Survey on Various Image Contrast Enhancement Techniques

In this paper a survey on various image contrast enhancement techniques has been done. Colour image enhancement plays an important role in digital image processing. Contrast enhancement is an optimization problem and is done for the images which are experiencing poor quality. Poor quality on images is due to various factors like environmental lighting conditions, defects in photographic devices etc. Therefore image contrast enhancement is important in order to improve the human acceptance rate. Most of the papers are based on histogram equalization technique and its extensions. Histogram equalization is a contrast enhancement technique based on histogram of the image. Each technique has got its own advantages as well as disadvantages. Various contrast enhancement techniques have been proposed by different authors as an extension of the traditional histogram equalization. They are power constrained contrast enhancement, dynamic range compression, colour model conversion, gamma correction and channel division methodologies. Several recent papers are being surveyed under each technique.