Patent ID: 8721033

Claim:
A method for analyzing image data of a test pattern generated by a printer comprising: generating with an optical sensor image data of a test pattern having a plurality of rows of dashes, the test pattern being formed on an image receiving member by each printhead in a plurality of printheads within a printer that form the test pattern with at least one dash in each row of dashes in the plurality of rows of dashes; identifying a process direction position for each row of dashes in the plurality of rows of dashes in the image data of the test pattern on the image receiving member; identifying a center of each dash in a cross-process direction; identifying an inkjet ejector that formed each dash in the row of dashes; identifying a process direction position for each printhead in the printer by convolving a portion of the image data of the test pattern that corresponds to a response of an optical detector to light reflected by the image receiving member with a cosine function and a sine function having a period corresponding to spacing between dashes in a row, summing a square of each convolution, and identifying the position of the dash as corresponding to the position where the sum of the squares of the convolutions is greater than a threshold; identifying a cross-process displacement for each column of printheads; identifying a stitch displacement in the cross-process direction between neighboring printheads in a print bar unit that print a same color of ink; and operating an actuator to move at least some of the printheads in the printer with reference to the identified process direction positions, cross-process displacements, and the identified stitch displacements.