Patent ID: 7406193
Filing Date: 2008-07-29
Classification: G06T

Abstract:
1. An image processing method of making luminance correction on the basis of a luminance histogram showing distribution of a luminance level of image data in which an image is expressed by a numerical value, comprising the steps of: obtaining a luminance average value in said luminance histogram, a luminance standard deviation indicative of a degree of dispersion of luminance distribution from said luminance average value, and a peak distance value which indicates a longest distance between peaks is calculated in said luminance histogram in the case where plural peaks exist, so that plural distances between respective peaks exist; comparing a distribution discrimination value which can discriminate whether a distribution deviation of the luminance level exists on a low luminance side or a high luminance side in said luminance histogram or not with the obtained peak distance value, and comparing a halftone presence/absence discrimination value which can discriminate whether the distribution deviation of the luminance levels does not exist in a halftone in said luminance histogram or not with the obtained standard deviation, thereby discriminating whether said image is a backlight image or not on the basis of results of said comparisons; and comparing each of said luminance average value and said luminance standard deviation by using an exposing state discrimination value which can discriminate the exposing state, thereby discriminating an exposing state of an image other than the backlight image.