高光谱成像的纸币真伪鉴别研究

人民币是中华人民共和国的法定货币，人民币的真假直接关系到我国社会的和谐与稳定。百元钞票作为我国最大面额钞票，其真假的鉴定显得更为重要。以2005版的百元钞票为例，利用可见/近红外高光谱成像仪获取一张真钞与两张假钞正、背面高光谱影像数据，然后分别在百元钞票的正、背面选取4个特征点，以分析百元真假钞票在正、背面的光谱反射率差异。从真假钞正面四个特征位置的光谱反射率曲线可知，不同特征点处，真钞与假钞之间的有些图案的光谱反射率差异较大，有些图案的光谱反射率则差异并不显著。而不同批次的假钞，其不同位置的光谱反射率也存在较大的差异。对于真假钞背面的分析可知，不同特征点，在不同的波段，真钞与假钞以及假钞之间的光谱反射率同样有一定的差异。根据真钞与假钞正、背面8个特征点的光谱反射率曲线变化特征，选取500, 660和870 nm三个波长的灰度图，观察到真钞与假钞在不同特征点的灰度图均表现出明显的差异。真钞在500 nm处的图像轮廓清晰，在660和870 nm两个波长，无论是正面或背面，真钞均有多处特征位置有异于假钞，因此可用660或870 nm区别百元真假钞。为了突出真钞与假钞之间的图像差异，利用基于...

Identification of True and Counterfeit Banknotes Based on Hyperspectral Imaging

RMB is the legal currency of the people’s Republic of China. The authenticity of RMB is directly related to the harmony and stability of the society. As the most significant denomination bill in China, identifying the authenticity of 100 yuan RMB is more critical. In the paper, we use the visible/near-infrared hyperspectral imager to obtain the hyperspectral image data of an actual bill and two fake bills. Then select four feature points on the front and back of the bill to analyze the spectral differences between the front and back of the bill.From the spectral reflectance curves of the four characteristic positions on the front of the authentic and counterfeit banknote. It can be seen that the spectral reflectance of some patterns between the real and the counterfeit banknote varies greatly at different characteristic points, while that of some patterns is not significant. Moveover, for different batches of counterfeit banknotes, the spectral reflectance at different locations also has large differences. The analysis of the back of real and counterfeit banknotes shows that with different feature points, the spectral reflectivity between the real and the counterfeit banknote is also different in different bands. According to spectral reflectance curves of the 8 characteristic points on the front and back of the genuine and the counterfeit banknote, the grayscale images of the wavelengths at 500, 660 and 870 nm were selected. It was observed that the grayscale images of real and counterfeit banknotes showed obvious differences at different feature points.The image contour of the real banknote at 500 nm is clear. In 660 and 870 nm, no matter on the front or back, the real banknote has several characteristic positions different from the counterfeit banknotes. Therefore, it can be used to distinguish the real 100-yuan banknote at 660 or 870 nm. In order to highlight the difference between real banknotes and counterfeit banknotes, the gray-scale image of real and counterfeit banknotes of 100 yuan is obtained by band calculation. As can be seen from the figure, real banknotes are different from counterfeit banknotes in many places on the front and back sides. From the grayscale image of the first 12 principal components on the front of genuine and counterfeit banknote, it can be seen that there exist significant differences in each principal component no matter from the front or the back.According to the texture feature map on the front and back of the real and fake banknotes, it can be seen that the texture characteristics of the real banknotes are significantly different from the fake banknotes. The results show that the spectral reflectance of 100 yuan real banknotes is significantly different from that of different versions of counterfeit banknotes in the visible/near-infrared spectral range, and the differences between the front and back positions of 100 yuan real banknotes can be found by the near-infrared characteristic band, spectral operation, principal component analysis and texture characteristics. Therefore, visible/near-infrared hyperspectral imaging technology can be used to identify 100 yuan real and fake banknotes and provide the possibility and theoretical support for the traceability of counterfeit banknotes. The technology has practical significance in the actual practice of public security.