Production of reverse reading positive images of a straight reading original

Process for preparing an offset lithographic printing plate comprising a lithographic support carrying a positive working photosensitive resist layer which comprises the steps of:

• (1) photo-exposing to an original, in a camera without a reversing optical means, a negative working photographic material comprising a negative working silver halide emulsion layer on a transparent film support and an antihalation layer either between the emulsion layer and the film support or at the side of said support opposite to that carrying the emulsion layer, said material being disposed with its support facing the camera during said exposure which thus takes place through said support and when said original is a continuous tone original said exposure also being effected through a screen,
• (2) bringing the exposed emulsion layer side of said photographic material into contact with an image-receiving material comprising a transparent support carrying an image-receiving layer containing developing nuclei in the presence of at least one developing agent, an aqueous alkaline liquid for development of the exposed silver halide, and of a silver halide complexing agent to effect the transfer by the diffusion of complexes of unexposed silver halide from the photographic material into the image-receiving layer to form a visible silver image therein,
• (3) separating the exposed photographic material from said image-receiving material,
• (4) contact-exposing said photosensitive resist layer through the silver image carrying image-receiving material from step (3) while the silver image bearing side of said material is in contact with said resist layer, and
• (5) developing said exposed resist layer by selectively removing the exposed areas thereof with a solvent therefor to uncover the lithographic support in these areas.