iKarus StellarMate X - Page 54

The StellarMate X Manual
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Sigma clipping helps with noise reduction during the stacking process. The mean and
standard deviation are calculated from the first three captures. Subsequent captures are
then sigma-clipped to remove any outliers outside the envelope of acceptable ranges
around the mean.
The diagram below shows how values outside the envelope are masked and not included
in the stacking process. You can control the upper and lower limits of this envelope by
adjusting the s
lower
and s
upper
(default is set to 3) parameters in the app.
The contrast and saturation controls do not affect the stacking process itself, but apply
some cosmetic adjustments to the final image to improve its quality. Some non-nebulae
objects might benefit from the automatic background subtraction controlled by the
Background parameter. Increasing this value would attempt to compensate for sky glow in
the background, but might also result in loss of detail.