Silver halide photographic materials

A process for forming a high contrast image composed of dots and lines which comprises image-wise exposing a silver halide photographic material comprising a support having coated thereon a silver halide emulsion layer containing at least one sensitizing dye represented by the following formula (I) and at least one sensitizing dye represented by the following formula (II):

• ##STR15## wherein R.sub.1 represents a sulfoalkyl group, a carboxyalkyl group, a sulfoaralkyl group, or a carboxyaralkyl group;
• the alkyl moiety of said groups having up to 4 carbon atoms;
• R.sub.2 represents a substituted or unsubstituted alkyl group or an aryl group;
• R.sub.3 represents --(CH.sub.2).sub.n.sbsb.1 CONH(CH.sub.2)m.sub.1 OH or --(CH.sub.2).sub.n.sbsb.2 O(CH.sub.2)m.sub.2 OH, wherein m.sub.1, m.sub.2, n.sub.1, and n.sub.2 each represents an integer of 1 to 7, m.sub.1 +n.sub.1 and m.sub.2 +n.sub.2 being, however, 8 or less;
• and W represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, or a substituted or unsubstituted phenyl group;
• ##STR16## wherein Z represents a non-metallic atomic group necessary for completing a thiazolidine ring or a 4-thiazoline ring;
• R.sub.4 and R.sub.5 each represents a substituted or unsubstituted alkyl group, an allyl group, or a substituted or unsubstituted phenyl group;
• at least one of said R.sub.4 and R.sub.5 being a sulfoalkyl group or a carboxylic group;
• and R.sub.6 represents a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted phenyl group and developing said image-wise exposed silver halide photographic material with an infectious developer.