复杂光照下的两步法颜色恒常性增强

Color constancy enhancement in two steps under variable illumination

根据视觉信息处理的分模块性原理,研究了复杂光照下的颜色恒常性,给出了一种两步法颜色恒常彩色图像增强算法。利用边缘附近像素估计原图像的偏色信息,采用白平衡的方法对偏色图像进行偏色纠正。然后,根据RGB颜色空间三分量的颜色相关性特点,获取亮度增益曲面并对彩色图像的RGB三分量进行同比增强得到最终的彩色图像。在SFU数据库进行了实验,结果表明该算法的对比度是原图的4倍以上,且亮度改变适中。该算法克服了传统颜色恒常性的不适定问题,对于存在偏色、低照度等复杂光照下的图像均能较好地保持颜色的恒常性,同时能有效提升图像的对比度和亮度。

According to the module principle of visual information processing, the color constancy under variable illumination is studied and a novel color constancy image enhancement algorithm in two steps under variable illumination is presented. After estimating the color offset of an original image using the pixel near edges, the color offset is corrected with white balance. Then, based on the correlation characteristics of three components in RGB color spaces, the RGB three components of the color image are enhanced at the same proportion by brightness gain curved surface to ensure the hue to be a constance. The experiment on the SFU database indicates that the contrast of the processed image is four times as high as that of the original image, and the brightness change is suitable. The algorithm overcomes the ill-posed problem of traditional color constancy algorithm and can better maintain the color constancy for the images under variable illumination with color offsets or lower illuminating, and can enhance effectively the contrast and brightness.