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Color-space Transformations

Color-space transformations


munipack ctrafo [-o file] [-c colorspace] [-ct cstable] file black1,weight1 ...
munipack ctrafo [--list]


Transform a color FITS file (specified as the first non-optional parameter) to a new colorspace given by -c option.

The --list option lists all possible known spaces.

With -ct you can specify a file with addtional transformations. The format of the file is described in sources.

The mandatory parameter is black (weight is optional) for every band in the input FITS. But, ones are currently used only for the transformation to CIE 1931 XYZ colorspace. Both must be determined empirically. It is recommended for black to use level 1-sigma under median for typical night sky images. The weight is proportional to the recorded flux, so choose weight by the reciprocal relative ratio of exposure times.


-c color-space
Color-space of the output image
-ct color-space table
Table of known color-spaces
List of predefined color-spaces

See Common options for input/output filenames.


Convert a color FITS image to a new colorspace. The black levels are 10 thousand (in B), 24 thousand (V) and 52 thousand (in R). The blue filter we get with 0.66 weight:

$ munipack ctrafo -o m27_xyz.fits -c 'XYZ' m27.fits 1e4,0.66 24e3,1 52e3,1
Dumbell nebula in colors

See Also

Color Processing, Common options