对比敏感度下的图像对比度评价

Image Contrast Assessment under Contrast Sensitivity

目的为解决局部带限对比度存在的问题,提出一种对比敏感度下的图像对比度评价方法.方法对低通滤波后的图像进行快速小波分解,然后对各级小波系数进行处理分别得到各级带通滤波图像及其相应低通滤波图像,求出Peli局部带限对比度,并根据熵的定义计算带限对比度熵,最后利用CSF系数对所得结果进行加权求平均得到图像的对比度熵.结果可以在调节光圈大小得到的序列图像中准确找出对比度最好的一幅,评价结果更加符合人眼的视觉特性.结论解决了局部带限对比度对曝光不足导致的细节丢失图像不能给出正确评价的问题,并且可以应用于图像增强算法中,对增强效果进行准确可靠的评价.

In order to overcome the problems of local band-limited contrast, a novel contrast sensitivity image contrast assessment method based on the property of CSF was proposed. Firstly, the image by low-pass filter is performed fast wavelet decomposition;secondly, all levels of band-pass filtered image and its correspond- ing low-pass filtered image are obtained by processing wavelet coefficients; thirdly, local band-limited contrast is calculated, and the local band-limited contrast entropy is calculated according to the definition of en- tropy;finally, the contrast entropy of image is obtained by averaging the local band-limited contrast entropy weighed using CSF coefficient. The experiment results show that the best contrast image can be accurately i- dentified in the sequence images obtained by adjusting the aperture size, assessment results accord with hu- man visual characteristics. It solves the problem of the local band-limited contrast of not giving the correct e- valuation to underexposed images, and can be applied to image enhancement algorithms and give accurate and reliable assessment.