License plate segmentation is a key technology in the process of license plate location and recognition. How to realize automatic segmentation of license plate image under complex illumination conditions has been a hot issue in intelligent transportation system (ITS). This paper deals with license plate image segmentation under a variety of lighting conditions. Based on the adaptive segmentation of license plate images by the Pulse Coupled Neural Network (PCNN), the relationship between the license plate image contrast and the PCNN iteration entropy is analyzed. An adaptive segmentation algorithm for license plate image using Deep Neural Network (DNN) to select the optimal result is proposed, and the selected segmentation image is filtered by the connected domain, which lays a foundation for subsequent license plate location, character segmentation and recognition. Simulation experiments show that the proposed algorithm performs better license plate segmentation and optimal selection for license plate images under various lighting conditions.
In recent years, metal nanostructure has had rapid development and application in novel optical sensor, filter , optical transparent electrode and other fields, so the study for the design of metal composite nanostructures and the design’s optical characteristics not only has laid the foundation for extraordinary optical transmission (EOT), but also had important significance in the development of optical devices mentioned above all. This paper uses the method of finite difference time domain (FDTD) to calculate the three-dimensional the double square ring metal nanocomposite structure models. We studied a series of factors, such as the parameters of the metal silver film, the groove width and the incident plane wavelength, and so on. As the result of our study, we found that the light transmission intensity of this composite structure is much higher than separated large or small hole array structures. It’s because the resonant excitation of the composite surface plasmon polaritons (SPPs) and the strong coupling are more remarkable in the double square ring structure. Through the study of kinds of composite structures, we discovered that some small holes to be cut in the metal film structure will be more conducive to the light transmission intensity. It is a great potential value in the research and development of optical devices.
The non-resonantly enhanced optical transmission phenomenon of sub-wavelength metallic slits on a thin film is significant for broadband light integrated devices. In order to improve the EOT characteristics of sub-wavelength metallic slits further more, in this paper, wedge-shape metallic slits array embedded with rectangular cavities structure is proposed and its transmission properties are investigated using the finite element method. The results show that wedgeshape metallic slits array can achieve higher transmission compared with straight slits array embedded with rectangular cavities and the light is strongly localized and enhanced at the slit exits. We describe the phenomenon with a transmission line model. The width of entrance of the slit influences the transmission property: the transmittance can be 94%, after optimizing the structure parameters, with the widths 150nm and 30nm at the entrance and exit of the slit, respectively. The thickness of metal film influences the transmission peak position and transmission rate: when the increase of the thickness of the metal film, the transmittance increases and the transmission peak is red-shift, however, the law of long wavelength range is opposite. In addition, the effects of structural period of wedge-shaped slits embedded with rectangular cavities structure on the transmission property are also studied. These results would be helpful for optical signal transmission and the design of near field optical conductor devices with higher transmission capability.