Abstract: Novel dyes are described for sepctrally sensitizing direct-positive silver halide emulsions comprising fogged silver halide grains. The dyes correspond to the formula: ##SPC1##Wherein:R.sub.1 is hydrogen, an alkyl group, an aryl group, or an acyl group,Each of R.sub.2 and R.sub.3 represents hydrogen, carboxyl, sulpho, nitro, cyano, halogen, an alkyl group or an aryl group,Each of L.sub.1 and L.sub.2 represents a methine group, m is 1 or 2, Y is O, S, Se or ##EQU1## R.sub.4 represents an aliphatic group or an aromatic group, X.sup.-represents an anion but does not exist when the molecule itself contains an anionic group, and Z represents the atoms necessary to close a fused-on benzoor naphtho-ring carrying one or more substituents at least one of which is a COR.sub.5 or SO.sub.2 R.sub.6 group wherein R.sub.5 is alkyl, aryl, hydroxyl, O-alkyl, NH.sub.2, NH-alkyl, NH-aryl, ##EQU2## AND R.sub.6 is alkyl, aryl, NH.sub.