Study And Design Of Infrared Image Pre-processing System Based On FPGA

With the development of infrared detection technology and very large scale integration, real-time infrared imaging system has been applied more and more.How will the infrared image be processed real-timely aiming at the characteristics of infrared image, and how does get the infrared image that can reflect the detection scene truly and will be appropriate for observation and analysis? These are study hot points of infrared imaging technology at present.It is significant that infrared image is pre-processed immediately after collected and simplifying the backward burdensome processing task of digital signal processor.The main works of this paper are provided:(1)The principle of infrared imaging, the forming procedure of infrared, the characteristics of infrared image and the difference between infrared image and visible light image are illustrated.(2)The enhanced arithmetic of image in frequency field and the grayness transform principal of image are introduced in detail in this paper.(3)Some arithmetic which is appropriate for the pre-processing of infrared image is chosen to structure hardware by analyzing and comparing all of arithmetic in the time field and the manner of time field processing and frequency field processing. Then the best methods of smooth and sharpness are decided according to difficulty degree of structuring hardware and impropriation rate of hardware resource and the eventual processing effect to image.(4)Aiming at the characteristics of Filed Programmable Gate Array (FPGA), the modulization design is adopted for structuring parallel operation expediently. It incarnates fully the requirement of real-time processing.(5)The statistics histogram of infrared image is carried out through the analysis to hardware structure of grayness transform of infrared image.(6)The I~2C Bus Standard is elucidated. And the controller which configures to SAA7115 video processing chip by PC Bus is designed to use for collecting analog infrared image and being quantitated digital . image signal. Because Synchronous Direct Random Access Memory (SDRAM) to store data is adopted, it is necessary that SDRAM controller is designed for storing quantitated data into SDRAM according to the manner of writing data and reading data.(7)The hardware structure method of image processing in frequency field is explained in detail, especially the difference of hardware structure of Discrete Fourier Transform (DFT) between FPGA and Digital Signal Processor (DSP) is explained. Eventually the Phase Lock Loop Core is adopted for structuring the time-sequence portion of the system according to the requirement of time-sequence structuring and time-sequence request of the whole system. And the system is optimized for promoting the operation speed and decrease impropriation rate of hardware resource.