天问一号高分相机火表复杂照度下自动调光成像电路设计

Design of auto-exposure imaging circuit under complex illuminance of Mars in Tianwen-1 high-resolution camera

航天相机的成像质量是获取遥感数据的关键,航天相机设计中调光是影响相机的成像质量的重要参数,自动调光是预先获取目标场景的信息,根据信息确定调光参数,避免过度曝光或曝光不足带来的图像信息损失。我国首次火星探测任务天问一号高分相机,针对火表复杂照度,为获取高质量图像数据,提出了基于TDI CCD推扫成像与CMOS凝视成像自动调光成像电路设计,并提出了基于FPGA的自动调光算法。对天问一号高分相机进行自动调光试验,试验结果表明:自动调光后图像的动态传函MTF提升0.013,外场试验中,对实际景物进行自动调光前后对比拍摄,结果表明自动调光成像效果良好,具备较好的场景适应能力,满足火表复杂照度下自动调光成像需求。

The imaging quality of a space-borne camera is key to accurately obtain remote-sensing data.Exposure is an important parameter in the design of a space-borne camera,which affects the image quality of the camera. Auto-exposure obtains information from the target scene in advance and uses it as the basis for determining the exposure,which can avoid the loss of image information by overexposure or underexposure. In order to obtain high-quality image data from the high-resolution camera in Tianwen-1 under the complex illuminance of Mars,an auto-exposure imaging circuit,based on TDI CCD push-broom and CMOS staring imaging,and an FPGA-based auto-exposure algorithm is proposed. The auto-exposure experimental results from the high-resolution camera in Tianwen-1 show that the dynamic transfer function MTF of the image after auto-exposure is increased by 0. 013. In an outdoor test,a comparison of the actual scene before and after the auto-exposure shows that the effect of auto-exposure is good,with better scene adaptation. The proposed circuit has the ability to meet the requirements of auto-exposure imaging under the complex illumination of Mars.