Correction method, apparatus, data carrier or system for correcting for unintended spatial variation in lightness across a physical image produced by a xerographic process

摘要

A correction method for correcting unintended spatial variation in lightness across a physical image produced by a xerographic process, the method comprising producing a test image using the xerographic process, measuring a difference between actual lightness and intended lightness across at least part of the test image, and varying the light source level used subsequently in the xerographic process to correct for the measured unintended difference.