基于HSL颜色空间的自动白平衡算法

Research of Automatic White Balance Algorithm Based on HSL Color Space

为解决自动白平衡算法对所有像素采用单一颜色修正系数存在的低照度色差过大的问题,提出根据HSL颜色空间亮度分量分段计算颜色修正系数的自动白平衡计算方法。计算图像的HSL颜色空间,将亮度分量分成若干段,同一段像素归为一组,通过同一组中饱和度在灰轴附近像素的各颜色分量平均值计算该组的颜色修正系数,根据本组颜色修正系数对该组像素进行颜色修正。应用作者设计的实验电路,采集标准色卡在多种色温下的图像数据,运用HSL灰轴算法、灰度世界算法和全反射理论算法分别对采集的数据进行自动白平衡计算。对比分析每种算法的计算结果与标准色卡的颜色误差。颜色误差分析表明,HSL灰轴算法具有更好的光环境适应能力和颜色还原能力。

A new automatic white balance algorithm was proposed,which could calculate the color modification coefficient according to the lightness in HSL color space.The HSL color space of an image was analyzed in order to divide the lightness into several segments and pixels in each segment were classified into one group.All pixels near to gray axis in the same group were figured out,the color modification coefficient was calculated based on the average value of color components of all pixels,and then the colors of all pixels in this group were modified according to the color modification coefficient.Image data for standard color card in several kinds of color temperature were captured and analyzed respectively according to automatic white balance algorithms,which include HSL gray axis method,gray world method and perfect reflector method.Color error between calculated results of standard cards was analyzed.The result showed that HSL gray axis method has much better light environment adaptability and better color reproduction capability.