Real Color Image Enhanced by Illumination - Reflectance Model and Wavelet Transform

Because the color restoration functions of real color image enhancement are greatly at random and not proved, and the enhanced real color images which are based on illumination-reflectance model have the loss of details and the ´halos´, we proposed a new algorithm to overcome these disadvantages. Firstly, we transform the real color image from RGB space to HSV space which is approximately orthonormal between color and value, and keep the color of image. Secondly, the illumination and the reflectance of value are separated by homomorphic decomposition based on illumination-reflectance model. We have discovered that the high dynamic range of image including high bright lights is mainly caused by the reflectance. Thirdly, the details of reflectance are preserved by wavelet transform. Lastly, the dynamic range of reflectance is compressed by Butterworth filtering. Experiments show that the color of image enhanced is not obviously distorted, the preservation of the details is good and the ´halos´ is effectively restrained. Real color image enhanced by the algorithm is much better than the multi-scale Retinex´s with color restoration (MSRCR).