Litho

From Nikonians Wiki

Litho is a photographic process designed for preparing negatives for commercial offset litho print. Litho film only records black and white, with no gradations, and is typically supplied in rolls capable of producing SRA2 cut sheets. In the past, a litho camera would be used to photograph the layout, referred to as 'camera ready artwork', which would then be rapidly developed in a darkroom, often by an automated process. The litho negative or positive could be adjusted by hand, often using a razor-blade and Rotring pen. The final film would then be used to make printer's plates.

Because litho only recognises black and white, photographs would first have to be screened, which turns the continuous tone image into a half-tone image made up of black and white dots of various sizes. Colour images would have to be screened and separated into CMYK.

Under current technology, a litho film would be produced by an imagesetter device, and developed as before. In principle, this can still be worked on with a pen and razor-blade, but, in practice, the file would be re-edited in a Desktop publishing application and re-output. Plates are made as previously.

A digital press does not require plates at all, and the output is sent direct from computer to press, thereby eliminating litho from the process.

Litho film can be placed in a normal film camera, for a particular black and white (not monochrome) effect, or litho can be used as an internegative. More commonly, litho can be applied as a special effect in postprocessing.

• This page was last modified on 28 December 2008, at 14:24.
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