Restoration of turbulence-degraded images using pixel histograms


  1. Potvin, G.
  2. Forand, J.L.
  3. Dion, D.
Corporate Authors
Defence R&D Canada - Valcartier, Valcartier QUE (CAN)
The two most noticeable distortions caused by atmospheric turbulence are the displacement and the spreading (blurring) of the irradiance in the image plane. The displacement is when the irradiance that would arrive at a certain point in the image plane if there were no turbulence actually arrives at a certain distance away from it. The spreading (or blurting) is when the irradiance that would arrive at a certain point is actually spread out around that point. For a wide field-of-view imaged over a long horizontal path in the surface layer, these effects vary over space and time and cause straight edges to appear wavy with variable blur. An example of this can be seen in part (a) of 10 cm aperture. It used exposure time of 4ms, at a rate of 250 fps and over a period of 8 s. The target is a black and white panel 3 m wide by 1.5 m high located 1 km away. The sequence of images was taken as part of a land trial organized by the NATO group SET-072/RTG-40 on Modeling Active Imaging Sensors. The trial took place at the High Energy Laser Systems Test Facility at White Sands Missile Range, NM, 14-18 November 2005. Part (b) of Fig 1 shows the average image over the entire sequence. We notice that although the edges are straight, they are also quite blurry. This is due to the blurring of the individual images, but also to the displacements which create as an additional blur in the average image. To eliminate blurring, Glick et al. [1] proposed the use of the most-common (or modal) gray
Report Number
DRDC-VALCARTIER-SL-2010-037 — Scientific Literature
Date of publication
21 Apr 2010
Number of Pages
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