Abstract. The distinction of objects in images obtained in different ranges of
electromagnetic waves depends on the presence of atmospheric formations, for
example, hydrometeors (fog, snow, rain). This topic is relevant and issues
related with it, are raised in many works.
The
distortion of the image by hydrometeors in some cases is described as the sum
of two correlated factors - the absorption of radiation coming from the object
and illumination by the scattered radiation of the atmosphere. However, the
high quality of image restoration requires a lot of time for image processing.
Another
way to combat distortions, caused by hydrometeors, is to increase the contrast
by converting the dynamic range of image brightness. This method only partially
compensates for distortion.
In
order to correspond to real conditions better, it is necessary to supplement
the model of propagation medium by scattering radio waves on the path. This
implies, in addition to the necessity of increasing the contrast, to
reconstruct the image, distorted by the hardware system function (HSF), which
simulates the scattering indicatrix.
In
the first approximation, as the scattering model we take the Gauss HSF with
relatively small but initially unknown width. Thus, the general problem is
divided into two stages - increasing the contrast and restoring the image,
which has been distorted by unknown HSF scattering.
In
our arsenal of tools for image reconstruction there is a method of
renormalization with limitation (MRL). It not only allows you to restore images
distorted by a known hardware function in the presence of unknown interference
and noise, but also produces a recovery with an unknown HSF. In the latter
case, the possibility of a successful solution of the problem is determined by
the fact that the amplitude spectrum of the image which is improved, renormalized
to the universal reference spectrum model (URS).
In
the suggested work, a new proposal is to use the spectral approach with
application to the problems of improving the distinguishability of objects in
images in the presence of hydrometeors, and there is an additional possibility
of combating scattering, which, with a high probability, can occur on
observation tracks.
It
is shown, that without taking into account scattering effects it is not always
possible to reconstruct the images obtained in the presence of hydrometeors.
The spectral approach to solving problems of increasing the discernibility of
details in images distorted by hydrometeors gives additional opportunities in
new areas of applied applications.
Key words: spectrum, renormalization, images distorted by
hydrometeors.
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