基于暗原色先验原理的偏振图像浓雾去除算法

Polarized image dehazing algorithm based on dark channel prior

在浓雾天气下,针对基于常规偏振特性去雾算法去雾效果不理想的特点,提出了一种基于暗原色先验原理的颜色空间转化算法去除偏振图像的浓雾。相比传统的成像技术,偏振图像探测技术在复杂环境下的目标探测和识别处理具有独特的优势,偏振图像通常采用强度图、偏振度图、偏振角图来表征目标的偏振信息。为了达到偏振信息与去雾模型相结合的目的,采用一种颜色空间转化的方法,首先把偏振信息转化到HIS颜色空间对应的亮度、色度、饱和度等各分量中,再把HIS颜色空间映射到RGB空间;其次,结合雾霾图像的大气散射模型用暗原色先验原理求图像的暗通道图;最后,在图像的稀疏先验基础上用softmatting算法细化修正大气传输率。实验结果表明,在能见度很低时,去雾后图像的标准差、信息熵、平均梯度等指标比现有的偏振去雾技术提高很多,该方法能有效增强浓雾天气下图像的整体对比度,提高偏振图像的目标识别能力。

Aiming at not satisfactory defogging effect of the traditional defogging algorithm based on polarized characteristics in heavy fog, a new color space conversion algorithm using dark channel prior for polarization image dehazing was proposed. Compared with the traditional imaging technology, polarization imaging detection technology has remarkable advantages in the target detection and recognition of complex environment. Intensity, polarization degree and polarization angel information are usually used to describe target ＇ s polarization information for polarization images. In order to combine the polarization information and defogging model, a method of color space transformation was adopted. Firstly, the polarization information was converted into the components of the brightness, hue, saturation in Hue-Intensity-Saturation（ HIS） color space and then the HIS color space was mapped to the Red-Green-Blue（ RGB） space. Secondly, the dark channel prior principle was applied to get the dark channel image with the combination of the atmospheric scattering model in haze weather. Finally,the atmospheric transmission rate was elaborated by using softmatting algorithm based on sparse prior of the image. The experimental results show that, compared with the existing polarization defogging algorithm, many technical specifications of defogged images such as standard deviation, entropy, average gradient of the proposed algorithm have been greatly improved in very low visibility conditions. The proposed algorithm can effectively enhance the global contrast in heavy fog weather and improve the identification capability for the polarized images.