Circuit Design For Infrared And Visible Image Acquisition System With Single Channel

As the development of optical imaging technology, visible imaging and infrared imaging has been widely used. Visible images rich in color and texture information of the target, which is suitable for human visual habits, and target can be easily recognized. Infrared Images reflects the information of target temperature distribution, but not suitable for human visual habits. As deepening of the research, it is needed to recognize the target directly and obtain its temperature distribution at the same time. Now, most of visible and infrared image fusion systems have two video input channels, namely, the two cameras take images of the same target from the different views, leading to that only when the target is static, the registration can be accurate, which limits its scope of application.This paper designed a system of long-wave infrared and visible images capturing and fusion for power line inspection, in which, the circuit design is analyzed in detail. FPGA is the main control device of the hardware circuit, controlling peripheral devices. Firstly, using FPGA to drive the visible CMOS image sensor, constructs a circuit module of visible camera, which resolution is 1280×1024 and frame rate is 25 fps. This module provides visible image source for the image fusion system. In addition, based on “medial gray” theory, we designed an automatic exposure algorithm for this camera. With automatic exposure parameter adaptively adjusted and fixed step adjusted, the algorithm can achieve the exposure parameters quickly and accurately.Secondly, in order to meet the requirements of time correlation for image fusion, we capture a frame of visible image and a frame of infrared image at the same time by using output timing character of the visible image sensor and infrared image sensor under the control of FPGA. Then, we developed a method to transmit two videos via HDMI at the same time, namely, merging a visible image and the corresponding infrared image into a new image, in other words, it is to merge a visible light video and an infrared light video into a new video of 1080P@25fps, which outputs through HDMI interface under the control of FPGA.Finally, we verified that every circuit module is in working state by testing the important signals in hardware circuit. After the test with image fusion software on host computer, we got that the image fusion system works under a good result of image fusion, and achieves the desired design goals of observing the temperature distribution and texture information at the same time.