黑白图像的彩色化是图像处理领域一个活跃的、有挑战性的研究课题。在总结现有图像彩色化方法的基础上，分析了彩色化由局部向全局扩展的本质，进而提出了一种通过求解拉普拉斯方程实现颜色扩展的彩色化方法。为提高边界定位能力，设计了加权形式的差分方案。与同是采用偏微分方程的Saprio彩色化方法相比，该方法与其控制颜色扩展的机制不同，图像彩色化效果要明显优于Saprio方法。

Colorization of grayscale image is in general an active and challenging area of research in image processing.In this paper,current colorization algorithms are summarized and the principle of color propagation is analyzed.Then a colorization algorithm based on Laplace equation is proposed.In order to determine the boundary accurately,a weighted difference scheme is applied.In contrast with Saprio's colorization algorithm which is also a partial differential equation based method,the principle of color propagation in our algorithm is different.Furthermore,our algorithm can achieve more vivid colorized result.