Patent ID: 7021732

Claim:
A method comprising: ejecting ink from a first set of one or more nozzles in a first print head in a staggered print head array to form a first image pattern larger than a single pixel at least partially within an image field located on an intermediate revolving drum; ejecting ink from a second set of one or more nozzles in a second print head in the staggered print head array to form a second image pattern larger than a single pixel at least partially within the image field located on the intermediate revolving drum, the first image pattern and second image pattern forming a composite pattern that is larger than a single pixel within the image field located on the intermediate revolving drum; employing an optical detector having image resolution greater than a single pixel to obtain a measurement of an optical characteristic of the image field located on the intermediate revolving drum; comparing the optical characteristic measurement to a reference optical characteristic to determine whether one of the first and the second print heads in the staggered print head array exhibits an X-axis alignment error; and adjusting the X-axis reference for the print head in the staggered print head array that was determined to exhibit the X-axis alignment error.