1. A dry method for forming a colored image by a negative - positive working photographic procedure which comprises: 1. heating a dried recording material, which recording material comprises a support having thereon a color image - forming system comprising a dispersion of discrete oblate spheroids of (a) an organic-halogen compound and (b) a separate color generator which is an organic compound containing a nitrogen atom, in a hydrophilic binder, said organic halogen compound generating halogen ions and/or free radicals containing halogen on irradiation which react with said color generator, and said organic compound containing a nitrogen atom being selected from the group consisting of diphenylamine, n-hydroxydiphenylamine, N-ethyldiphenylamine, o-nitrodiphenylamine, N, N-dimethylaniline, N, N-diethylaniline, N, N, N', N'-tetramethyl-p-phenylenediamine, N-phenyl-alpha-naphthylamine, N-phenyl-beta-naphthylamine, N, N'-dimethyl-alpha-naphthylamine, N, N'-dimethyl-beta-naphthylamine, dibenzylaniline, indole, N-vinylindole, 5-cyanoindole, 3-methylindole, triphenylamine, N, N'-diphenyl-p-phenylenediamine, benzidine, N, N'-diphenylbenzidine, 1, 2-dianilinoethylene, 4,4', 4"-methenyltris (N,N-dimethylaniline), N-vinylcarbazole, p,p'-pentylidenebis(N,N-dimethylanilene), p,p',p"-triaminotriphenyl-carbinol, p,p', p"-triamino-o-methyltriphenylmethane, aniline, carbazole, dibezylamine, N-phenyl-N-methylaniline, bis(p-dimethylaminophenyl)methane, N-phenylindole, o-aminodiphenylamine, p,p'-(dimethylamino)diphenylamine, N-ethylcarbazole, 3-phenyl-indole, p-phenylenediamine, N, N, N', N' -tetramethyl-p-phenylene-diamine, triphenylamine, p, p'-benzylidene-bis (N,N-dimethylaniline), p,p'-benzylidenedianiline, dibenzylethyl amine and dibenzylmethyl amine; 2. thereafter imagewise exposing said recording material to radiation to form a visible color image of the reaction product of said color generator and the product(s) generated from said organic halogen compound; the heating of Step (1) being at a temperature of from about 60.degree. C., to about 150.degree. C., for a time sufficient to increase the density of said visible color image to about twice the density obtained with an otherwise identical recording material which has not been subjected to said heating.