Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C7/00—Multicolour photographic processes or agents therefor; Regeneration of such processing agents; Photosensitive materials for multicolour processes
  • G03C7/18—Processes for the correction of the colour image in subtractive colour photography

Definitions

• This invention relates to colour photography and particularly to methods and materials for obtaining corrected colour images.
• the blue-sensitive emulsion since it is in fact the only emu sion which is allowed to record the blue light received from the subject photographed. It will further be understood that in speaking of the blue-sensitive emulsion as an outer layer, it is meant that the blue-sensitive layer is not located between the other two layers: it mav be closest to the support or the most remote from the support, but should in either case be the layer on which the light of the exposure is first incident.
• colourformers are com ounds which combine with the oxidation products formed during development by means of an aromatic primary amino developing agent, to form awomethine or quinoneimine dyestufi images in situ with the developed silver images, and colour development is the term applied to the production of such dyestuff images.
• the colour-formers may be included in the emulsion layers or may be in layers adjacent thereto, or may be contained in co loid media, e. g. grains of hydrophilic colloid, dispersed through the emulsion layers.
• co loid media e. g. grains of hydrophilic colloid
• the original material may be processed to a negative and this may be copied on to another multilayer photographic material, which in turn may be developed to a positive: in this negative-positive technique the colour-formers present in the layers of the materials need not be such as will yield dyes complementary in colour to the sensitivities of the emulsions (as is broadly essential in the reversal technique), but providing the dyes are respectively subtractive to the primaries they may be generated in any of the emulsion layers, the correction being efiected by an appropriate choice of colour sensitivity and colour-former assembly in making the positive print.
• Such processes are referred to as false-colour processes and in further explanation of the technique, attention is drawn to British Patents Nos. 475,784 and 475,786.
• each dye image which absorbs light in wavelengths which it should ideally transmit is provided with a complementary image (1. e. a positive where the original is a negative and vice versa) which absorbs light of said wavelengths to an extent such that the absorption of light of such wavelengths over both images is substantially constant. It will be appreciated that by this means the effect of the unwanted absorptions is masked out in the sense that, over those wavelengths, the layer containing the dye image will cast no image on a printing material.
• British Patent No. 591,124 there is described a method of forming a coloured colloid layer which comprises forming a layer of a water-permeable colloid containing a surface-active compound and thereafter applying to such layer an aqueous solution of a dyestuff which has an opposite electrostatic charge to that carried by said surface-active compound.
• the surface-active compound and the dye appear to form a complex which, thoughstable under ordinary conditions, canbe broken down .by suitable treatment.
• British Patent No. 591,124 there is described a method of forming a coloured colloid layer which comprises forming a layer of a water-permeable colloid containing a surface-active compound and thereafter applying to such layer an aqueous solution of a dyestuff which has an opposite electrostatic charge to that carried by said surface-active compound.
• the surface-active compound and the dye appear to form a complex which, thoughstable under ordinary conditions, canbe broken down .by suitable treatment.
• a substantive colourformer which has an acid substituent grouping in the position at which the colour-former couples on colour-development, which grouping is eliminated on such colour-coupling, which colourformer is therefore capable of combining with a basic dye to form a dye complex
• a dye image is formed by colour development in said layer and the layer is thereafter treated with a basic dyestuff to form a complex with the residual colourformer, the colour of the complex being different from that of the said colour-formed dye image.
• the colour of the complex is such that it absorbs only light of those wave-lengths for which the colourformed dye image shows an unwanted absorption, so that the absorption of those wavelengths is substantially constant throughout the layer.
• an image in dye complex complementary i. e. positive where the colourformed image is negative and. vice versa
• Colourformed cyan dye images generally absorb too highly in the blue and, to a lesser extent, in the green regions of the spectrum and accordingly the optimum colour for the masking image is an orange.
• Colour-formed magenta dye images generally absorb too highly in the blue region of the spectrum and a yellow masking image is therefore suitable.
• Colour-formed yellow images generally require little correction and for that reason it .is preferred, in the present invention, that the yellow colour-former should not have surface-active properties. It will be appreciated therefore that a fair degree of correction can be effected by the provision of yellow images complementary to the cyan and magenta images only, and it is therefore possible to efiect a substantial colour correction by the use of a single masking dye.
• Suitable basic dyes for-use with-these are:
• Rhodamine (Colour Index No. 655) Rhodamine B (Colour Index No. 749) Rosaniline Hydrochloride (Colour Index No. 677) Malachite Green (Colour Index No. 657)
• Rhodamine is a registered trademark.
• the fundamental procedure of the present invention may be illustrated by considering .a single layer of photographic emulsion coated on a support, for example a layer of a silver iodobromide emulsion having a coating weight of 20 mgm. of silver per squaredecimetre and 5 mgm. per square decimetre of the colour-former 1-hydroxy-2-N- stearylacetamino napthalenei-sulphonic acid.
• This material was exposed behind a step wedge and colour developed, thus producing a negative cyan dye image.
• the silver and silver halide in the layer were then removed by treatment with farmers reducer. The material was then bathed in a 0.1% aqueous solution of Auramine O and the film was washed in running water for 20 minutes.
• Example 1 A photographic element is prepared consisting of the following layers in super position in the order stated:
• Filter layer consisting of a dispersion of yellow colloidal silver in gelatin.
• Gelatino silver iodobromide emulsion having a natural sensitivity in the blue region of the spectrum and substantially insensitive to the green and red regions of the spectrum and containing the yellow colour-former 4.4.-'-dibenzoylacetbenzidide.
• cc 160 Sodium sulphate (Na2SO3.7 H20) (20% solution)
• cc Potassium bromide g 0.1 Water to make cc 400 The element is then bathed in farmers reducer which removes silver and silver salts leaving a negative colour image of the original object.
• the element is then bathed in an aqueous solution containing 0.1% Auramine O and 0.05% Rhodamine B.
• the film is then washed in water for minutes when a yellowish-red image is obtained in the greenand red-sensitive layers only where no magenta or cyan dye image was produced during the colour development.
• This yellowish-red image forms a satisfactory masking image for the imperfections of the magenta and cyan colour-formed images so that when the element is used as a medium from which positive colour records are to be made a substantial degree of colour correction is achieved.
• Example 2 A photographic element was prepared as in Example 1 except that the colour-formers in layers (c) and (e) were respectively l-m-stearoylamino phenyl-3-methylsulpho-S-pyrazolone and stearoylacet-o-chloranilide.
• the element was processed to produce a negative colour record as in Example 1 and was then bathed in a 0.1% solution of Auramine O. After washing in water a yellow masking image is formed complementary to the cyan and magenta colour-formed images.
• the original multilayer photographic element may be processed to a positive transparency so that it may be viewed as such and then at any subsequent time may be treated to form mashing images in the layers in order to correct the undesired absorptions of the colour-formed images, and thus provide a satisfactory medium for the production of duplicate colour prints.
• the complex between the colour-former and the dye may be formed initially and introduced as such into the photographic layers, or may be formed in situ in the photographic layers at any stage in the handling of the material. If this procedure is adopted, however, care should be taken to avoid the use of any strongly acid or strongly alkaline processing bath as this may affect the complex undesirably.
• the present invention presents important advantages over processes which have previously been described for the production of integral masking images.
• no special colour-formers are required since colour-formers which possess the desired properties are already well-known.
• the method is applicable both to the treatment of reversal material and to material which is processed first to a negative and from which positive copies are made.
• the masking dye images can be removed whenever desired and replaced whenever desired, and in being replaced may be changed in hue.
• the density of the masking image can be quite simply controlled by regulating the concentration of dye in the dye bath used and the time of bathing, and also by washing or the controlled removal of any excess density.
• a process for the production of a colourcorrected photographic record which comprises subjecting a photographic material which contains in at least one layer; a substantive colourformer which has in the position at which the said colour-former couples on colour development an acid grouping selected from carboxylic and sulphonic acid groups and also contains a record dye image obtained by such coupling development, the said dye image undesirably absorbing to some extent light of wavelengths which it is desired that it should transmit, to treatment with a basic dye, thereby forming with the residual colour-former in the said layer an image of opposite sign to the said record dye image, the said image of opposite sign being in a complex of such residual colour-former and said basic dye, the hue and intensity of such image of opposite sign being such that it absorbs light of at least some of the wavelengths which the record dye image undesirably absorbs, so that the absorption of such wavelengths is substantially uniform over the whole layer, and transmits more freely than the record dye image in the remaining wavelengths.
• a process for the production of a colourcorrected photographic record which comprises exposing to a coloured object a multi-layer photographic material comprising a support and superimposed on one side of the support three silver halide emulsion layers one of which is sensitised for the red region of the spectrum, one is sensitised for the green region of the spectrum, and one is sensitive only to the blue region of the spectrum, the said material containing substantive colour-formers respectively in coactive relationship to said emulsion layers and adapted severally to yield, on colour-development, dye images which are subtractive with respect to the primary colours, at least one of said colourformers (A) having in the position at which it couples on colour-development an acid grouping selected from carboxylic and sulphonic acid groups and yielding on colour-development a record dye image which undesirably absorbs to some extent light of wavelengths which it is desired that it should transmit, subjecting the said photographic material to colour-development to form dye record images in the three subtractive colours, and treating the resulting material with abasic dyes
• a process for the production of a colourcorrected photographic record which comprises exposing to a coloured object a multi-layer photographic material comprising a support and superimposed on one side of the support three silver halide emulsion layers one of which is sensitised for the red region of the spectrum, one
• the said material containing substantive colour-formers respectively in coactive relationship to said emulsion layers and adapted severally to yield, on colour-development, dye images which are yellow, magenta and cyan in colour, the yellow colour-former being free from acid groups and one of the magenta and cyan colour-formers having in the position at which it couples on colour-development an acid grouping selected from carboxylic and sulphonic acid groups and yielding on colour-development a record dye image which undesirably absorbs to 8 in each of the layers containing such colourformers.
• both the magenta and cyan colour-formers are acid colour-formers and images of sign opposite to the record images are formed in a complex of the residue of such colour-formers and a yellow to red basic dye in each of the layers containing such colour-formers.
• a process for the production, of a colourcorrected photographic record which comprises exposing to a coloured object a multi-layer photographic material comprising a support and superimposed on one side of the support three silver halide emulsion layers one of which is sensitised for the red region of the spectrum, one is sensitised for the green region of the spectrum, and one is sensitive only to the blue region of the spectrum, the said material containing substantive colour-formers respectively in coactive relationship to said emulsion layers and adapted severally to yield, on colour-development, dye images which are yellow, magenta and cyan in colour, the yellow colour-former being free from acid groups and one of the magenta and cyan colour-formers having in the position at which it couples on colour-development an acid grouping selected from carboxylic and sulphonic acid groups and yielding on colour-development a record dye image which absorbs undesirably to some extent light of wavelengths which it is desired that it should transmit, subjecting the said photographic material to colour-development to form dye record images in yellow,
• a process for the production of a colourcorrected photographic record which comprises exposing to a coloured object a multilayer photographic material comprising a support and superimposed on one side of the support three silver halide emulsion layers one of which is sensitised for the red region of the spectrum, one is sensitised for the green region of the spectrum, and one is sensitive only to the blue region of the spectrum, the said material containing substantive colour-formers respectively in coactive relationship to said emulsion layers and adapted severally to yield, on colour-development, dye images which are yellow, magenta and cyan in colour, the yellow colour-former being free from acid groups and one of the magenta and cyan colour-formers having in the position at which it couples on colour-development an acid grouping selected from carboxylic and sulphonic acid groups and yielding on colour-development a 9 record dye image which absorbs undesirably to some extent light of wavelengths which it is desired that it should transmit, subjecting the said photographic material to colour-development to form dye record images in yellow, mag

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  • NL NL656507891A patent/NL148537B/nl unknown
  • NL NL75496D patent/NL75496C/xx active
• 1948
  • 1948-09-07 GB GB23552/48A patent/GB643706A/en not_active Expired
• 1949
  • 1949-08-31 US US113476A patent/US2595768A/en not_active Expired - Lifetime

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