由于数字图像在生成与传输过程中容易受到脉冲噪声的污染,往往造成后续处理难以为继.为了改善图像质量,需要对图像进行去噪处理.针对传统中值滤波及其它非线性滤波方法在去除图像脉冲噪声时存在的不足,本文提出了一种改进的去噪方法:在滤波之前进行一次脉冲噪声检测,确定受到噪声污染的像素点,并进行记录标识；然后根据检测结果进行改进的中值滤波:只对判断为噪声点的像素进行处理,不仅考虑了标准中值,也分情况利用了中值的前一个值和中值的后一个值的信息.实验表明,改进方法不仅在滤除脉冲噪声方面相比其他非线性滤波有很大改进,而且它可以更好地保护图像的细节特性,对图像的后续处理有很好的价值.%Digital images are often corrupted by impulse noise during the acquisition or transmission. In order to improve the image quality, it is necessary to remove impulse noise. Aiming at the shortcoming of traditional median filter and the other median-based nonlinear filters in de-noising image, an improved de-noising algorithm is proposed in this paper. Impulse noise checking is made before filtering so as to confirm the pixels polluted by noise, which are recorded and marked. Then, according to the nose detection results, an improved median filtering is adopted to remove the impulse noise. This proposed algorithm only handle the pixels polluted by noise. It not only make use of the standard median, but also use the last value before the standard median and the first value after the standard median. Experiments proves that the improved method can not only provide better performance of suppressing impulse noise than other median-based nonlinear filters, but also preserve more detail features.
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