Abstract: A document to be scanned is corner referenced on a transparent platen, with the document's image facing down. The platen defines an X-Y coordinate system matrix. A moving line of light extends in the X direction and illuminates the document's image, line by line, as the line of light moves in the Y direction. The line of light that is thus reflected from the document is sensed by a linear CCD sensor array having a large number of individual sensor cells arranged in a line that effectively extends in the X direction. Each cell of the CCD array defines an individual pixel (PEL) within the line of light that is reflected from the document. A reflection target is located at a known position relative to the platen's referencing corner, to be scanned prior to scanning the document.