Example-Based Color Transfer Function Design

Volume rendering is a color-blending process, thus users often find nontrivial to directly edit color transfer function for getting expected volume rendering results. In order to make the process more intuitive, this paper proposes an example-based color transfer function design method. A colorization method in 2D image processing is adopted to colorize the initial volume rendering image with the same color style as the example. Then the color at each voxel in 3D space is inversely calculated based on volume rendering process. An optimized framework is developed to find the optimal color transfer function to produce the result which is the most similar with the colorized image and thus consistent with the example image. The example image can be any images with expected colors. Compared with traditional transfer function design methods, this method takes advantage of human perception about images, simple and intuitive. It eliminates cumbersome handwork. Experimental results demonstrate that this semi-automatic method is effective and convenient.