Patent ID: 7708362

Claim:
A method for calibrating one or more printheads, the method comprising: printing a first reference image using a first portion of image forming points of a first printhead; printing a first diagnostic image using a second portion of image forming points of the first printhead, wherein the first portion of image forming points comprises a first segment of a column of image forming points and wherein the second portion comprises a second segment of the column of image forming points on the first printhead and wherein the first reference image and the first diagnostic image at least partially overlap, wherein the first reference image is printed while the first printhead is at a first horizontal position and wherein the first diagnostic image is printed while the first printhead is at the first horizontal position; detecting a first optical density of the combined first reference image and the first diagnostic image; and determining a compensation value based upon the first optical density; printing a second reference image with the first portion of the first printhead while the first printhead is at a second horizontal position; printing a second diagnostic image with the second portion while the first printhead is at a third horizontal position positively offset from the second horizontal position by a first offset distance; detecting a second optical density of the combined second reference image and the second diagnostic image, wherein the compensation value is additionally based upon the second optical density.