Method of stabilizing organic substrates against the action of light

A method of improving the light fastness of a photographically useful organic substrate material selected from the group consisting of an anthraquinone dye, a quinoneimine dye, a methine dye, an azo dye, an azomethane dye, a polymethine dye, an indoamine dye, an indophenol dye, a carbonium dye, an indigoid dye, a formazane dye and a fluorescent whitening agent having an absorption peak between about 300 and about 800 nm which comprises making co-exist with said substrate material at least one compound represented by the following general formula (I) ##STR25## where M represents a metal atom selected from the group consisting of Cu, Co, Ni, Pd and Pt;

• X.sub.1, X.sub.2, X.sub.3 and X.sub.4 each represents an oxygen or sulfur atom;
• R.sub.1 and R.sub.2 each represents an alkyl group, an aryl group, a cycloalkyl group, an oxocycloalkyl group or an heterocyclic group which may be substituted or unsubstituted and which may be attached to the carbon atom on the chelate ring directly or through a divalent connecting group;
• R.sub.3 represents a hydrogen atom, an alkyl group, an aryl group, a cycloalkyl group, an oxo-cycloalkyl group or a heterocyclic group which may be substituted or unsubstituted and which may be attached to the carbon atom on the chelate ring directly or through a divalent connecting group;
• R.sub.1, R.sub.2 and R.sub.3 may be the same or different and R.sub.1 and R.sub.3, or R.sub.2 and R.sub.3 may combine to form the non-metallic atoms necessary to complete a 5-, 6- or 7-membered nucleus, said compound of the formula (I) being present in a stabilizing amount which does not adversely affect color hue as well as color purity of the photographically useful organic substrate material.