Metal complexes, particularly copper and nickel complexes of azo dyes corresponding to general formula (I) are suitable as color dyes for the production of color images by the dye diffusion transfer process. The dyes are (in non-metallized form), in the form of so-called "dye-releasers", bound to a redox-active carrier radical provided with a ballast group, which dye-releasers are associated to a light-sensitive silver halide emulsion layer. During development, the metallizable dyes are image-wise released and are converted, after diffusion into a light-receiving layer, into the corresponding metal complexes ##STR1## wherein E represents an electron acceptor radical; andK represents the radical of an azo coupler component, derived from an open-chain or closed ring ketomethylene compound, a cyclic enamine compound or a phenolic compound.