This paper revises the algorithm for 2D histogram-based threshold selection by maximum entropy,and proposes one segmentation schema based on revised maximum entropy.The schema divides 2D histogram into four parts:background,target,noise-interrupted background and target,and maximizes the total entropy of the four parts to determine the optimal threshold for image segmentation.This proposed method has 3 advantages:it contains background and target as possible as it can;it is robust to noise;it doesn't consid...