Patent ID: 8662625

Claim:
A method for analyzing image data of a test pattern generated by a printer comprising: identifying, with reference to a first threshold and a second threshold, a process direction position for each row of dashes in a plurality of rows of dashes in image data of a test pattern printed on an image receiving member, the test pattern being formed by each printhead in a plurality of printheads in a printer forming at least one dash in each row of dashes in the plurality of rows of dashes; identifying a center of each dash in a cross-process direction; identifying an inkjet that formed each dash in the plurality of rows of dashes; and identifying a cross-process direction position for one printhead in the plurality of printheads in the printer with reference to the identified cross-process direction centers of dashes formed by the identified inkjets in the one printhead; the identification of the process direction position comprising: convolving a plurality of sections of a single scanline of the image data generated by an optical detector in the cross-process direction with two periodic functions each having a period corresponding to spacing between dashes in one row of dashes; summing a first square of the convolution for each of the two periodic functions in each of the plurality of sections of the single scanline; convolving each scanline in a successive plurality of scanlines in the image data generated by the optical detector in the process direction from the single scanline in response to the sum of the first square of the convolution corresponding to the image data of the single scanline being greater than the first threshold; summing a square of the convolution corresponding to the image data of each scanline in the successive plurality of scanlines until the sum of the square of the convolution of the image data corresponding to a final scanline in the successive plurality of scanlines is less than the first threshold; and identifying that image data corresponding to the successive plurality of scanlines between the single scanline and the final scanline correspond to a single row of dashes on the image receiving member in response to the sum of the square of the convolution for image data corresponding to at least one of the successive plurality of scanlines being greater than the second threshold, the second threshold being greater than the first threshold.