THRESHOLD VALUE CALCULATION DEVICE

摘要

PURPOSE:To calculate a threshold value to be used in a CCD inspection device to effectively detect the picture irregularity of a CCD image receiving element. CONSTITUTION:A histogram computing part 45 computes the histogram of picture element values which are the output values of picture elements, a block value computing part 46 divides plural picture elements into blocks by each prescribed number and computes a block value which is the average value of the picture element values of the picture elements inside the block and a block histogram computing part 47 computes the histogram of the block values (block histogram). A scale correction part 48 corrects the scale of the block histogram or the histogram of the picture element values and equalizes the scales of both, a difference computing part 50 compares the block histogram and the histogram of the picture element values whose scales are equalized and a threshold value selection means 60 selects the threshold value by using the feature point of the output of the difference computing part 50.