An Unsharp Masking Technique for Image Enhancement with Noise S uppression
XIE Mingguo,HE Jianguang,XU Zhongyou,ZHANG Yanchen
(Xiamen University,Xiamen,361005,China)
Abstract:A new method for unsharp masking technique for imag e enhancement is presented in order to reduce noise sensitivity of traditional u nsharp masking technique. Denoising operation is performed in smooth areas of images. The sharpening depth varies automatically in different contrast areas of images based on human visual properties. Experimental results show a much impr oved enhancement and noise suppressing
Keywords:image enhancement; unsharp masking; noise suppressi on;alorithm
为了克服线性反锐化掩模技术的缺点,尤其是对噪声的敏感性,人们提出了各种各样的方法。这些方法大部分是用非线性滤波器代替线性高通滤波器,对减小噪声和增强细节进行折中考虑。SK Mitra提出了基于Teager算法的非线性算子[2],这种非线性算子可近似为局部均值权重高通滤波器。根据Weber定律,人眼对图像黑色区域的细节更敏感,因此这种算子能减小噪声。G.Ramponi提出了立方反锐化掩模技术[3],这种技术的实质是用一个对边缘敏感的平方滤波器算子乘以拉普拉斯算子,仅增强局部亮度变化区域的图像细节,相对较小噪声。Y H Lee提出了基于序列统计拉普拉斯算法的算子[4],这个算子的输出和局部均值与局部中值之差成比例,他能有效地去除高斯白噪声。A Polesel提出了自适应反锐化掩模技术[5],这种技术采用自适应滤波器对图像的细节增强程度大一些,而对图像的平坦区域几乎不增强,因而能减小平坦区域的噪声。
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