Research And Implementation Of IR Night Vision Image Enhancement System Based On FPGA

The infrared night vision imaging technology can monitor all kinds of personnel,vehicles and other targets without exposing the supervisor himself in the night and is widely used in the field of safety guard in public security system.The basic principle of such technology is using the infrared radiation signal to trigger the infrared detector and form a recognizable image by photoelectric conversion and then show it on the screen.In this paper,we designed the module on the chip through FPGA image processing technology.Combined with the infrared image acquisition,storage,processing,display technology and an improved IIR digital filter,we designed an infrared image enhancement system by making use of the chip's parallel high-speed characteristics,thus realizing the covert monitoring and real time display of the targets at night.In this paper,the infrared night vision image enhancement system was designed based on FPGA,Verilog HDL development technology and the infrared image processing technology.The main tasks are described as follows:Firstly,in the direction of infrared imaging technology,we had a systematical expounding of the development and principle of infrared imaging,and compared the difference of infrared image with visible light image.On the basis of studying the theory of infrared image enhancement,we respectively had a simulation research and comparison of two-point temperature calibration method with non-uniform correction and LMS algorithm,as well as the histogram equalization algorithm and the adaptive piecewise linear algorithm.In the paper,the structure,working principle and development platform of FPGA were studied,and the characteristics of FPGA chip of Cyclone IV family were analyzed.We chose the EP4CE22F17C8 N chip of Cyclone IV family as the core of hardware,the ADV7180 chip for image decoding and A/D conversion,two high-speed DDR2 SDRAM for image storage,and a 7-inch AT070TN83 V.1 LCD screen for real-time display of infrared images.Based on the above devices,the hardware platform of infrared night vision image processing system was built.Secondly,we had a top-level design for the software part of the infrared night vision system.In the design process,based on the analysis of ITU-R BT.656 video format,the infrared image acquisition and decoding module were designed and implemented first.Secondly,the DDR2 SDRAM control module was designed and configured,and was then simulated.Thirdly,the LCD screen driver module was designed by studying the sequenceconthol of LCD,which finally realized the collection,storage and real-time display of infrared image.Finally,the infrared image format conversion algorithm was realized based on FPGA.Additionally,according to the characteristics of infrared image that is susceptible to noise pollution,the IIR digital filter based on FPGA was designed and improved.At the same time,the whole system was jointly debugged,and we realized the real-time enhancement processing of infrared image and carried out ModelSim simulation by utilizing the characteristics of the filter's fast convergence and FPGA parallel processing,which has achieved better denoising effect.Through the imaging experiments of different targets,we prove that the system has reached the design requirements.