Exponential contrast maximization of intensity images

In this paper a novel approach is proposed to approximate the exponential correction factor of grayscale images which maximizes the contrast of the image in the class of exponential intensity mapping functions. The error of approximation is less than 10% compared to the optimal exponent determined by the iterative bisection method. Besides the method maximizes the contrast in the class of exponential functions, it can be used to restore under- and over-exposed images. In the tests well exposed images were exponentially distorted and the result of contrast enhancement using the proposed method and histogram equalization are compared. Although the contrast provided by the proposed method is smaller, the resulting images are smoother than in the case of histogram equalization, furthermore the results of the exponential contrast maximization have higher correlation with the original images than histogram equalized distorted images.