针对多尺度Retinex 算法(MSR)计算复杂度过高的缺陷,本文提出了模拟人眼视觉特性的Retinex 图像对比度增强方法。该方法根据Retinex 计算模型分离彩色图像的照射分量和反射分量,并引入非线性变换函数对其进行修正。基于对数变换的非线性函数拉伸图像照射分量,改善了全局视觉效果,再利用考虑人眼灰度分辨能力的变换函数对反射分量值进行调整,从而改善了图像局部对比度。实验结果表明,算法直接在RGB 彩色空间和其它分离色度亮度的彩色空间的处理效果都很好,没有出现明显的彩色失真现象,处理速度也快于MSR 算法。

Aiming at drawback of high computation complexity of multi-scale Retinex, an algorithm for contrast enhancement of image which simulates visual characteristics of human eyes is proposed. According to Retinex model, the image is separated into illumination and reflection component. And two nonlinear transformation functions are introduced to modify illumination and reflection components of the image respectively. And the global contrast enhancement function that adopts logarithm transform could stretch illumination component, so whole visual appearance is improved. Then reflection component is adjusted by nonlinear function that involves discriminating ability of image gray level for human eye, consequently local contrast of image is enhanced. Experiments show that our method does not cause color distortion for RGB and some chroma-luminant color spaces, visual appearance is well, and operation cost is lower than that of Multi-Scale Retinex (MSR).