Contrast Enhancement of Natural Images Using Histogram Equalization Technique

Image enhancement improves an image appearance by increasing dominance of some features or by decreasing ambiguity between different regions of the image. A number of image contrast enhancement techniques exist to improve the visual appearance of an image. Many images such as medical images, remote sensing images, electron microscopy images and even real life photographic pictures, suffer from poor contrast. Therefore, it is necessary to enhance the contrast of images. Histogram equalization is widely used for contrast enhancement in a variety of applications due to its simple function and effectiveness. However, it tends to change the brightness of an image and hence, not suitable for consumer electronic products, where preserving the original brightness is essential to avoid annoying artifacts. In addition, HE method tends to introduce unnecessary visual deterioration including saturation effect. Preserving the input brightness of the image and keeping PSNR in the desired range are required to avoid the generation of non-existing artifacts in the output image. A number of techniques have been used to overcome its annoying effects. But each technique has its advantages and application areas. This paper presents a new contrast enhancement method based on histogram equalization which aims to better preserve the image quality, preserves better contrast and enriches the image details.