This is a description on how to perform colour calibration of a camera and photo settings under Linux using the UFRaw raw format handler, the QPCard 201 calibration chart and Argyll Color Management System.
After struggling with LPROF and failing to make it work for me (see this how-to), I've reworked my work flow for colour management to incorporate Argyll Color Management System instead. This had the positive side effect that I could make my own script that provides the fast and effortless production of a temporary profile for every photo session.
In a related how-to I described how to use the ICC profiles that come with Canon Digital SLR (EOS) together with UFRaw to digitally develop colour calibrated photographs. This how-to will describe how you can use the QPcard 201 and Argyll Color Management System to create your own ICC profile that describes the lighting conditions of a photo session. With modification this guide can be used to produce a profile from other charts as well, of course, such as the Gretag Mcbeth. This profile can then be used to further correct the colour of you pictures.
In figure 1 there is a photograph with the QPCard201 used to calibrate the colours. There is also a set of close-up images showing the results from using the custom profile from this how-to compared to some profiles that came with the camera. The general profiles required manual white balancing and exposure adjustments to get this close to the custom profile.
In my work flow I use
To put this together I used the following resources
scanin
and colprof
)See also:
ufraw-batch --conf=$HOME/.ufrawrc.make_profile myimage.cr2 \
--out-type=png --output=/tmp/custom_profile.png
convert /tmp/custom_profile.png /tmp/custom_profile.tiff
scanin
to extract the colour values from
the chart in the image. The following line works for me and
gives a nice diagnostics image.
scanin -dioa -G 3.0 /tmp/custom_profile.tiff \
$HOME/cms/qpcard201.cht \
$HOME/cms/qpcard201.cie
display diag.tif
colprof
colprof -ag -qu -b n -y /tmp/custom_profile
mv /tmp/custom_profile.icc /tmp/custom.icc
rm /tmp/custom_profile.*
ufraw --conf=$HOME/.ufrawrc.use_profile myimage.cr2