Photographic speed increasing and latent image stabilizing compounds, silver halide emulsions, and photographic elements

In a color photographic element comprising a support bearing at least one blue-sensitive silver halide emulsion layer having associated therewith a yellow dye-forming coupler, at least one green-sensitive silver halide emulsion layer having associated therewith a magenta dye-forming coupler, and at least one red-sensitive silver halide emulsion layer having associated therewith a cyan dye-forming coupler, the improvement wherein at least one of the silver halide emulsion layers contains a latent image stabilizing amount of a compound represented by the formula:

• ##STR20## wherein:
• X and Y complete a heterocyclic nucleus chosen from the class consisting of benzoxazole, benzothiazole, benzoselenazole, and benzimidazole;
• Z is ##STR21## R is hydrogen or lower alkyl.

A color photographic element in which R is hydrogen or methyl.

A color photographic element in which said compound is present in a concentration of from 0.02 to 0.3 millimole per silver mole.

A process comprising incorporating in a photographic silver halide emulsion in a photographically effective amount a compound represented by the formula ##STR22## wherein:

• X is oxygen, sulfur, selenium, or nitrogen;
• Y is the atoms necessary to complete a fused aromatic nucleus;
• Z is ##STR23## R is hydrogen or lower alkyl of from 1 to 5 carbon atoms.