Printer with cross-track position error correction

A digital printing system incorporating cross-track position corrections, comprising:

• one or more printing subsystems, each printing subsystem including a linear printhead extending in a cross-track direction including an array of light sources for exposing a photosensitive medium;
• a data processing system;
• a digital memory for storing a cross-track position correction function;
• and
• a program memory communicatively connected to the data processing system and storing instructions configured to cause the data processing system to implement a method for determining a cross-track position correction function for at least one printing subsystem, wherein the method includes:
• 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) automatically analyzing 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 the 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;
• and
• g) storing a representation of the cross-track position correction function in the digital memory;
• wherein the digital printing system is adapted to print digital images using a printing process that includes:
• i) 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;
• ii) 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
• iii) printing the corrected image lines using the one or more printing subsystems 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;
• and
• wherein the representation of the cross-track position correction function stored in the digital memory includes the cross-track positions and transition direction of transitions in the cross-track position correction function.

A digital printing system incorporating cross-track position corrections, comprising:

• one or more printing subsystems, each printing subsystem including a linear printhead extending in a cross-track direction including an array of light sources for exposing a photosensitive medium;
• a data processing system;
• a digital memory for storing a cross-track position correction function;
• and
• a program memory communicatively connected to the data processing system and storing instructions configured to cause the data processing system to implement a method for determining a cross-track position correction function for at least one printing subsystem, wherein the method includes:
• 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) automatically analyzing 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 the 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;
• and
• g) storing a representation of the cross-track position correction function in the digital memory;
• wherein the digital printing system is adapted to print digital images using a printing process that includes:
• i) 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;
• ii) 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
• iii) printing the corrected image lines using the one or more printing subsystems 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;
• wherein the representation of the cross-track position correction function stored in the digital memory includes the cross-track positions and transition direction of transitions in the quantized cross-track position correction function.