Block-DCT based homomorphic filtering algorithm for color image enhancement
Minghong Xie · Jisuanji gongcheng yu sheji · 2013
For the color image of non-uniform illumination,because the traditional homomorphic filtering doesn't fully take into account the local characteristics of the image,the local contrast enhancement effect of the image after homomorphic filtering is not satisfactory.To this end,combined with the advantages of the DCT,the homomorphic filtering algorithm based on block discrete cosine transformation(DCT) is proposed,which can provide a better enhancement effect on the local contrast.In order to eliminate the block effect caused by block filtering,the method of block effect elimination based on overlapping blocks is pre-sented.Meanwhile,in order to retain the color information of the original image,the image is converted from the RGB color space to HSV color space.The only luminance component is enhanced by the homomorphic filtering based on block-DCT and block effect removal.The hue and saturation components are invariant.The experimental results show that this method is not only effective in improving the impact of the non-uniform illumination of the image,and to maintain a good image color and clearer image details.The performance of homomorphic filtering based on block-DCT is superior to traditional one.