图像对比度增强的非线性变换法

Non-linear transform algorithm for image contrast enhancement

对原始图像用所提出的判据判断图像的对比度类型,针对不同类型直接确定灰度变换参数,实现图像全局对比度增强。再对图像进行离散平稳小波变换,利用所提出的非线性增强方法分别对各个分解层的高频子带进行细节增强。实验表明,提出的方法在有效提高图像整体对比度的同时,又能突出图像中目标的细节部分信息。

Contrast type of original image is determined by a new criterion. Gray transform parameters are directly obtained by the new criterion. Global enhancement is implemented to the original image. After making discrete stationary wavelet transform to the enhanced image, details enhancement is done by certain nonlinear operator in the high frequency sub-bands of each decomposition level respectively. Experimental results show that the new algorithm can enhance the global contrast of image effectively; meanwhile it also emphasizes the detail information of the target in the image well.