Patent ID: 6137541
Filing Date: 2000-10-24
Classification: H04N

Abstract:
An image processing apparatus wherein image data, having a brightness range in designated gradations and including at least a background and meaningful information in the background, is converted to image data in n gradations (n>2), with n differing from said designated gradations, comprising:a parameter computation unit that determines the cumulative frequency distribution of the pixels for each brightness from the image data having said brightness range in the designated gradations, and that determines the average brightness and standard deviation of the part wherein the background is predominant from the cumulative frequency distribution;a threshold value computation unit that determines a first threshold value, that is an indicator of the boundary between the background and said meaningful information, on the basis of said average brightness and standard deviation of the part wherein the background is predominant as determined by said parameter computation unit, and that determines second through n-1st threshold values corresponding to said meaningful information on the basis of said first threshold value; andan n value conversion process unit that performs an n value conversion process on said image data using the first through n-1st threshold values determined by said threshold value computation unit.