Contrast Enhancement Techniques for Images- A Visual Analysis

Image enhancement is one of the most interesting and visually appealing areas of image processing. It involves operations such as enhancing contrast, reducing noise for improving the quality of the image. This paper presents an analysis of the mathematical morphological approach with comparison to various other state-of-art techniques for addressing the problems of low contrast in images. Histogram equalization (HE) is one of the common methods used for improving contrast in digital images. This method is simple and effective for global contrast enhancement of images but it suffers from some drawbacks. Contrast Limited Adaptive Histogram Equalization (CLAHE) enhances the local contrast of the images without the amplification of the noise. Morphological Contrast enhancement is performed using the white and black top-hat transformation. It can be performed at a single scale or at multiple scales of the structuring element. The structuring element can be of various shapes and sizes.