Method and apparatus for thresholding images

摘要

An adaptive thresholding filter generates multiple threshold values for use in thresholding the multi-bit pixels of a gray-scale input image. Each threshold value is based on a current white reference value and a current black reference value. The current white reference value is selected based on a comparison of the current image pixel to a white reference comparator value generated by applying a white reference aging function to a prior white reference value. The current black reference value is selected analogously using a black reference comparator value and a black reference aging function.