红外焦平面阵列的自适应非均匀性校正及硬件实现

Adaptive nonuniformity correction and hardware implementation of IRFPA

针对长时间工作或环境剧烈变化时红外焦平面阵列(IRFPA)器件易产生条纹状非均匀性的问题,研究了在不遮挡成像视场条件下它的动态非均匀性校正(NUC)及其硬件实现技术。介绍了基于场景的改进恒定统计NUC(ICS-NUC)方法,即通过纵向通道间的统计量均衡策略实现对条纹非均匀性的抑制,并引入遗忘因子通过帧间迭代实现非均匀性的动态校正。描述了基于非制冷IRFPA组件在BF561DSP平台的ICS-NUC处理流程,并实现了ICS-NUC的均值法(IC-SA)和中值法(ICSM),从而有效地动态校正条纹非均匀性,提高红外图像质量。实验表明,经过ICS-NUC处理,减弱了红外图像的条纹噪声,使用ICSA和ICSM法使IRFPA组件的非均匀性从3.43%分别降低至1.82%和0.91%,连续运行4h后仍可使组件非均匀性从漂移后的5.05%降至0.92%。提出的方法为后续高性能热成像系统的研究和应用奠定了技术基础。

Infrared Focal Plane Array（IRFPA） is easy to produce a fringe nonuniformity（NU） when it works for long hours or in a changed environment.Aiming at this problem,a dynamic Nonuniformity Correction（NUC） method was proposed in no covering imaging fields and its hardware realization technology was investigated.A scene-based algorithm,Improved Constant Statistics Nonuniformity Correction（ICS-NUC） was presented,in which the fringe NU was reduced by balancing the statistics of vertical channels,and a dynamic NUC was realized by using a forgetting factor in inter-frame iterative process.The ICS-NUC algorithm flow based on an uncooled IRFPA module with BF561 DSP platform was described.Then,two ICS-NUC algorithms,ICS by Average（ICSA） and ICS by Median（ICSM）,were implemented on the platform.By these ways,the fringe NU was corrected dynamically,and whole the infrared image quality was improved.The experimental results show that the fringe NU of IR image is reduced after ICS-NUC and the NU of IRFPA module is decreased from 3.43% to 1.82% by ICSA and 0.91% by ICSM,respectively.After continuous operation by four hours,the NU of IRFPA module is still decreased from 5.05%（drifted） to 0.92% by using ICSM.It concludes that the realization of ICS-NUC algorithm on IRFPA module can lay a technical foundation for the following study and applications of high-performance thermal imaging systems.