BINARIZING DEVICE, BINARIZING METHOD, AND COMPUTER READABLE RECORDING MEDIUM RECORDING PROGRAM FOR MAKING COMPUTER EXECUTE THE BINARIZING METHOD

摘要

PROBLEM TO BE SOLVED: To stably binarize a density image of a document by selecting a suitable binarizing threshold value at the time of registering and checking the document. SOLUTION: A minimum value detecting portion 13 detects plural minimum values positioned near a prescribed density value of a density histogram received from a density histogram producing portion 12. A binarizing threshold value selecting portion 14 selects the density value of the minimum value that becomes the smallest value as a binarizing threshold value, from the plural minimum values detected by the minimum value detecting portion 13.