Adaptive nonuniformity correction and hardware implementation of IRFPA

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.