Method for forming a direct positive image

Abstract

A method of forming a direct positive image comprising: (a) imagewise exposing a direct positive silver halide photographic material composed of a support having thereon at least one light-sensitive silver halide emulsion layer containing non-prefogged internal latent image silver halide grains, at least one hydrophilic colloidal layer of the material containing a nucleating agent, and at least one sensitizing dye represented by formulae (I), (Ia), (Ia'), or (Ib): ##STR1## wherein Z and Z.sub.1 each represents a non-metallic atomic group necessary for forming a 5-membered or 6-membered nitrogen-containing heterocyclic ring; R and R.sub.1 each represents a substituted or unsubstituted alkyl group or an aryl group; Q and Q.sub.1 represent a non-metallic atomic group necessary for forming together a 4-thiazolidinone group, a 5-thiazolidinone group or a 4-imidazolidinone group; L, L.sub.1 and L.sub.2 each represents a methine group or a substituted methine group; n.sub.1 and n.sub.2 each is 0 or 1; X represents an anion; and m is 0 or 1; ##STR2## wherein R.sub.21 and R.sub.22 each represents a substituted or unsubstituted alkyl group; R.sub.20 represents hydrogen, a methyl group, a methoxy group or an ethoxy group; R.sub.23 and R.sub.24 each represents hydrogen, a lower alkyl group, a phenyl group or a benzyl group; R.sub.25 represents hydrogen, a lower alkyl group, a lower alkoxy group, a phenyl group, a benzyl group or ##STR3## wherein W.sub.1 and W.sub.2 each represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, and W.sub.1 and W.sub.2 may be linked to form a 5-membered or 6-membered nitrogen-containing heterocyclic ring; D.sub.20 represents a substituted or unsubstituted group containing at least one ethylene bond; D.sub.21 and D.sub.22 each represents hydrogen or a group containing an ethylene bond, when D.sub.21 and D.sub.22 are linked to form a ring; Z.sub.20 and Z.sub.21 each represents a non-metallic atomic group necessary for forming a 5- membered or 6-membered nitrogen-containing heterocyclic ring; X' represents an acid anion; and n' is 1 or 2; ##STR4## wherein R.sub.36 and R.sub.37 each has the same definition as R.sub.21 ; R.sub.38 has the same definition as R.sub.23 ; V represents hydrogen, a lower alkyl group, an alkoxy group, a halogen atom, or a substituted alkyl group; Z.sub.32 has the same definition as R.sub.20 ; X.sub.1 has the same definition as X; and m.sub.1, n.sub.1 and p is each 1 or 2 and (b) developing said exposed material in the presence of a nucleation accelerator to form a positive image.