Modified Two-Point Correction Method for Wide-Spectrum LWIR Detection System

Abstract

Non-uniformity commonly exists in the infrared focal plane, which behaves as the fixed-pattern noise (FPN) and seriously affects the image quality of long-wave infrared (LWIR) detection systems. The two-point correction (TPC) method is commonly used to reduce image FPN in engineering. However, when a wide-spectrum LWIR detection system calibrated with a black body is used to detect weak and small targets in the sky, FPN still appears in the image, affecting its uniformity. The effects of atmospheric transmittance characteristics of long-range paths on the non-uniformity of wide-spectrum long-wave infrared systems have not been studied. This paper proposes a modified TPC model based on spectral subdivision that introduces atmospheric transmittance. Additionally, the effects of atmospheric transmittance characteristics on the long-wave infrared non-uniform correction coefficient are analyzed. The experimental results for a black body scene and sky scene using a weak and small target detection system with a long-wave Sofradir FPA demonstrate that the wide-spectrum LWIR detection system fully considers atmospheric transmittance when performing calibration based on the TPC method, which can reduce the non-uniformity of the image.

Progress in Active Infrared Imaging for Defect Detection in the Renewable and Electronic Industries

“…CBNUC encompasses a range of algorithms used to mitigate non-uniformity in thermal infrared imaging devices. Representative algorithms in this category include two-point correction (TPC) [51], multi-point correction (MPC) [52], radiometric correction [53], and scene-based non-uniformity correction (SBNUC) [50]. Certain CBNUC methods can provide highly accurate non-uniformity correction, ensuring that thermal images accurately represent temperature differences.…”