线阵CCD平场校正及FPGA实现的研究

为了消除由于照明光源的非均匀性、镜头渐晕及CCD传感器噪声对图像质量造成的不良影响,首先从理论上分析了线阵CCD固定模式噪声和像素光电响应非均匀性的数学模型和产生的原因;对像素光电响应非均匀性这一主要影响因素,根据其光电响应模型提出了CCD像素光电响应非均匀性的两点校正方法,即求解出各个像素光电响应不均匀性的校正因子和暗偏置量系数,进而用以计算各个像素的校正量,实现逐点校正;针对校正算法大数据量、实时计算的要求,设计了基于现场可编程逻辑门阵列FPGA快速实现校正算法的硬件处理结构。最后,通过仿真和实验表明,两点校正方法可以有效地减小CCD像素光电响应不均匀性的图像噪声,提高图像质量,以便做后续精确处理。

Study on Linear CCD Flat Field Correction and its Implementation on FPGA

Lighting source non-uniformity,lens vignetting and CCD sensor noise are the cause of bad image quality.In order to remove these bad effects,the mathematical model and orgin of FPN and PRNU for linear CCD are analyzed theoretically at first.As for the main factor of pixel response non-uniformity,two-point correction algorithm for CCD pixel response non-uniformity is put forward based on photoelectric response module.The correction factors and dark offset for every pixel is computed to realize calculating correction amount point by point.As for the requirements of bulk data and real-time,FPGA hardware implementation architecture is introduced and designed.The final simulation and experiments shows that the two point correction algorithm can reduce image PRNU noise effectively,and it is helpful for the subsequent precise processing.