Technique for use in conjunction with an imaging system for providing an

Abstract

Apparatus, and associated methods employed therein, for objectively providing an accurate appearance match between two depictions of a common images produced by two imaging systems (e.g. a target image (170) produced by one such system (160), e.g. a press sheet (178) generated by a printing press (168), which is to be matched by a replica image (150) produced by another such system (140), e.g. a proof (153) generated by a direct digital color halftone proofing system (143)) and thereby calibrate the performance of one imaging system, e.g. the proofing system, to that of the other system, e.g. the printing press. Specifically, measurement data, such as illustratively colorimetric CIELAB L*a*b* measurements, is obtained for the same portions of the press sheet and proof. This data is acquired in or transformed into a color space which encodes color information in a pre-defined manner that approximates human color perception. Thereafter, through use of a pre-determined model of the, e.g., proofing system, incorporated into pre-defined matching principles which objectively and quantitatively define an accurate appearance match between the depictions produced by both systems, operational settings for the proofing system, such as solid area densities and tint dot areas, are determined which will calibrate the response of the proofing system to that of the press. Consequently, tone and color rendition produced by the proofing system is modified to provide an accurate appearance match to that obtained, from a common image source, on the press, given judgmental color preferences of a human observer and performance limitations of the proofing system.