A New Approach to the Photographic Problems of Colour Photo-litho.

The photo-litho process, using a cross-line screen, normally gives poor tone reproduction unless a considerable amount of handwork is introduced at some stage. In color reproduction work, the well-known errors due to unwanted special absorptions of the printing inks are superimposed upon those caused by poor tone-reproduction characteristics. A process has been developed by which screen positives are made directly from color originals. During the reversal process, both tone reproduction and color corrections are introduced. The theory and practice of this process are outlined.