Study Of Pixel-level Light Adjusting Technology Based On DMD

It is required that the dynamic range of imaging equipment system reaches above 120 d B in the observation application of high dynamic range scenes, such as deep space exploration, the observation of solar activity, the launching of rocket, missile and spacecraft. However the imaging dynamic range of traditional CCD or CMOS image sensor is not sufficient enough to satisfy the requirement of scientific observation in a high dynamic range scene at present and the technology of extended tools of existing imaging systems cannot meet the requirement of real time imaging targets with high intensity as well.This paper brings forward a method of employing a digital micromirror device(DMD) as a spatial optical modulator so that the light of image plane obtained by traditional imaging equipment would attenuate by pixel-level. After attenuation targets with high light intensity and low light intensity in the same scene can be detected simultaneously and displayed in the same image. By such means, the detectable dynamic range of traditional imaging system is enlarged.A DMD driver control program applied in high dynamic range scene is designed based on a DMD control suite, which improves the modulation ability of DMD and extends the dynamic range of traditional imaging equipment to above 60 d B while ensuring the imaging frame to be above 10 fps. In addition, by embedding correlated quadruple sampling algorithm and high dynamic range data synthesis algorithm on the FPGA chip inside of camera, a specialized s CMOS camera with high dynamic range is developed and acted as the imaging equipment, which is enabled to produce high resolution, high definition and high dynamic range image data under the global shutter mode. It is measured that the dynamic range reaches 78 d B. The s CMOS camera and DMD described above can be triggered simultaneously by the accuracy of 1 ?s and the dynamic range of the whole imaging system can reach above 120 d B.In the process of developing the electrical and optical platform, the phase properties of Moire fringe are employed to guide the accurate matches between unite of micromirror and pixel, and to analyse and adjust the distortion of special optical system. It is verified that the mapping accuracy between unite of micromirror and pixel reached pixel-level. Provided with this platform, a precise light adjusting model at pixel-level is established by analyzing the effect of the swing of micromirror, the linearity of micromirror modulation and s CMOS response, and the delay of starting time of exposure and preliminary results of imaging in high dynamic range scene are obtained.We establish the precise model of the pixel-level light adjusting.The dynamic range of experimental verification system is more than 126 d B by developing a light adjusting algorithm that recovers the static and the original scene which integrates the light adjusting algorithm at pixel-level in high dynamic range with properties of human visual system. Moreover, a light adjusting algorithm with high speed is proposed based on threshold segmentation, which can observe high dynamic range scene in real time and compression operator for high dynamic range imaging combined with global operator and local operator is proposed, which improves the display of image data obtained from high dynamic range scene.