Colouring utility for composing of frames in natural colours.
munipack coloring [options] [file(s)] ...
Munipack implements a method which transforms images taken via
a set of standard photometric filters (Johnson BVR or an equivalent)
to CIE 1931 XYZ
colour space ― sensitivity of the human eye.
Main purpose of the utility is to offer possibility to create images
in natural colours from instrument not equipped by CIE 1931 XYZ filters
(eg. any astromical telescope).
Results has colours near of natural colours and simulates how the object
would be seen by an extraordinary observer, like a huge digital camera.
If the input frames are calibrated, or ctph is specified,
the output colour frames has absolute calibration in intensities
(energy carried by photon rates). To partialy preserve values,
the frames are keeped in energy rates in electronvolts per second,
square meter and square arcseconds (rather than W/m2/srad as
There are important difference between common digital detectors
(CCD, cameras) and human eye: the human eye detect energy, whilst
these are photon detectors.
RGB colour space
CIE 1931 XYZ has been selected as the default output colour space
due compatibility with dcraw. Also, the colour space is
very near to Johnson giving more accurate transformation matrix.
Much more, CIE 1931 XYZ is ideal for additional processing due
wide common CIE Luv, CIE Lab.
In contsrast, sRGB or Adobe RGB are very specific spaces,
non-linear and very difficlout to modify. They are considered
as final product, whilst CIE 1931 XYZ are intended for additional
Input and output
On input, a list of frames is expected.
The frames should be specified in short wavelengths first order
(conventional BVR order) on command line,
this is oppposite to RGB (XYZ).
The filters in headers should be specified exactly as B,
characters for Johnson's system, no aliases are allowed.
Specify the colour-space of input images (eg. 'Johnson BVR').
If the value is not given, passed frames are scaned for filters,
and the colour space is guessted from them.
Specify the final colour space identification. 'CIE 1931 XYZ'
is used by default. Anotehr possible value is 'Johnson BVR'
which can be usefull for additional processing, like
tunning in xmunipack.
-w, --weights w1,w2,...
Gives weights of particular colour bands. There are no limitation
on weights except: all of them must be possitive numbers, their
count must corresponds to passed input frames.
-q, --ctphs ctph1,ctph2,...
Gives reciprocal quantum efficiency for particular colour bands.
The values can be determined by photon calibration.
Generally, it is proper characteristics of given aparatus
(detector, filters and telescope), but slighly varies with
-b, --backs back1,back2,...
Gives background levels of particular colour bands on input frames.
By default, medians of image levels are used. It is very good
star point for fine tune, in case of astronomical frames.
Disables estimation of backgrounds levels. It is helful
for non-astronomical frames.
Specifies coordinates in pixels of a spot of circular
shape with a radius (default 7 pixels). The spot is a white
part of frame, robust mean in particular filters is used
to determine weights.
Specifies coordinates in pixels of a star considered
as a white star (stars with temperatures 10 thusands
kelvins, with B-V = 0 or spectral class A0).
An aperture of circular shape with a radius (default 7 pixels)
is used to determine the total flux in particular filters
and to determine of weights.
This option is there mainly to give a prove that it works,
calibrated frames gives better results and are easy to use.
Specifies radius of the aperture (for star) or the spot
for determination of white colour. By default, it is 7 pixels.
Prints a table with available colour space transformations.