关键词: 椒盐噪声, 三维块匹配（BM3D）, 相似块, 图像去噪

Abstract: When dealing with the high-contrast images contaminated by salt-and-pepper noise, the traditional Block-Matching and 3D filtering（BM3D） can not effectively preserve the edges and texture details of the image, it will appear edge-ringing effect in the denoised image edges. In order to improve the shortcomings of traditional BM3D algorithm when dealing with salt and pepper noise, an improved denoising algorithm of BM3D is proposed, which uses the edge direction instead of the horizontal direction to search for similar blocks. The experimental results show that the number of similar blocks obtained by the improved BM3D algorithm is three times higher than that of the traditional BM3D algorithm, and the Peak Signal-to-Noise Ratio（PSNR） is further improved, and the edge of the image is effectively preserved while salt and pepper noise is removed.

Key words: salt and pepper noise, Block-Matching and 3D filtering（BM3D）, similar block, image denoising