sensitization of the material according to the illumination used for exposure, for instance day-light, arc-light and nit'ra-light, since in each light source another spectral region is predominating. If the light used is different from that for which the material was sensitized,

i. e. if wrong light" is applied, it is impossible to obtain images of correct color val\ue without additional measures.

Errors in illumination for instance mayflbe eliminated by suitable filters during the exposure.

This, however, has the disadvantage that the sensitivity of the material is not fully utilized .on account ofthe longer exposure-time caused by the filter. It is therefore practical to correct the colorsonly in the printing process. Here the color correction may be accomplished in different ways, for instance by a colored printing light, a

suitable color-developer containing, if necessary,

dyestufi -components or'by dyeing the finished image itself. As proposed in our German Patent application 1.63 538 Iva/57b, filed January 18,

1939, corresponding to the U. S, Patent 2,316,291, it is especially practical, when dyeing the pic ture, to use such dyestuffs, the absorption maxima of which correspond -to those of the image dyestufis. The use of filters for the colorcorrecdon here also brings about an undesirable prolongation of the, exposure-time, not to forget,

incorrect colors.

It has been found that these disadvantages I arev dispensed with when using for the production of the colornegativ e' a multilayer photographic material of such kind, that one color predominates and that the dyestufi images of the multilayer that too strong filtering of the light often yields photographic material do not fit together as to show. a neutral black. The negaprinting material, on which the partial color pictures produced do likewise not form a neutral black, but deviate from the neutral point in such a way, that the color component, predominating in the negative,'is just compensated resulting in a neutral multicolor positive of correct color value.

' According to this invention it is for instance possible to take .pictures on the same negative material in da -light, artificial light and at different hours of the day without a filter by using the full sensitivity of the material. Without color correcting means the negative is printed onto a positive of correct color value'by using a printing material balanced correctly according to the respective negative. The invention is of special advantage in the production of color prints on paper. When the colors difier largely,

a filter besides the printing material may be,

used corresponding to-the respective negative. In this way too strong filtering and incorrect colors caused thereby'are avoided.

In carrying out the present invention a negative which, i. e. the point where all three fundamental colors of the difierent emulsion layers together show a neutral gray, is adjusted for an illumination with a light lying between arc-light and day-light. The actual illumination of the negative material is made, merely theoretical light, but either with arclight or with day-light, regardless'of the resulting false color tinge produced on the negative material. In the case of arc-light the resulting image shows blue in preponderance, wliereas in the case of day-light the resulting image is short "of blue colo'r values. Care must be taken in all events that the scantiest color is still represented in the negative to such an extent .that a positive partial picture can be'registered.

It is advisable therefore to choose the neutral point of the negative material about in the.center of all possible light sources. It is obvious that in this case the'false color tinges'will be less remarkable than point being shifted entirely to one side.

Up to now the negative just described had to be printed by means of different colored light sources and strong filtering means in order to produce a positive image of true color values on a standard positive multi-layer material of given quality. s r

According to the present invention a. plurality of diflerent printing materials material with complementary or non-complementary color is used the neutral point of however, not with this in the caseof the neutral is kept in stock and for each negative the most suitable one tive material, -which qnegative copied onto a tive material. A neutral image 01' correct color value is thus obtained.

of these diiIerent brands of printing material is chosen. The printing materials mentioned dit- Ier; from each other in the ratio in which" they I register thethree fundamental colors.

When, for instance, a negative is to'be printed which failed in fully, recording the red color values, then a positive printing material is chosen in'which the blue values prepcnderate so that the color deficiencies of both negative and positive film are contrary to one another and therefore just compensate each other so asto yield a true'color positive. The same principle is ap piied.to negatives in which yellow or purple are poorly recorded. In each case the correction of untrue colorrepresentation in the negative is effected not by colored-filters or colored lightsources, but by selecting a. printing material which as much as possible is the contrary of the negative material as to its color recording capacities. 1 1

The process oi! the present invention may be compared to some extent with the well-known technique of black and white photography. In black and white the negative obtained may be too soft or too hard depending upon the illumias strongly as.possible.

5 therefore possible in spite of an increased color density of a single layer to obtain neutral images in the printing process by increasing one color component in the negative, provided the printing material used is corrected accordingly.

Example IV Moreover, the process may be advantageously 2 used for the production of sound tracks consisting of dyestuffs. In scanning a color film with white light, only the blue-green layer absorbs nation. According to the gradation characteristics of the negative printing paper of flat gradation is applied for a hard negative and paper of steep gradation is used for a fiatnegative.

in ggeroutput The new process presents a very convenient way of obtaining satisfactory prints 01' the various types of color negatives without necessitating a complicated printing outfit. One single negative color material is used together with a. scale of different brands of positive descent light, one for sun set lig h mountain light. Without applying color filters;

diiierent'colored light-sources and complicated apparatusihe operator willsoon develop the capacity of picking out suitable oi the difierent printing materials,

An exposure in day-light is made on negacarries on a transparent support ared sensitized emulsion to lie-developed into a blue-green image, on topofit, a green sensitized emulsion, to be developed intoa purple image, and furthermore a. third unsensitized emulsion for registering the yellow image. The sensitizatlon'isdone in such a way. that in daylight. a negative or correct, color value 'is'ob tained. This is developed -and the resultant neutrally Example II 5: Apicture or the same object is registered on the same negative material in arc-light, the latter containingisubstantially more blue rays than day-light. -A' negative with an over-balance. of yellow is therefore 'the result. This negative yields bluish images, if copied without precautions. If, however. the print is made on a positive material the dominating color sensitivity of which counter-balances. the fault of the negat and one for balanced posi-.

the actinic rays, as the usual photocells are only [sensitive to red and infrared. An intensification of the blue-green layer results therefore in an increased absorption effect and consequently of the sound film intensifier. In order to obtain a multicolor image of correct color value on a printing material with a surplus of blue-green components, the suitably corrected negative material according to this invention is used for the production oi! the negative.

color print- 'ing material, for instance onepositive material V for arc-light, one for day-light, v one for incanfor each negative the most In the present invention silver halide emulsion layers containing color formers fast to diffusion are advantageously applied, as described in U. S. Patents 2,178,512, 2,179,228, 2,179,239, 2,179,344

We claim:

, 1. A method of producing subtractive. photographic multicolor images of correct color registration which comprises taking a color negative on a photographic multicolor material containother. dyestufl former extent as to compensate the color failure of the tive, an image of correctcolor value is obtained.

With a neutral negative this type of positive material would only give a yellowish image.

ing dyestui! formers in which one of the dyestufi formers predominates and printing said nega- -v tive onto a photographic multilayer printing ma.-

terial containing dyestufl' formers in which anpredominates to such an negative. c

2. A method-oi producing subtractive cinematographic multicolor images of correct color tive on a photographic multicolor material containing dyestuir formers in which one of the dyestuii formers predominates and printing said negative onto a photographic multilayer printing material containing dyestfufl formers in which another dyestufl former predominates .to such an extent as to compensate thecolor Iailureof the negative. 2

3. A method 0 gproducing subtractive cinemat-. ographic multicolor images with sound track of correct color registration which comprises tak- 7 ing a color negative on a photographic multicolor material containing dyestufi formers in which one of the dyestuif formers predominates multilayer printing material containing dyestufl formers in which dominates to such an the color failure of the extent as to compensate negative.

4. Aprocess of making color photographs by registration which comprises taking a color nega- I and printing said negativeonto a photographic o another, dyestufl former prethelnegative-positive process which includes the steps of exposing a negative multi-layer material, having 'dyestufi components in the individual layers balanced for light of given spectral composition, to an object illuminated by light of different spectral composition, developing said negative material in a color-forming developer, to 'produce'dyestufi images the color of which is unbalanced due to color distortion in at least one layer, selecting for the copying material multilayer material containing color formers and having the layer designed to receive that image, the

color of which is distorted, so constituted that on exposure and color development, the color of the image thus produced predominates over that 15 of the images formed in the other layers, and copying the images of said negative material into said copying material with the same source of printing light and while avoiding the use of filters.

5. The process as defined in claim 4 wherein the layer in said copying material which is designed to receive the image, the color of which is distorted, contains a' preponderance of color 0 former over that present in the other layers'of said copying material. I

WILHEIM SCHNEIDER. HEINZ SCHULZE.

GUSTAV WILMANNS.