Hanmandlu Madasu, Jha Devendra
Indian Institute of Technology, Delhi, New Delhi, India.
IEEE Trans Image Process. 2006 Oct;15(10):2956-66. doi: 10.1109/tip.2006.877499.
A Gaussian membership function is proposed to fuzzify the image information in spatial domain. We introduce a global contrast intensification operator (GINT), which contains three parameters, viz., intensification parameter t, fuzzifier fh, and the crossover point mu(c), for enhancement of color images. We define fuzzy contrast-based quality factor Qf and entropy-based quality factor Qe and the corresponding visual factors for the desired appearance of images. By minimizing the fuzzy entropy of the image information with respect to these quality factors, the parameters t, fh, and mu(c) are calculated globally. By using the proposed technique, a visible improvement in the image quality is observed for under exposed images, as the entropy of the output image is decreased. The terminating criterion is decided by both the visual and quality factors. For over exposed and under plus over exposed images, the proposed fuzzification function needs to be modified by taking maximum intensity as the fourth parameter. The type of the images is indicated by the visual factor which is less than 1 for under exposed images and more than 1 for over exposed images.
提出了一种高斯隶属函数，用于对空间域中的图像信息进行模糊化处理。我们引入了一个全局对比度增强算子（GINT），它包含三个参数，即增强参数t、模糊化器fh和交叉点mu(c)，用于彩色图像的增强。我们定义了基于模糊对比度的质量因子Qf和基于熵的质量因子Qe以及图像期望外观的相应视觉因子。通过相对于这些质量因子最小化图像信息的模糊熵，全局计算参数t、fh和mu(c)。通过使用所提出的技术，对于曝光不足的图像，观察到图像质量有明显改善，因为输出图像的熵降低了。终止准则由视觉和质量因子共同决定。对于曝光过度以及曝光不足加曝光过度的图像，需要通过将最大强度作为第四个参数来修改所提出的模糊化函数。图像类型由视觉因子指示，对于曝光不足的图像，视觉因子小于1，对于曝光过度的图像，视觉因子大于1。
