Markless color control in a printing press

Abstract

The invention provides a method for controlling a plurality of ink control devices on a printing press, wherein the press operates to repetitively print an image on a substrate. The ink control devices each control the amount of ink supplied to a respective ink key zone on the substrate. The method includes the step of measuring color values for a plurality of areas of a selected image printed on the substrate to produce an acquired image array. Next, the acquired image array is aligned with a target image array comprised of target color values for the plurality of areas. The acquired image array is compared to the target image array on a pixel by pixel basis. A matrix equation is determined that links ink control device adjustments to changes in color values of the image printed on the substrate via sensitivity factors for each of the plurality of pixels. A least squares solution to the matrix equation is obtained to determine ink adjustments for each ink key zone. The ink adjustments are communicated to the ink control devices.

Dependencies are inferred from the claim text.