Agfa Gevaert Nv

Agfa-gevaert Ag

Herman Adelbert Philippaerts

Robert J Pollet

Willy Joseph Vanassche

Francois Leon Schelfaut

Anita Von Konig

Francis J Sels

Theofiel H Ghys

Rene Omer Duville

Hubert Vandenabeele

Wilhelm Saleck

Franz Moll

Herman Alberik Pattyn

Jozef Frans Willems

Antoon Leon Vandenberghe

Luc A De Brabandere

Walter Gauss

Jules Robert Berendsen

Robrecht Julius Thiers

Wolfgang Muller-Bardorff

Herbert Gernet

Compounds of the formula ##STR1## are useful as stabilizers in photographic materials.

Photographic emulsion with stabilizer process for its preparation,

Fine-grain silver halide emulsions of the Lippmann-type are described which comprise derivatives of heterocyclic mercaptans corresponding to the formulae: ##STR1## wherein: each of Z.sub.1 and Z.sub.2 represents the atoms necessary to complete a 5- or 6-membered heterocyclic ring system,

Photographic Lippmann emulsions

A method is described of making reversal images in Lippmann-emulsions wherein the emulsion is image-wise exposed and subjected to a first stage development so that a negative silver image of the original is formed but some silver halide is left in the exposed areas, and then to a second stage development under fogging conditions to develop said residual silver halide in the exposed areas, whereafter the silver developed in said first and second development stages is bleached and the active silver halide then still remaining in the emulsion is converted to form a positive image.

Reversal processing of exposed Lippman-emulsions

A method for producing photographic images by development of an exposed silver halide element at elevated temperature is provided wherein the development occurs in the presence of a non-quaternary, non-heterocyclic nitrobenzene compound of the formula: ##STR1## WHEREIN: (R).sub.n stands for one or more substituents selected from hydrogen, halogen, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, alkoxy, substituted alkoxy, alkylmercapto, substituted alkylmercapto, amino, substituted amino, aryl, substituted aryl, hydroxy, nitro, cyano, sulpho or carboxy in acid or salt form, alkoxycarbonyl and an acyl group derived from a carboxylic or sulphonic acid. The nitrobenzene compounds have a favorable effect on the sensitometric properties of the silver halide emulsion that are developed at elevated temperature. They reduce the supplemental fog produced by development at elevated temperature.

High temperature processing of photographic silver halide material

A photographic material is described for making positive images by reversal processing, the material comprising a support and a silver halide Lippmann-emulsion layer the average silver halide grain-size of which is less than 100 nm wherein the grains have been chemically sensitized to fog so that a test portion of the emulsion when coated on a support at a coverage of silver halide corresponding to from about 3 g to about 7 g of silver nitrate per sq.m. gives a density between about 0.20 and about 0.70 upon development without exposure for 6 min at 20.degree. C in a developer of the composition:

Lippmann-emulsions and reversal processing thereof

Reduction and gold fogged Lippmann emulsions are described wherein the emulsion is fogged with from 0.07 to 0.5 milliequivalents of reduction fogging agent and from 0.01 to 0.1 millimole of gold fogging agent per mole of silver halide and the emulsion comprises more than 2 g and at most 10 g of electron acceptor(s) per mole of silver halide.

Direct-positive silver halide emulsions

A method of developing an exposed lith-type silver halide emulsion is described wherein development takes place in the presence of a sulphonium compound corresponding to the formula: ##STR1## wherein: EACH OF X.sub.1 and X.sub.2 represents an alkyl group at least one of which carries a hydroxy, carboxy, sulpho or cyano group,

Development of exposed lith-emulsions

A process is described of improving the development characteristics of photographic silver halide elements by the use of compounds corresponding to the formula:

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Edegem, Belgium

Herman Adelbert Philippaerts