1. A method for aligning multi-channel digital image data for a digital printer having a plurality of printheads, each printhead printing digital image data for a particular channel, comprising: receiving one or more scanned test patterns formed by using an imaging device to capture an image of a test pattern printed using the digital printer, the test pattern including test pattern indicia printed using individual printheads; analyzing the scanned test patterns to detect locations of the printed test pattern indicia; determining reference test pattern indicia locations; designating at least one of the printheads to be a non-reference printheads; determining one or more spatial adjustment parameters for each of the non-reference printheads responsive to the detected locations of the corresponding printed test pattern indicia and the reference test pattern indicia locations; receiving multi-channel digital image data for a multi-channel digital image, the multi-channel digital image data including image pixels having pixel values; modifying the digital image data for the channels associated with the non-reference printheads in accordance with the determined spatial adjustment parameters, wherein the modification of the digital image data includes: designating an input pixel neighborhood within which an image pixel should be inserted or deleted based on the determined spatial adjustment parameters; comparing the image pixels in the input pixel neighborhood to a plurality of predefined pixel patterns and identifying a matching pixel pattern; and determining a modified pixel neighborhood having either one more image pixel or one less image pixel than the input pixel neighborhood, wherein the pixel values of the image pixels in the modified pixel neighborhood are determined responsive to the matching pixel pattern; and printing the modified digital image data using the digital printer; wherein the modification of the digital image data provides improved alignment between image content printed with the reference and non-reference printheads.