The invention relates to an image enhancement evaluation algorithm based on human visual characteristics. The gray scale difference of adjacent pixels in an image reflects basic information of the image, and human eyes are difficult in distinguishing the gray scale difference smaller than critical visible deviation. The higher the gray scale difference proportion which can be distinguished by human eyes is, the higher the image quality is. By using a certain image enhancement algorithm, if the gray scale difference proportion which can be distinguished by human eyes in the processed image is increased relative to the original image and the processed image has good correlation relative to the original image, the implementation of the image enhancement algorithm is beneficial to image observation; otherwise, the image enhancement algorithm is unbeneficial to image observation. The invention provides an evaluation index for the image enhancement algorithm, and can assist test personnel in debugging some configuration parameters in the enhancement algorithm or comparing the virtue or defect degrees of several enhancement algorithms.