基于形态小波变换的低对比度图像增强算法

针对传统的图像对比度增强方法所存在的一些问题,提出了一种基于形态小波变换的图像增强算法.首先,将低对比度图像采用基于提升格式的形态Haar小波进行小波变换,得到小波系数,该小波变换实现结构简单,计算量低,并且有利于图像重要的几何信息在低分辨率空间中的保留.然后,对低频子带小波系数,采用直方图双向均衡方法进行调整,对高频子带小波系数进行基于软阈值滤波的细节系数增强,将调整后的小波系数反变换到空域上,得到增强后的结果.最后,给出几种增强算法实验结果的比较和分析,表明该算法对低对比度图片的增强是非常有效的,可以有效地增强图像的细节信息,保持图像的边缘特征,改善图像的视觉效果.

Algorithm of Low Contrast Image Enhancement on Morphological Wavelet Transform

To improve conventional methods for contrast enhancement, this paper presents an image enhancement algorithm based on morphological wavelet transform.The morphological Haar wavelet based on lifting-structure was chosen to convert the low contrast image and obtain wavelet coefficients. The morphological wavelet transform is simple and has lower computational complexity.It is fit for protecting the important geometry information in low-frequency space.The low-frequency wavelet coefficients are enhanced by the histogram double equalization method. For the high-frequency wavelet coefficients,the soft threshold method was utilized to enhance the details of the image. Finally, the inverse wavelet transform is applied to map the result into space domain. Experimental results of the proposed approach and other conventional methods are compared and analyzed to demonstrate that the proposed approach is very effective in enhancing the details and protecting the edge information of the low contrast image with good visual effect.