A robust technique for contrast enhancement using Quaternionic Wavelet Transform with natural brightness

In this paper we propose a new methodology for contrast enhancement (CE) and edge preservation of an image using Quaternionic Wavelet Transform (QWT) and Singular Value Decomposition (SVD). Although there are many techniques like Global histogram equalization (GHE), Local histogram equalization (LHE) and other singular value based enhancement techniques, these methods are not robust as it fails to enhance very poor contrast images. By using Quaternionic Wavelet Transform the quality of the image is better enhanced compared to other wavelet transforms. QWT provides very good shift invariance and directionality than DWT. In addition to that the proposed technique maintains the brightness of the image and preserves the edges of the image with relatively fewer artifacts.