APPARATUS AND METHOD OF STRETCHING HISTOGRAM FOR ENHANCING CONTRAST OF IMAGE

摘要

A histogram stretching device for improving the contrast of an image and a method thereof are provided to improve the stretching effect by removing the saturation area of an inputted image and perform the stretching for an image having single color without the distortion. A histogram calculation unit(11) produces a histogram which indicates the frequency of each image level in pixels within an input image in which the histogram stretching will be performed. A histogram analysis unit(12) calculates the cumulative distribution of frequencies corresponding to each image level from the calculated histogram. A linear function application unit(13) calculates the modified maximum extension level and the modified minimum extension level by mapping the maximum value and minimum value of an image level region to a linear function which is linearly changed between the maximum extension level and minimum extension level preset to expand the histogram by the histogram stretching.