Ciba-geigy Ag

Alfred Oetiker

Max Marthaler

Christoph Chylewski

Herbert Mollet

Carlo Boragine

Production of masked positive color images by the silver dye bleach process, by exposing a photographic material for the silver dye bleach process, silver developing, dye-bleaching, silver-bleaching and fixing, optionally, the step of silver-bleaching is carried out in a combined treatment bath together with dye-bleaching and/or fixing. A photographic material is used which contains (a) in at least one layer, at least one first bleachable image dye, which has at least one undesired color density which is to be compensated, (b) in the layer or layers (a) and/or in a layer adjacent to the said layer or layers (a), an iodide-containing silver halide emulsion allocated to the said dye or to each of the said dyes, (c) in at least one further layer, at least, in each case, a second dye, the main color density of which corresponds to the secondary color density of the first dye or dyes which is to be compensated, (d) in the layer or layers (c) and/or in a layer or layers adjacent to the said layer or layers (c), a silver halide emulsion which is free from iodide or has a low iodide content compared with the emulsion mentioned under (b) and is allocated to the said dye or dyes, and (e) in at least one layer (c) and/or in at least one further layer which is adjacent to the layer or layers (c) and which is separated from one or more layers (a) by at least one interlayer, a fogged silver halide emulsion which is free from iodide or has a low iodide content, is spontaneously developable to maximum density without exposure and contains a development retarder. Developing is carried out in a developer solution which does not contain any silver complexing agents. The resulting color images display outstanding color reproduction.

Process for the production of masked positive color images by the silver

The present invention provides a new process for the production of masked subtractive positive color images by the silver dye bleach process, which comprises the steps of exposure, silver developing, dye-bleaching, silver-bleaching and fixing. The photographic material used contains, in at least two layers, one image-wise bleachable dye per layer, the absorption maximum of the dye corresponding in each case to one of the three primary colors red, green and blue and a silver halide emulsion layer sensitive in a specific spectral region being allocated to each dye, wherein this material (a) in at least one layer contains a dye, the undesired secondary color density of which is to be compensated, and a silver halide emulsion containing silver iodide is allocated to this dye, in the same layer and/or an adjacent layer, (b) in at least one further layer contains at least one further dye, the main color density of which corresponds to a secondary color density, which is to be compensated, of the first dye, and also a silver halide emulsion free from iodide ions, (c) contains a further layer which is adjacent to layer (b) and contains colloidal nuclei which are able, under reducing conditions, to deposit metallic silver from soluble silver complexes, and also contains an insensitive iodide-free silver halide emulsion which is not spectrally sensitized, and optionally a stabilizer, and (d) containing a separating layer, which does not contain any of the dyes of the layer or layers (a), between the layer or layers (a) and the layer (c). The silver developing bath with which the material is treated contains ligands which form water-soluble and diffusible silver complexes with silver.

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Fribourg, Switzerland

Alfred Oetiker