B.D. Walters’s research while affiliated with University of Johannesburg and other places

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Publications (2)


Sharpening and contrast enhancement of atmospheric turbulence degraded video sequences
  • Conference Paper
  • Full-text available

January 2010

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36 Reads

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5 Citations

B.D. Walters

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Long range imaging systems that capture video through the atmosphere face a major problem in the form of atmospheric turbulence. This turbulence causes a phenomenon called heat shimmer which appears as a blurring and a wavering geometric distortion of the target scene which limits the effective range of the imaging system. We explore an image processing approach to mitigating the blurring effect of this distortion by using a blind deconvolution technique to sharpen the video signal and a dynamic illuminance-reflectance correction technique to improve the signal's contrast. The algorithm is implemented on a Graphics Processing Unit to achieve near real-time performance.

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Comparison of two terrestrial atmospheric turbulence suppression algorithms (March 2007)

October 2007

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4 Reads

This paper describes the problem of capturing video through turbulent atmosphere (also referred to as heat shimmer or heat scintillation) and describes some of the existing methods used in an attempt to counteract the problem. Within this problem of imaging through turbulent atmosphere there is a distinct lack of comparisons between methods and a reliable metric for digital images. This paper contributes through the selection of two algorithms which are implemented, tested and compared, one a power spectrum restoration approach from the early 1990's and a newer image registration and fusion based method. The results show the ability of the old power spectrum method to stabilize the image although local object motion presents a problem, as well as the computational complexity of the image registration method.

Citations (1)


... The interpolating splines provide the continuity constraints, therefore resulting in a smooth warp. Figure 2 shows two frames and their difference image from a real-life long-range surveillance video sequence termed the Building-site sequence [20]. When played, it is a very good example of what is observed under turbulent conditions. ...

Reference:

Simple and efficient approach for restoration of non-uniformly warped images
Sharpening and contrast enhancement of atmospheric turbulence degraded video sequences