Correcting cross-track errors in a linear printhead

A method for correcting cross-track position errors in a digital printing system having a linear printhead, the linear printhead extending in a cross-track direction and including an array of light sources for exposing a photosensitive medium, comprising:

• a) providing digital image data for a test target including a plurality of alignment marks positioned at predefined cross-track positions;
• b) printing the test target using the digital printing system to provide a printed test target;
• c) using a digital image capture system to capture an image of the printed test target;
• d) using a data processing system to automatically analyze the captured image to determine a measured position for each of the alignment marks;
• e) comparing the measured positions for the alignment marks to reference positions to determine measured cross-track position errors;
• f) determining a cross-track position correction function responsive to the measured position errors, wherein the cross-track position correction function specifies cross-track position corrections to be applied as a function of cross-track position;
• g) storing a representation of the cross-track position correction function in a digital memory;
• h) receiving digital image data for a digital image to be printed by the digital imaging system, wherein the digital image includes a plurality of image lines extending in the cross-track direction;
• i) determining corrected image lines by resampling the image lines of the digital image responsive to the stored representation of the cross-track position correction function;
• and
• j) printing the corrected image lines using the digital printing system to provide a printed image with reduced cross-track position errors;
• wherein the linear printhead includes a plurality of individual light source chips, each including a plurality of light sources, and wherein alignment marks are positioned in proximity to boundaries between adjacent light source chips.

A method for correcting cross-track position errors in a digital printing system having a linear printhead, the linear printhead extending in a cross-track direction and including an array of light sources for exposing a photosensitive medium, comprising:

• a) providing digital image data for a test target including a plurality of alignment marks positioned at predefined cross-track positions;
• b) printing the test target using the digital printing system to provide a printed test target;
• c) using a digital image capture system to capture an image of the printed test target;
• d) using a data processing system to automatically analyze the captured image to determine a measured position for each of the alignment marks;
• e) comparing the measured positions for the alignment marks to reference positions to determine measured cross-track position errors;
• f) determining a cross-track position correction function responsive to the measured position errors, wherein the cross-track position correction function specifies cross-track position corrections to be applied as a function of cross-track position;
• g) storing a representation of the cross-track position correction function in a digital memory;
• h) receiving digital image data for a digital image to be printed by the digital imaging system, wherein the digital image includes a plurality of image lines extending in the cross-track direction;
• i) determining corrected image lines by resampling the image lines of the digital image responsive to the stored representation of the cross-track position correction function;
• and
• j) printing the corrected image lines using the digital printing system to provide a printed image with reduced cross-track position errors;
• wherein the cross-track position correction function is quantized to integer cross-track position corrections.