Hue Preserving Enhancement Algorithm Based on Wavelet Transform and Human Visual System

This paper proposes a new method for enhancing the contrast as well as brightness of color images, based on orthogonal D4 Wavelet transform human visual system and also considers distinction between the background and foreground of the images. The RGB (Red, Green, and Blue) values of each pixel in a color image are converted to HSI (Hue, Saturation, and Intensity) value. On the S components of the color image, the orthogonal D4 Wavelet transform is applied in the appropriate blocks. It can be detected by suitable edge detector. The orthogonal D4 Wavelet transform decomposes the S component into detail and approximate components. Then the contrast as well as brightness enhancement on the approximate component based on the human visual system is applied. For I component histogram equalization is applied. IWT is applied on the detail and modified approximate component for the selected block. The old H, modified S and modified I, are then converted into the RGB color space. The effectiveness of the proposed method is demonstrated experimentally.