Verfahren zur Verarbeitung eines belichteten photographischen Materials mit Gelbfilterschicht

A preparation of a Schiff's base of formula:- in which B is a benzene or naphthalene radical, A an aromatic radical containing a sulpho or carboxy group, and M hydrogen or a salt-forming radical, and the hydroxyl group is ortho to the azomethine linkage, involves condensation of potassium-6-hydroxy -5- formyl-naphthalene -2- sulphonate with 1-octadecyl -2- (41aminophenyl), benzimidazole-5-sulphonic acid; and numerous aromatic hydroxy compounds for formation of radical B, sulfo and carboxy compounds for radical A, and alkali metals and amino compounds for radical M are listed. The bases are yellow dyes irreversibly decolourisable by aliphatic or aromatic-aliphatic primary amines, a selection of which is also listed.