1. A method for detecting motion quality error of printed documents in a printing system comprising: printing a document having text lines, each text line comprising a plurality of characters; scanning the printed document to generate a scanned image; detecting positions in a process direction of the printing system of one of text lines and characters in the scanned image; determining position errors in the process direction in the printed document based on the detected positions in the scanned image; determining at least one motion quality defect of the printing system in the process direction based on the determined position errors; and initiating an activity associated with said printing system in response to a motion quality error having been determined.