利用对数变换进行图像变换
公式：x1=c*log(double(x)+1)(1.Image Enhancement Using Intensity Transformations
　 The focus of this project is to experiment with intensity transformations to enhance an image. Download Fig. 3.8(a) and enhance it using
　 (a) The log transformation of Eq. (3.2-2).
　 (b) A power-law transformation of the form shown in Eq. (3.2-3).
　 In (a) the only free parameter is c, but in (b) there are two parameters, c and r for which values have to be selected. As in most enhancement tasks, experimentation is a must. The objective of this project is to obtain the best visual enhancement possible with the methods in (a) and (b). Once (according to your judgment) you have the best visual result for each transformation, explain the reasons for the major differences between them.)