Global Color Saliency Preserving Decolorization

The process of transforming a color image with three channels to a single channel grayscale image is called decolorization, which will unavoidably accompany with the information loss. In this paper, we propose a method to obtain a grayscale image which best preserves the global saliency of the color image. First, we convert the color image to the YUV color space, which separates the luminance and chrominance channels, and conduct parametric linear mapping on Y,U,V channels, through selecting different parameters to get different candidate grayscale images. Then, we compute the global contrast based saliency maps of the color image and candidate grayscale images. Finally, we use the Normalized Cross-Correlation metric to select the grayscale image whose saliency map is the most similar to that of the color image as the wanted decolorization result. The experiment results show that our method retains part of the chrominance information, prevents the contrast degradation in the isoluminance colors, and the global saliency preserving purpose reduces the abrupt change or distortion around the edge areas.