US3252795A - Color correction during the photographic reproduction of a color image - Google Patents

Description

May 24, 1966 M. A. DE RAMAIX ETAL 3,252,795

COLOR CORRECTION DURING THE PHOTOGRAPH-[C REPRODUCTION OF A COLOR IMAGE Filed NOV. 22, 1965 INVENTOR5 BY mam m, @MA f MQW ATTORNEYS tion results.

United States Patent O COLUR CORRECTIGN DURING THE PHOTO- GRAPHIC REPRODUCTION F A COLR IMAGE Maurice Antoine de Ramaix, Hove-Antwerp, and Valre Frans Danckaert, Mortsel-Antwerp, Belgium, assignors to Gevaert Photo-Producten NN., Mortsel-Antwerp, Belgium, a Belgian company Filed Nov. 22, 1963, Ser. No. 325,631 Claims priority, application Germany, Dec. 2, 1957, G 23,457, Patent 1,058,839 6 Claims. (Cl. 96-6) The present invention relates to a method of color correction in the reprod-uction of a color image by photographic and/or graphic means and to a photographic element for use therein; this application is .a continuationin-part of our prior copending application Serial No. 777,224, filed December 1, 1958, now abandoned.

It is generally known that on reproducing a colored object in a photographic way a considerable color devia- In order to reduce this evil, it is advised to use masks. Besides methods where the two or three most important masks are obtained separately, which take up much time, it has been proposed to obtain all the necessary masks simultaneously by the use of a single material. Thus, in `British Patent 562,854, there is proposed a material with two silver halide em-ulsion layers: one sensitive to green and the other sensit-ive to red. The green-sensitive emulsion could contain either a color coupler for yellow, or for green, or a mixture of a color coupler for yellow and of a color coupler for cyan. It also proposed to add the color couplers for yellow and for cyan to distinct emulsion layers. The red-sensitive emulsion would contain either a color coupler for magenta or for blue, or a mixture of a color coupler for magenta and of a color coupler for cyan. It finally proposed to add color couplers for magenta and for cyan, respectively, to distinct layers. The same concept and, in general, the same variations are described in U.S.P. 2,382,690.

If it is desired to practice the above method where,

the green-sensitive emulsion contains a color coupler for green and the red-sensitive emulsion a color coupler for blue, great difculties arise in finding good color couplers for blue and, above all, for green. An alternative is to use, on the one hand, a mixture of color couplers for cyan and for yellow and, on the other hand, a mixture of color couplers for cyan and for magenta. But, since it is practically impossible in color development to have two different color couplers to react in one and the same emulsion at the same rate, one is thus compelled to make a material with four emulsion layers.

It is an object of the present invention to provide a method of color Correction during the reproduction of a color image by photographic and/ or graphic means wherein the use of a color coupler for blue or green as well as the use of a mixture of color couplers is avoided without loss of Vthe corresponding advantages.

It is a further object of the present invention to provide a photographic material which is operative in said method.

Still other objects will appear from the description hereinafter.

These objects are accomplished by the use of a multilayer masking element comprising a transparent support carrying thereon a silver halide emulsion vlayer optically sensitized to both red light and green light and containing a color coupler for cyan, a silver halide emulsion layer optically sensitized to green light and containing a color coupler for yellow, a blue-sensitive silver halide emulsion layer optically sensitized to red light and containing a color coupler for magenta and disposed remote from said support, and a yellow filter layer adjacent said ice blue and red-sensitive layer and separating the same from said two other layers.

The present invention thus mainly relates to a process for reproducing color images wherein for the photographic reproduction step the color image to be reproduced is exposed while in association with a composite mask image containing individual images corresponding, in effect, to the following: a yellow negative of the image to be reproduced obtained by means of exposure through a green filter, a magenta negative of that image obtained by means of consecutive exposures through a blue and a red filter, and a cyan negative image obtained by consecutive exposures through a green filter and a red filter.

Hereinafter follows in the first example a detailed description of a preferred mode of putting the present invention into practice, without, however, limiting its scope thereto, since numerous variants are possible, eg. in the sequence of the two layers located between the support and the yellow filter layer, in the treatment, etc. The material of this example is also shown diagrammatically in an accompanying drawing to facilitate the understanding thereof.

EXAMPLE l A transparent support having its rear side provided with an antihalation layer is successively coated with the following layers:

(1) An emulsion layer sensitive both to green and to red and containing a color coupler for cyan, such as, for instance, 4-sulpho-1-hydroxynaphtho-(2)-octadecylamideg (2) An emulsion layer sensitive to green containing a color coupler for yellow, such as, for instance, m-palmitoylamino-benzoylaceto-3,S-dicarboxyanilide;

(3) A yellow filter layer which contains, for instance, colloidal silver;

(4) An emulsion layer sensitive both to blue and to red and containing a color coupler for magenta, such as, for instance, l-p-sulphophenyl-3-octadecyl-pyrazolone-S.

This material is then used in the following Way: the image to be reproduced is printed on it, either by contact or in optical way. The exposed material is then developed for 5 minutesat 21 C. in a color developer of, for instance, the following composition:

G. N,Ndiethyl-p-phenylenediamine hydrochloride .3 Sodium sulphite (anhydrous) 4 Sodium carbonate (anhydrous) 50 Potassium bromide 1 Hydroxylamine hydrochloride l.2

Water to make cm.3.

rinsed for 21/2 minutes in current of water, treated in a bleach-fixing bath which can be composed, for instance of the following composition:

Monosodium ferrie salt of ethylenediamine tetraacetic acid 37.5 Trisodium ethylenediarnine tetra-acetate 12.5 Sodium thiosulphate (anhydrous) 100 Sodium sulphite (anhydrous) l() Thiourea 5 Water to make 100() cm3.

and finally rinsed for l0 minutes and then dried.

The color-correcting and contrast-reducing mask thus obtained can now be registered with the color image to be reproduced. The registering of the mask and the original can be effected in the usual way, viz the emulsion layer of the mask is brought into contact either with the rear side or with the emulsion side of the color dipositive or color negative. lf special means for registering the mask are provided it is also possible to use the masking material according to the invention in an enlarger or a reprocamera for masking purposes in certain circumstances e.g. on making separations from a multi-color original in reilex (for instance a painting); afterwards, the mask is put in the optical axis of the camera. From the combination thus obtained color separations for graphic purposes or prints upon a three color material (negative or reversal development) can be made in contact or in optical way.

EXAMPLE 2 In order to demonstrate the functional superiority of the present invention over t-he prior art method, a comparison was made between a mask element prepared as in Example l above and a mask element constructed as in FIG. 4 0f U.S. Patent 2,382,690 and consisting in order on a support of a red-sensitive emulsion layer containing a cyan coupler, a second red-sensitive emulsion layer containing a magenta coupler, and an exterior green-sensitive layer containing a yellow color coupler. The couplers for cyan, magenta, and yellow, respectively, were the same in both elements and the formulation of the constituents as well as the processing procedures employed were carried out in as close to an identical manner as reasonably possible to give a faithful comparison Each of the experimental masks so prepared was exposed with white light through a glass strip containing three color wedges in the three complementary colors magenta, cyan and yellow, the dyestuts of which are mixed physically in such a way as to give an absorption corresponding to that of the originals from which the separation negatives are made. After processing, each mask element is registered with the glass strip and the registered color wedges are then measured behind a blue, green, and a red filter for absolute gamma-values.

For more direct comparison, the absolute gamma-values are adjusted to a common basis by converting the absolute values for the principal absorption of each dyestuff, e.g. green light absorption for the magenta dyestuf, blue light absorption for the yellow dyestuff, etc. to 100 and multiplying the absolute gamma-values for the sideabsorptions by the same conversion factor. The resultant relative gamma-values for the two experimental masks, the prior art mask being identified as II and that of this invention as III, are set forth in the following table together with the corresponding values desired in a theoretically ideal mask, identied as I. A theoretically ideal mask is one giving good color reproduction, taking into consideration the average side-absorptions of the dyestus of the original to be reproduced and the average sideabsorptions of commercially available printing inks.

Table MASK LAYER RELATIVE GAMMA-VALUES FOR:

Evaluating these results, the following conclusions can be drawn:

(l) As to blue side-absorption by the magenta dyestuff, mask Il is within and mask III is just out of the ideal limits;

(2) As to blue side-absorption by the cyan dyestullc,v

mask II shows considerable overcorrection, and mask III is Within the ideal limits;

(3) As to green side-absorption by the yellow dyestu?, mask II shows some undercorrection, whereas mask III is within the ideal limits;

(4) As to green side-absorption by the cyan dyestuff, mask II shows considerable overcorrection, whereas mask III is within the ideal limits;

(5) As to red side-absorption by the yellow dyestuif, mask II falls just outside with a slight undercorrection; and mask III falls within the ideal limits;

(6) As to the red side-absorption by the magenta dyestuff, mask II shows quite considerable undercorrection and mask III a negligible undercorrection.

From the above, it will be seen that the two experimental masks give comparable correction except for blue and green light side-absorptions by the cyan dyestuff for which mask II provides considerable overcorrection, and for red light side-absorption by the magenta dyestuff for which mask II provides considerable undercorrection.

It is clear that due to these considerable correction deviations in three areas of mask II, mask III exhibits subsantial superiority over mask II.

What we claim is:

1. A multi-layer color photographic masking element for applying color correction during color reproduction comprising a transparent support carrying thereon:

(1) a silver halide emulsion layer optically sensitized to both red light and green light and containing a color coupler for cyan,

(2) a silver halide emulsion layer optically sensitized to green light and containing a color coupler for yellow,

(3) a blue-sensitive silver halide emulsion layer optically sensitized to red light and containing a color coupler for magenta and disposed remote from said support, and

(4) a yellow lter layer adjacent said blue-red sensitive layer (3) and separating the same from said other layers (1) and (2).

2. A color photographic masking element as in claim 1, wherein the color coupler for cyan is 4-sulpho-1-hydroxynaphtho-(2)-octadecylamide.

3. A color photographic masking element as in claim 1, wherein the color coupler for magenta is l-p-sulphophenyl- 3-octadecyl-pyrazolone-S.

4. A color photographic masking element as in claim 1, wherein the color coupler for yellow is m-palmitoylaminobenzoylaceto-3,5-discarboxyanilide.

5. A color photographic masking element comprising on a transparent support the following layers in the stated order:

(l) a silver halide emulsion layer optically sensitized to green and to red and containing a coupler for cyan;

(2) a silver halide emulsion layer optically sensitized to green and containing a coupler for yellow;

(3) a yellow ilter layer containing colloidal silver; and

(4) a blue-sensitive silver halide emulsion layer optically sensitive to red and containing a color coupler for magenta.

6. In a method of color reproduction of a colored original on light-sensitive reproduction material, the improvement of etTecting color correction in the reproduction coloration by the steps of exposing to said original the masking element of claim 1 and, after color processing of the masking element thus exposed, exposing the lightsensitive reproduction material to said original and the developed masking element while the latter are in optical registration.

References Cited by the Examiner FOREIGN PATENTS 811,311 4/1959 GreatBritain.

NORMAN G. TORCHIN, Primary Examiner.

J. T.,BROWN, Assistant Examiner.

Claims (2)

1. A MULTI-LAYER COLOR PHOTOGRAPHIC MASKING ELEMENT FOR APPLYING COLOR CORRECTION DURING COLOR REPRODUCTION COMPRISING A TRANSPARENT SUPPORT CARRYING THEREON: (1) A SILVER HALIDE EMULSION LAYER OPTICALLY SENSITIZED TO BOTH RED LIGHT AND GREEN LIGHT AND CONTAINING A COLOR COUPLER FOR CYAN, (2) A SILVER HALIDE EMULSION LAYER OPTICALLY SENSITIZED TO GREEN LIGHT AND CONTAINING A COLOR COUPLER FOR YELLOW, (3) A BLUE-SENSITIVE SILVER HALIDE EMULSION LAYER OPTICALLY SENSITIZED TO RED LIGHT AND CONTAINING A COLOR COUPLER FOR MAGENTA AND DISPOSED REMOTE FROM SAID SUPPORT, AND (4) A YELLOW FILTER LAYER ADJACENT SAID BLUE-RED SENSITIVE LAYER (3) AND SEPARATING THE SAME FROM SAID OTHER LAYERS (1) AND (2).

6. IN A METHOD OF COLOR REPRODUCTION OF A COLORED ORIGINAL ON LIGHT-SENSITIVE REPRODUCTION MATERIAL, THE IMPROVEMENT OF EFFECTING COLOR CORRECTION IN THE REPRODUCTION COLORATION BY THE STEPS OF EXPOSING TO SAID ORIGINAL THE MASKING ELEMENT OF CLAIM 1 AND, AFTER COLOR PROCESSING OF THE MASKING ELEMENT THUS EXPOSED, EXPOSING THE LIGHTSENSITIVE REPRODUCTION MATERIAL TO SAID ORIGINAL AND THE DEVELOPED MASKING ELEMENT WHILE THE LATTER ARE IN OPTICAL REGISTRATION.

Images