Correction of distortions and improvement of information content in
satellite-acquired multi spectral images
V. I. Voloshyn and V. M. Korchinsky
For a brief description of the methods employed in the present study, we perform
image reconstruction from employing one reference image selected within the
spectral range under consideration. The reconstruction is performed using an
information-geometrical model describing the physical process of image
formation in the short wave range of electromagnetic spectra (visual and
neighboring infrared). The reconstruction of image pixel intensities is
performed by arranging in ideal projection planes (PP) the locations needed for
representation in different spectral channels to analyze and validate the
available data. The model for reconstruction of the multispectral
images was developed from physical principles. Scanner method was applied with
coordinate-susceptibility photoreceivers (CSPR). A
physics-based model for the formation of multispectral
raster images with CSPR scanners in the electro-optic and infrared ranges can
be developed by taking into account the tuning of optic-mechanic scanner
scheme. By using basic optic principles, the conformity between points on
the earth surface and scanner sensitivity element (SE) can be established.
One may note that each SE is fixing the electromagnetic radiation from some
site as any cell projection on the earth surface where the center of projection
is situated in the optic object-lens center.
Integration is performed on each cell square. This gives the mathematical model
for the formation of digital images from CSPR equipped scanners in the multi
spectral regime. It also enables explaining the reasons for distortions in
these images. It may be noted that different projection distortions caused by
optic-mechanic tuning scanner lead to displacements at the subpixel
level. Due to construction peculiarities characterizing the satellite and the
sensor, the intensity distribution captured on the image plane will suffer
distortions due to mixing of images collected along the different spectral
channels. A method for the correction of distortions is to select the intensity
distribution on one channel as the basic image and construct the intensity distribution
data on other channels by image processing operations. Thus the method offers
correction in the case of point displacement between different spectral
channels due to diffraction effects and spatial coordinate-susceptibility of
photo receivers causing positioning instability during sensing.