Thresholding method for segmenting gray scale image, method for determining background concentration distribution, and image displacement detection method

摘要

In a thresholding method for segmenting gray scale image which is less dependent on the concentration distribution of the input image, the threshold in determined as a zero-cross point of a histogram difference between the concentration histograms for the gray scale image within the window at a window position at which the window contains more high concentration region and at a window position at which the window contains more low concentration region. Also, in a method of determining a background concentration distribution from an image having an arbitrarily distributed pattern, the background concentration level is determined as a peak concentration or a mean value concentration of a low concentration section of the histogram difference of the concentration histograms for two associated windows. Also, in an image displacement detection method capable of detecting a displacement of a pattern in a two dimensional image accurately by using only a one-dimensional pattern matching without any period mismatching error even for an image of a repetitious pattern, the discplacements in the vertical and lateral direction which are locally minimum and for which a discrepancy in an oblique direction is minimum are selected as the actual displacements.