Image Enhancement Using Nonsubsampled Contourlet Transform

This paper presents a novel technique of image Enhancement which can be widely used in medical and biological imaging to improve the image quality. The principle objective of enhancement is to process an image so that the result is more suitable than the original image for a specific application. Image enhancement enhances weak edges or weak features in an image while keeping strong edges or features. All existing methods of image enhancement decompose images in a separable fashion, and thus cannot use the geometric information in the transform domain to distinguish weak edges from noises. Therefore, they either amplify noises or introduce visible artifacts, when they are applied to noisy images. The NonSubsampled Contourlet transform built upon NonSubsampled pyramids and NonSubsampled directional filter banks can provide a shift invariant directional multi resolution image representation. The geometric information is gathered pixel by pixel from the NonSubsampled Contourlet Transform coefficients. The proposed method achieved better enhancement results than the wavelet based methods of enhancement.