Retinex Image Processing--Publications--SPIE 6246, Orlando, Florida
Conference
A Comparison of Visual Statistics for the Image Enhancement of
FORESITE Aerial Images with Those of Major Image Classes
Daniel J. Jobson, Zia-ur Rahman, Glenn A. Woodell, Glenn D. Hines
Abstract
Aerial images from the Follow-On Radar, Enhanced and Synthetic Vision
Systems Integration Technology Evaluation (FORESITE) flight tests with
the NASA Langley Research Center's research Boeing 757 were acquired
during severe haze and haze/mixed clouds visibility conditions. These
images were enhanced using the Visual Servo (VS) process that makes use
of the Multiscale Retinex. The images were then quantified with visual
quality metrics used internally within the VS. One of these metrics, the
Visual Contrast Measure, has been computed for hundreds of FORESITE
images, and for major classes of imaging---terrestrial (consumer),
orbital Earth observations, orbital Mars surface imaging, NOAA aerial
photographs, and underwater imaging. The metric quantifies both the
degree of visual impairment of the original, un-enhanced images as well
as the degree of visibility improvement achieved by the enhancement
process. The large aggregate data exhibits trends relating to degree of
atmospheric visibility attenuation, and its impact on the limits of
enhancement performance for the various image classes. Overall results
support the idea that in most cases that do not involve extreme
reduction in visibility, large gains in visual contrast are routinely
achieved by VS processing. Additionally, for very poor visibility
imaging, lesser, but still substantial, gains in visual contrast are
also routinely achieved. Further, the data suggest that these visual
quality metrics can be used as external standalone metrics for
establishing performance parameters.
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