THz激光主动图像预处理方法研究

鉴于THz激光主动成像以其较低的光子能量和较高的穿透能力在危险品检测、医疗和食品检验等领域有着广泛的应用前景，将对比度拉伸变换、中值滤波和均值滤波常规图像预处理方法引入到THz激光主动图像处理中，对五元人民币纸币的水印THz面阵图像进行了预处理。处理结果表明，对原始图像进行对比度拉伸变换可以较大地提高图像对比度，在此基础上进行的中值滤波和均值滤波可进一步提高图像的辨识能力，中值滤波可以保护目标边缘细节并使图像平滑。在对比中发现，当窗口大小为9×9像元时滤波后的视觉效果最佳。

Study on pre-processing of THz laser active image

THz laser active imaging is a kind of new imaging system. It has great potentials in hazardous material detection, medical care and food inspection because of its low photon energy (about 4.1meV per THz) and high penetration capability. In this paper, the contrast stretching transformation, median filtering and mean filtering are applied to pre-process the THz array image of a 5RMB watermark. The processing results show that these imaging processing methods could be introduced to the preprocessing of THz laser active image and satisfactory results are obtained.