With version 4.2,
eXcalibrator supports PixInsight (PI) 32-bit floating point and both
16-bit signed and unsigned FITS files. This document assumes that
the reader is familiar with eXcalibrator.
PixInsight offers multiple
options for the FITS format. This introduces two problems for
eXcalibrator, data scaling and the vertical flip. To keep things simple, eXcalibrator assumes
that the files are created with the PixInsight default settings.
EXcalibrator only checks the WCS File for the use of PI images.
In the case of 32-bit floating-point data, PI scales the
pixel values from 0.0 to 1.0. Internally, eXcalibrator equally rescales
the three color files to 16-bit data.
The Vertical Flip
PixInsight allows the user
to choose how
FITS images are displayed. The default method is
with no vertical flip. The dialog window, in Image1, shows the default
settings. The Upper Left Corner selection displays a FITS image without
a vertical flip. This agrees with most amateur astronomy software,
With the Lower Left Corner
setting, PI displays the image flipped vertically. Apparently, this
method is preferred by the professional astronomers.
To display the PI FITS Format
Preferences window click View | Explore Windows | Format Explorer and