Patent ID: 7800777

Claim:
A method comprising: printing a first series of control patches with a first marking engine; printing a second series of control patches with a second marking engine; measuring first relative reflectance values of the patches printed with the first marking engine and second relative reflectance values of the patches printed with the second marking engine with respective first and second engine response sensors; calculating first patch error values based on comparing the relative reflectance values of the first patches and first target values for the first marking engine and calculating second patch error values based on comparing the relative reflectance values of the second patches and the second target values for the second marking engine; calculating a relative engine-to-engine error based on at least on a difference between the calculated first patch error values and the calculated second patch error values; decomposing the engine to engine error into lightness and contrast components if the relative engine-to-engine error is greater than a first threshold value; and based on the decomposition, determining adjustment of at least binary values of a digital image so that print density of a first marking engine output substantially matches print density of a second marking engine output including: determining if the contrast component is present, adjusting the lightness component of at least one of the first and second marking engine if the contrast component is not present, and adjusting at least a contrast component in at least one of the first and second marking engines if the contrast component is present.