Lithographic reproduction original classification and color separation tone curve adjustment

摘要

An original to be lithographically reproduced is classified according to density distribution into one of a plurality of classes established on the basis of various high quality standard printed reproductions by comparing the density distribution patterns of the original and the standard reproductions. The patterns indicate relative frequency of density values in the entire density range. After being classified, the original is reproduced utilizing a standard color separation tone curve for a scanner that corresponds to the compared and selected standard reproduction. Alternatively a reference tone curve based on a grey scale may be used with a correction according to the difference between the reference tone curve and the standard tone curve. Also the reference tone curve may be corrected with the difference between the original density distribution pattern and the selected standard density distribution pattern. An apparatus for use in the processes is also disclosed.