Agfa-gevaert Ag

Agfa Gevaert Nv

Otto Lapp

Joachim W Lohmann

Erwin Ranz

Sieghart Klotzer

Harald Von Rintelen

Lothar Endres

Erik Moisar

Peter Bergthaller

Wolfgang Schmidt

Klaus Wagner

Immo Boie

Arno Schmuck

Wilhelm Saleck

Willy Joseph Vanassche

Franz Moll

Herman Alberik Pattyn

Bruno Mucke

J Org Siegel

Gerhard Kuhn

The production of a silver halide emulsion in an aqueous protective colloid solution by the reaction of, on the one hand, silver nitrate, and, on the other, at least one water-soluble halide, may be performed particularly simply and with great apportioning accuracy, if, during at least part of the precipitation, at least the predominant part of one reactant is added in the form of a solid salt to the aqueous protective colloid solution.

Production of silver halide emulsions

A silver halide having at least two halides of differing atomic numbers may successfully be produced with a more uniform halide distribution within certain zones or throughout the entire volume of the individual grain and from grain to grain, if a portion or the entire quantity of the halide of the higher atomic number is dissolved in an aqueous silver salt solution and the resulting solution is introduced at any stage into the emulsion preparation process.

Process for the production of silver halide emulsions

A color photographic print material with the usual three different sensitized silver halide emulsion layers and at least one silver halide emulsion layer containing no color coupler (control layer) with a spectral sensitization range outside the sensitization range of the image-producing layers, wherein the control layer contains a substance A, which, on negative development of the silver halide emulsion used in the control layer (control emulsion), releases a compound B which alters the gradation of the image-producing layers, is usable as a print material with variable gradation.

Colour print material with variable gradation

A color photographic silver halide material comprising at least one negatively developing, green-sensitive silver halide emulsion layer containing at least one magenta coupler can be adjusted to any desired sensitivity of that layer without any changes in other sensitometric properties by addition of at least one compound corresponding to general formula (I) ##STR1## wherein is hydrogen or halogen,

Color photographic silver halide material

Silver halide emulsions are prepared by precipitating a silver halide emulsion I on a more sparingly soluble silver halide emulsion II in the presence of a silver halide solvent wherein the emulsion I has been prepared in the presence of a compound inhibiting grain growth.

Process for the preparation of silver halide emulsions, photographic

New thioethers of the formula ##STR1## in which Ac represents an acyl radical have been found. They are useful for producing silver halide emulsions for photographic materials.

Production of photographic silver halide emulsion

A high sensitivity color photographic recording medium has at least two red sensitive component silver halide emulsion layer and at least three green sensitive component silver halide emulsion layers, the sensitivity of layers of the same spectral sensitivity increasing in the direction from the layer support upwards and the more sensitive red-sensitive silver halide emulsion being located between two of the green-sensitive silver halide emulsion layers.

Color photographic recording material

In a color photographic material comprising a plurality of light-sensitive and non light-sensitive layers including at least two red sensitive coupler-containing silver halide emulsion layers of different speed, at least two green sensitive coupler-containing silver halide emulsion layers of different speed and a blue sensitive coupler-containing silver halide emulsion layer as well as a yellow filter layer located closer to the support than the blue sensitive silver halide emulsion layer but further removed from the support than any of the red sensitive or green sensitive layers, the sensitivity of the cyan partial image is significantly improved if the more sensitive red sensitive together with the more sensitive green sensitive silver halide emulsion layer forms a comparatively more sensitive emulsion layer unit which is located further removed from the support than a corresponding comparatively less sensitive emulsion layer unit formed by the less sensitive green sensitive and the less sensitive red sensitive silver halide emulsion layer, and the uppermost silver halide emulsion layer within the comparatively less sensitive emulsion layer unit is sensitive to the same spectral region as the lowermost silver halide emulsion layer within the comparatively more sensitive emulsion layer unit.

In a color photographic recording material comprising two red sensitive silverhalide emulsion layers of differing speed and two green sensitive silver halide emulsion layers of differing speed and a blue sensitive silver halide emulsion layer wherein each of the silver halide emulsion layers has associated with it a non-diffusing color coupler, and in which the more sensitive red sensitive silverhalide emulsion layer and the more sensitive green sensitive silver halide emulsion layer together form a comparatively more sensitive emulsion layer unit, the sensitivity for red and green light as well as for blue light is increased by placing the yellow filter layer immediately below the comparative more sensitive emulsion layer unit.

Direct positive silver halide emulsions are provided which contain fogged homodisperse silver halide grains having a silver iodide content of more than 10 mole % and at most 20 mole % relative to the total amount of silver halide. These emulsions have higher sensitivity than corresponding fogged emulsions with less silver iodide content.

Direct positive emulsions containing fogged, monodispersed silver halide

Equidensity images can be produced by imagewise exposure and photographic processing of a photographic material containing at least two silver salt emulsions which may be arranged in one layer as a mixture or in two layers, wherein one silver salt emulsion is a fogged direct positive emulsion and the other is a negative emulsion.

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Leverkusen, Germany

Otto Lapp