METHOD FOR DETERMINING BACKGROUND GRAY LEVELS OF DOCUMENT

摘要

PROBLEM TO BE SOLVED: To automatically determine the image background gray levels of a scanned document with a small calculation amount. SOLUTION: This method determines, the background gray levels of a scanned document. A histogram of gray levels is generated from a document sampling window, and the histogram is smoothed. A rough curve of the smoothed histogram is determined, the standard deviation of the curve is determined, and a gain of the document and a maximum gray level of the histogram are determined, based on the standard deviation, and the background gray levels of the document is decided based on the gain.