提出一种基于现场可编程门阵列(FPGA)的时间延迟积分(TDI)CCD图像实时处理方法以提高拼接成像系统输出图像的质量和视觉效果。首先, 对TDICCD成像系统进行像元级非均匀性校正, 去除像元响应差异、固定图形噪声和暗电流噪声; 对图像进行了基于行极值的自适应中值滤波, 去除了图像中的随机噪声和脉冲噪声。然后, 对噪声处理后的图像进行图像增强, 通过提取图像的低频和高频成分, 实现图像细节信息的调整和对比度增强。最后, 采用基于行的分段线性拉伸方式, 提高图像的动态范围。设计了基于FPGA的TDICCD成像系统的图像实时校正处理结构, 分析了算法占用的资源、算法计算误差和可靠性等指标。实验结果表明, 提出的图像实时处理结构将图像输出信噪比均值由48 db提高到52 db, 图像非均匀性由3.41%降低到1.73%, 图像的对比度显著增强, 其动态范围提高了6%.

A real-time image processing method based on a Field Programming Gate Array(FPGA) was proposed for Time Delay Integral( TDI)CCD space mosaic camera to improve its imaging quality and visual effect. Firstly, the TDICCD imaging system was corrected in a non-uniformity mode by a pixel level,by which the fixed-pattern noise and dark current noise were eliminated. Then, an adaptive median filter based on the inline max-min values was proposed to eliminate the random noise and pulse noise. Furthermore, an image after denoising was enhanced in the TDICCD image. By extracting the low-frequency part and the high frequency part of the image, the detail adjustment and contrast enhancement of the image were implemented. Finally, a linear stretching method based on image line data divided was proposed to improve the dynamic range of the real-time imaging system. Moreover, a real-time image processing method for the TDICCD space mosaic camera based on FPGA was designed, and the synthesized resources, algorithm errors and reliability in the FPGA were analyzed. The experimental results indicate that the average SNR of the imaging system has been improved from 48 db to 52 db,and the non-uniformity decreased from 3.41% to 1.73% within a TDICCD. The image contrast is enhanced greatly and the dynamic range is prompted by 6% in the self define criterion.