Nonuniformity Correction

Scene-based non-uniformity correction example. The raw uncorrected frame is shown on the left. Using only 5 frames, and no calibration targets of any sort, the non-uniformity correction is performed [3]. The corrected frame is shown on the right.

The Problem

Focal-plane array (FPA) sensors are widely used in visible-light and infrared imaging systems for a variety of applications.  An FPA sensor consists of a two-dimensional grid of photodetectors placed in the focal plane of an imaging lens.  The performance of FPA's are known, however, to be affected by the presence of spatial fixed-pattern noise that is superimposed on the true image.  This is particularly true for infrared FPA's.  This noise is attributed to the non-uniformity in the photoresponses of the individual detectors in the array.  Furthermore, what makes overcoming this problem more challenging is the fact that the non-uniformity drifts slowly in time. This drift is due to changes in the external conditions such as the surrounding temperature, variation in the transistor bias voltage, and the variation in the collected irradiance. 

Recently, there has been considerable research focused on developing nonuniformity correction (NUC) techniques that use only the information in the scene being imaged (no calibration targets).  The scene-based NUC algorithms generally use an image sequence and rely on motion between frames.  We are working on a number of novel scene-based NUC techniques.  Some of these are based on accurate motion estimation and others utilize custom nonlinear spatial filters.

Selected References

1. R. C. Hardie, F. Baxley, B. Brys, P. Hytla, “Scene-based Nonuniformity Correction with Reduced Ghosting Using a Gated LMS Algorithm,” OSA Optics Express, Vol. 17, No. 17, pp. 14918-14933, August 2009.

2. R. C. Hardie and D. R. Droege, “A MAP Estimator for Simultaneous Super-Resolution and Detector Nonuniformity Correction,” EURASIP Journal on Advances in Signal Processing, Volume 2007, Article ID 89354, 11 pages, doi:10.1155/2007/89354.

3.  B. Narayanan, R. C. Hardie, R. A. Muse, "Scene-based nonuniformity correction technique that exploits knowledge of the focal-plane array readout architecture,” Applied Optics, Volume 44, No. 17, June 2005 , pp. 3482-3491.

4. B. M. Ratliff, M. M. Hayat, and R. C. Hardie, "An algebraic algorithm for nonuniformity correction in focal-plane arrays," The Journal of the Optical Society of America A, Vol. 19, pp. 1737-1747, September 2002.

5. R. C. Hardie, M. M. Hayat, E. Armstrong and B. Yasuda, “Scene Based Non-uniformity Correction Using Video Sequences and Registration,” Applied Optics, Vol. 39, No. 8, March 2000, pp. 1241-1250.

6. R. A. Muse and R. C. Hardie, “A New Non-uniformity Correction Technique Based on Readout Architecture in Focal Plane Arrays,” The 6th World Multiconference on Systemics, Cybernetics and Informatics, Invited Session on Image Processing for Infrared Array Sensors: Nonuniformity Correction and Registration, Orlando FL, July 15, 2002.

7. R. C. Hardie and M. M. Hayat, “A Nonlinear Filter Based Approach to Detector Nonuniformity Correction,” Proceedings of the 2001 IEEE-EURASIP Workshop on Nonlinear Signal and Image Processing, June 2001, Baltimore MD.

   1.  E. E. Armstrong, M. M. Hayat, R. C. Hardie, S. Torres, and B. Yasuda, “Non-uniformity Correction for Improved Registration and High-Resolution Image Reconstruction in IR Imagery,” Proceedings of SPIE’s Annual Meeting, Application of Digital Image Processing XXII, Denver Colorado, July 18-23, 1999.