Acutance agents for use in thermally developable photosensitive compositions

A compound which has a maximum absorption of visible light between 440 and 460 nm and which provides a flare factor of less than 0.9 to photosensitive emulsion coatings said compound having the general formula:

• ##STR32## wherein:
• R.sup.1 represents hydrogen, an alkyl group of 1 to 18 carbon atoms or an aryl group of 6 to 10 carbon atoms, the alkyl or aryl group optionally substituted by halogen, by an alkoxy group of 1 to 6 carbon atoms or by an aryl group of 6 to 10 carbon atoms;
• R.sup.2 and R.sup.3 independently represent hydrogen, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or halogen;
• R.sup.4 and R.sup.6 independently represents hydrogen, nitro, cyano, a carbalkoxy group having 1 to 6 carbon atoms, or halogen, and at least one of R.sup.4 and R.sup.6 is a nitro, cyano, carbalkoxy group having 1 to 6 carbon atoms, or halogen;
• R.sup.5 is hydrogen;
• or
• R.sup.5 and R.sup.6 together constitute a benzo group.