中值滤波是一种基于空域排序统计的图像降噪方法,可在滤除噪声的同时有效保护图像的细节信息。传统中值滤波一般采用冒泡排序法来对方形窗口内的像素灰度值进行排序操作,像素之间的比较次数多,处理时间长,不利于实时图像处理。基于图像并行处理的思想,提出了一种基于横向拓展窗口的快速中值滤波算法。算法将传统的方形窗口进行横向拓展,从而改变滤波窗口漫游的滑动步长,同时可以有效利用算法执行过程中的比较信息,达到提高整幅图像处理速度的目的。实验结果表明,算法能够满足图像降噪高精度、高实时性要求。所提出的算法通过牺牲芯片面积来换取处理速度,适宜于在现场可编程门阵列等硬件上实现。

Median filtering is a spatial-order-statistics based image denoising method,which can preserve image details well while eliminating noise. In traditional median filters,the pixels in a square window is often sorted by bubble sorting,which demands large comparison times and long processing time,and is unfit for real-time image processing. Based on image parallel processing technology,a fast median filtering algorithm based on extended window is presented. In the proposed algorithm,the traditional square window is extended transversely,so the sliding step of window roaming can be increased by pixels to achieve much higher processing speed for the whole image,while the comparison results within the process of executing the algorithm are effectively used. The result shows that the algorithm can achieve high precision and real-time ability in image denoising. The algorithm improves the image processing speed by the cost of more area of hardware chip,and it is suitable for implementation on hardware such as field programmable gate array.