Neutral Gray Adjustment in Printer ICC Profiles

摘要

Neutral gray balance is very important in printing black and white images and printing images that have gray or near gray contents. Accurate gray balance is often difficult to achieve by ICC profiling software packages, especially by commercial software packages designed for users with little knowledge in color science. Furthermore, neutral gray may be judged differently by different individuals. In order to solve these problems, we developed different mechanisms to improve and to modify the neutral gray balance in printer ICC profiles. In this paper, a method to modify the transformation of the neutral gray balance for printer ICC profiles is presented. A colorimetric table, which is derived from the AToB1 tag and the white point tag or derived from a colorimetric data set measured from a near-gray target, is applied to recreate the neutral gray points in BToAi tags. The neutral gray point in a~* and b~* is determined by color appearance modeling or by a user for personal preference. Different a~* and b~* values for different lightness can be supplied to compensate the inaccuracy in AToB1 tag or color shift of the printer. To achieve highly accurate neutral gray balance, a target surrounds the neutral gray from white to black is printed for neutral gray balance calibration. Black adaptation is also taken into account to compensate the chrominance difference between the white point and the black point.