Method for correcting vertical alignment error in shuttle scanner

摘要

The reproduced image quality of a shuttle scanner is enhanced by automatically compensating for the scanner's assembly tolerances, using a method for correcting vertical alignment error in a shuttle scanner. The method includes the steps of: (a) initializing a block count of a document to be scanned to a value of N; (b) scanning the Nth block and rasterizing the scanned block into a dot image; (c) shifting each dot of the dot image formed by the rasterized block according to a set of pre-stored correction values; and (d) incrementing the block count and performing the steps (b) through (d) until reaching the end of the document being scanned. The set of pre-stored correction values is produced by the steps of: scanning at least one block of a reference pattern formed on the document to be scanned; comparing the scanned reference pattern with an ideal reference line to calculate a shift value for each dot of the scanned at least one block; and storing the calculated shift values in a memory device. The reference pattern is formed by a vertical line running across at least one block perpendicularly. The memory device installed in the shuttle scanner and programmed at the time of manufacture.