关键词: 虚拟内窥镜系统, 医学图像去噪, 自适应算法, 中值滤波, 脉冲噪声

Abstract: An adaptive median filter that can remove impulse noise in medical images is implemented, and it is compared with traditional median filter and averaging filter by two objective evaluation criteria, root-mean-square error and destroyness degree of noise to original image. The pixel at the center of filtering window is detected to determine whether it is an impulse noise based on given condition. Median filter with adaptive window is applied to eliminate the noise. The algorithm overcomes the shortcoming of median filter that replaces the value of each pixel by the median of the gray levels in the neighborhood of that pixel, and reduces unnecessary loss of image detail. Simulation results based on MATLAB show that, for larger impulse noise density, it not only eliminates noise effectively, but also preserves the edges and detail information of the objects. The algorithm has been used in the virtual endoscope system, and the filtering performance is very satisfactory.

Key words: virtual endoscope system, medical image filtering, adaptive algorithm, median filter, impulse noise