研究和设计了一种新型自适应双向扩散过程,对无源毫米波图像进行降噪和增强处理.根据图像的局部特征进行自适应扩散处理，在图像的同质区域进行各向同性扩散降低噪声，在图像的边缘处沿着图像边缘的切向方向进行正向扩散降低噪声，沿着图像边缘的法向方向进行反向扩散锐化边缘.通过对仿真图像和实测的91.5 GHz无源毫米波图像的实验表明，该算法对无源毫米波图像有显著的降噪与增强效果.

A new adaptive bidirectional diffusion process that denoises and enhances passive millimeter wave images is designed and analyzed, which can diffuse adaptively according to the local characteristics of the image. In the flat areas of the image, it executes an isotropic diffusion to denoise. On the edges of the image, it executes a forward diffusion along the tangent direction to the isophote lines to denoise, and a backward diffusion along the normal directions to sharpen edges. Experimental results, completed with simulated image as well as actual passive millimeter-wave image at 91.5 GHz, demonstrated that it can substantially denoise and enhance passive millimeter wave images.