Survey on Image Enhancement

The contrast enhancement method frequently play crucial role in image processing. Image enhancement is the task to process an image so that the result is more suitable than the original image for specific applications. The alteration usually requires interpretation and feedback from a human evaluator of the output resulting image. Image enhancement is to improve the image quality so that the resultant image is better than the original image for a specific application or set of objectives. The channel division technique enables operation on the content of the image and therefore content such as edges and other subtle information can easily be enhanced. This paper also presents a review of various methods for contrast enhancement. The channel division technique is based on the analysis of the content in several regions and create transformation function for separate region. This paper also present method which divides the image into sub image then perform enhancement. The major difference among the methods in this family is the criteria used to divide the input histogram. Brightness preserving Bi-Histogram Equalization(BBHE),weighted mixture of global and local transformation, sub block histogram equalization, recursively separated method are based on the split image in its sub images then perform enhancement. In image dependent brightness preserving method curvelet transform function used. Brightness preserving dynamic histogram equalization is an extension of histogram equalization.