针对表观检测系统中照明效果评价和优化较困难的问题，分析了印刷电路板表观图像及其在三维色彩空间中的像素值分布，提出基于三维色彩空间的照明效果评价方法，以量化的色彩分离程度、像素值波动程度和缺陷色彩偏离程度来建立评价函数。实验结果表明，此方法可有效地量化照明效果并符合人眼视觉感受，量化的精度优于1%，根据评价函数进行照明优化可达到对于该电路板的适配照明效果。本方法也可用于类似的表观缺陷检测，如印刷质量检测和塑料产品缺陷检测。

Assessment and optimization of illumination are difficult issues in automatic visual inspection. After analyzing the images of visual inspection of printed circuit boards and their pixel value distribution in three-dimensional color space, an illumination assessment method is proposed. This merit function is based on quantitative analysis of Euclidean distance of color in red-green-blue (RGB) space, fluctuation extent of pixel value and deviation of defect color. The experimental results show that this method is suitable for evaluating the illumination effect and complies with subjective feeling of human visual system. It is also shown that the precision is better than 1%. An illumination optimization experiment is performed and the optimum lighting effect is obtained based on the merit function. This method can be applied to other visual inspection areas, such as color print quality inspection and plastic product defects inspection.