This invention relates to a mixture of imageable polyacetylenic compounds which have similar photosensitivities and which are visually imageable in complementary colors combinable to provide a black image, which mixture contains at least one polyacetylenic metal salt which produces a color, preferably a metal salt of a diacetylene C.sub.6 to C.sub.48 mono- or dicarboxylic acid, which is complementary to a color produced by another polyacetylenic metal salt or non-metallic polyacetylenic compound contained in the mixture or in an another integral color forming layer. The invention also pertains to the use of said mixture and the manner of its preparation.