Method for determining scan line misalignments
AssigneeMustek Systems Inc.
InventorsYu-Fen Tsai, Te-Chih Chang
Life of this patent
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Abstract
A test image has a black bias on a white background. The black bias is a line set at about 45 degrees to the scan lines of a scanner. Boundary points of the scanned bias are found. A regression line is calculated from the positions of the boundary points. Differences in the positions of adjacent boundary points, together with the slope reciprocal of the regression line, are used to determine error values. The error values are compared with a gate value to determine if there are any occurrences of scan line misalignment.
Claims9
A method for determining if an image from a scanner has an occurrence of scan line misalignment, the scanner comprising a housing, a scanning platform upon which is placed a document to be scanned, a scanning module to scan the document, and a driving module to drive the scanning module, the method comprising:
- scanning a document having a test image and collecting corresponding scan line image information from a plurality of scan lines in order, each scan line image having a portion of the scanned image of the test image;
- using a method of searching for a predetermined boundary point to find the position of a boundary point of the test image from the information in every scan line image;
- calculating a regression line from the position of the boundary point;
- calculating discrepancies of corresponding positions of boundary points and the slope reciprocal of the regression line from the image information of adjacent scan lines and determining corresponding error values from every discrepancy and slope reciprocal;
- and
- comparing every error value with a predetermined gate value to determine if the scan line images from the scanner have any occurrences of scan line misalignment.
Dependencies are inferred from the claim text.