消除光学渐晕的FPGA实时校正系统

FPGA Real-time Correction System for Eliminating Optical Vignetting

摘要:

光学渐晕效应存在于大部分光学成像系统,严重影响成像质量。如何有效改善光学渐晕效应是航天光学遥感器设计的要点。采用辐射定标方法量化成像系统中光学渐晕效应的影响,并获得校正系数。采用多项式拟合方法对校正系数进行优化,拟合后校正系统减少约3个数量级,大大降低了对嵌入式系统存储资源的需求。通过多项式拟合方法有效减少了校正系数,对光学渐晕效应改善效果良好,校正前相机的非均匀性误差为13.2%,校正后非均匀性误差降至3.8%,满足一般成像系统对响应非均匀性的要求。该方法校正系数少,适合在基于FPGA处理器中实现,实时性强,资源占用少,具有工程实用价值。

Abstract:

The optical vignetting effect exists in most optical imaging systems, which seriously affects the imaging quality. How to effectively improve the optical vignetting effect is the key point in the design of aerospace optical remote sensors. A radiometric calibration method was used to quantify the influence of the optical vignetting effect in the imaging system and to obtain the correction coefficients. The correction coefficients were optimized by polynomial fitting method, and the correction system was reduced by about three orders of magnitude after fitting, which greatly reduced the demand for storage resources of the embedded system. The polynomial fitting method effectively reduced the correction coefficients and improved the optical vignetting effect. The non-niformity error of the camera before correction is 13.2%, and after correction, the non-uniformity error is reduced to 3.8%, which meets the requirements of general imaging systems for response non-uniformity. The method is suitable for implementation in FPGA-based processors with fewer correction coefficients, high real-time performance and low resource consumption, and has practical engineering value.