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红外光斑中心检测在红外自动验光仪、红外测距仪等光学测量和检测仪器中是一项关键技术,检测算法的精度、速度直接影响光学测量的精度及速度。目前的检测处理系统多是基于PC机的,存在着实时性、稳定性问题。在总结各种检测算法的基础上,基于重心法使用FPGA实现了低信噪比红外光斑中心的实时检测。在实验电路中,先使用视频解码芯片SAA7113将模拟CCD视频信号转化为CCIR656格式数字信号;再在FPGA内部使用流水线结构进行直方图计算,计算阈值,二值化图像,五次二值图像收缩,五次二值图像膨胀处理以去除噪声,然后计算重心坐标。实验电路对红外自动验光仪中产生的视网膜反射红外光斑PAL制式视频图像信号能在1/25 s完成一幅图像的检测。而普通PC完成同一过程需要1 s左右。文章介绍了基于FPGA实现方案。
Infrared spot center detection in the infrared automatic refractor, infrared rangefinder and other optical measurement and detection equipment is a key technology, the accuracy of the detection algorithm, the speed of a direct impact on optical measurement accuracy and speed. The current detection and processing system is mostly based on PC, there is real-time, stability issues. Based on the summarization of various detection algorithms, real-time detection of low signal-to-noise ratio infrared spot center is realized based on the method of center of gravity. In the experimental circuit, the first use of video decoder chip SAA7113 analog CCD video signal into CCIR656 format digital signal; and then use the pipeline structure within the FPGA histogram calculation, calculation threshold, binary image, five binary image contraction, Five binary image bloat processes to remove noise and then calculate the barycentric coordinates. Experimental circuit on the infrared refractor produced in the retina reflex infrared spot PAL standard video image signal in 1/25 s to complete an image detection. The ordinary PC to complete the same process needs about 1 s. The article introduced based on FPGA implementation plan.