为了解决低照度环境引起的彩色图像退化问题, 提出一种新的低照度图像增强算法。首先在YUV色彩空间下采用对数图像处理(LIP)运算对彩色图像的亮度分量进行调整, 以提高暗调区的亮度和对比度, 然后选取适宜的参数, 利用限制对比度自适应直方图均衡化(CLAHE)对亮度分量进行二次增强, 以获得更好的增强效果, 最后根据亮度增益, 利用线性运算恢复增强图像的色彩信息。实验结果表明, 该算法能够有效地提高低照度彩色图像的视觉质量, 细节鲜明突出, 色彩真实自然, 同时也避免了过度增强, 噪声放大等现象。

To solve the degradation of color images caused by low illumination condition, a novel algorithm to improve the visibility of low illumination images is proposed. At first, the operation based on logarithmic image processing (LIP) model is adopted to regulate the luminance component calculated from the color image in YUV color space so that the brightness and contrast of low level gray regions of the image can be increased accordingly. And then, the contrast limited adaptive histogram equalization (CLAHE) with suitable parameters is introduced to modify the luminance component to improve the quality of image enhancement further. At last, a linear color restoration process based on the luminance gain is used to determine color values of the enhanced image. Experimental results show that the proposed algorithm is more effective and practicable, and the enhanced image can achieve an excellent global visual effect with clear details and natural colors, while avoiding excessive enhancement, noise enlargement and so on.