Design And Implementation Of A High Dynamic Infrared Thermal Imaging System

With the continuous development of infrared focal plane manufacturing technology,the resolution of infrared thermal imaging sensor is continuously improved,the infrared image data acquired is wider and wider,and the dynamic range is also higher.However,because the gray range of the image displayed by the display device is 0-255,it is impossible to display all the details of the high dynamic range data through the display device.To solve this problem,we study how to compress the high dynamic data of infrared thermal imaging on display and enhance the details.On the other hand,in scenarios where power consumption,size requirements are stringent,and real-time requirements are high,for the application requirements of infrared thermal imaging equipment.The hardware implementation of the high dynamic infrared image compression and detail enhancement algorithm based on FPGA is proposed in this paper.It has important practical significance and application value for the development and application of infrared thermal imaging technology.In order to realize the compression and detail enhancement of high dynamic infrared image,on the basis of analyzing the characteristics of infrared images and the classic infrared image dynamic range compression and detail enhancement algorithms,a dynamic range compression and detail enhancement algorithm based on bilateral filter layering is adopted.First,bilateral filtering and Gaussian filtering are used to layer the image.Then,the histogram projection based on gray-scale redundancy is used to compress the base layer image,and the gain coefficient is used to enhance the detail layer image and suppress the noise.Finally,the base layer image and details layer images are superimposed to obtain 8-bit processed images.In order to meet the requirements of low power consumption,miniaturization and real-time performance of the system,a high dynamic infrared thermal imaging system based on FPGA is designed by analyzing the principle of infrared thermal imaging technology and the structure of infrared thermal imaging system.The system mainly includes four parts: image acquisition,image processing,image transmission and host computer interface design.In this design,the image acquisition part uses FPGA to perform logic and timing control on the video output of the infrared thermal imaging movement.Due to the large amount of original infrared image data,DDR2 SDRAM chip is selected as the storage device.In order to increase the image processing speed,image processing part is completed based on FPGA,and the hardware implementation method of bilateral filtering and histogram projection algorithm is given.In order to realize the fast transmission of the image,the image transmission part adopts Ethernet and selects UDP network protocol for data transmission.In view of the packet loss problem of UDP protocol,the method of setting a flag for each data frame is adopted.In order to solve the problem of receiving and displaying infrared images,the upper computer interface design is completed by using Python language.In order to test the performance of the system,the correctness of the network transmission module is verified by analyzing the Ethernet frame data captured by Wireshark.And the real-time performance of the network transmission is verified by testing the Ethernet transmission speed.The infrared image processed by the system is displayed by the upper computer interface.The research results of this paper provide a reference for realizing the low power consumption,miniaturization and real-time application of the infrared thermal imager.