Abstract
This paper is concerned with the problem of automatic colorization of grayscale images via color transfer. Some deficiencies of Welsh's colorization algorithm are pointed out and analyzed. Then, a new colorization algorithm is proposed, which uses a new similarity function and a new search strategy for pixel matching. The new function incorporates both the luminance information and chromatic values of previously colorized neighboring pixels. The intrinsic space clustering property of an image is taken into account in the strategy by using Hilbert filling curve scanning order. Experimental results showed that the proposed algorithm outperforms Welsh's algorithm in both colorization effect and computational complexity. Moreover, the proposed similarity function and search strategy can easily be embedded into other colorization algorithms to improve their performance.