Method of forming a photographic image

A method of forming an image which comprises subjecting an image-wise exposed and developed photographic element comprising a support and at least one photographic layer in which there is image-wise distributed a metallic silver having a catalytic effect to image-wise intensification in the presence of a reducing agent which diffuses into the layer of photographic element from the developer solution or the intensifier solution, or is previously incorporated into the layer, using a solution consisting essentially of at least one of a halogenite, hydrogen peroxide and one or more compounds capable of releasing hydrogen peroxide as an oxidation agent;

• and containing at least one nitro-substituted nitrogen-containing heterocyclic compound represented by the following General formulae (I) and (II);
• ##STR5## in which R.sub.1 represents a hydrogen atom, an alkyl group of 1 to 5 carbon atoms, SO.sub.3 M or COOM wherein M represents hydrogen atom, an alkali metal or an ammonium group, X represents nitrogen atom or CR' wherein R' represents a hydrogen atom or a lower alkyl group of 1 to 5 carbon atoms, and ##STR6## in which R.sub.2 represents hydrogen atom, an alkyl group of 1 to 5 carbon atoms, SO.sub.3 M or COOM wherein M represents hydrogen atom, an alkali metal or ammonium group and Y represents hydrogen atom, an alkyl group of 1 to 5 carbon atoms or CH.sub.2 --S--(CH.sub.2).sub.n --Y' wherein n represents 1 to 3 and Y' represents a hydrogen atom or SO.sub.3 M.