MallinCam Universe User Manual page 33

The next image was captured with a luminance filter installed. Note the difference in the overall
color balance of the scene. This second image is quite a faithful reproduction of the actual view,
again, with no post-processing involved.
In both cases, the One-Push WB function adjusted the Red, Green, and Blue gain sliders in a
similar fashion, though by different amounts, and with obvious differences in the end results.
For the second image, the Red slider was decreased to only 0.97, the Green slider was left at the
default value of 1.00, and the Blue slider was increased to 1.79.
Astronomical imaging is understandably different than terrestrial imaging. In terrestrial imaging,
most of the light in an image is reflected light, coming from a source like the sun or man-made
lighting. In astronomical imaging, most of the light is being emitted by your target of interest,
such as a nebula, galaxy, or star cluster. But the same principle applies. In both cases, the color
balance of the image needs to be adjusted for proper color rendition. You can correct the balance
to a degree afterwards using an image processing application, but this may not yield very good
results if the original captured color balance was considerably off to begin with.
With astronomical imaging, the One-Push WB function can provide a good initial starting point
if your target is fairly large and bright. However, it may be limited in its analysis for lesser
targets. As a suggestion, you may want to set the color sliders manually, similar to the terrestrial
example above (Red ~ 1.00, Green = 1.00, Blue ~ 1.80). This assumes that you're using a
luminance or light pollution reduction filter. If not, then perhaps try Red ~ 0.75, Green = 1.00,
and Blue ~ 1.50 as a starting point. Keep a record of your results. When you find a combination
that works for you, try using it on various target types. You might even want to compare your
images with the works of other experienced astro-imagers as a reference point.
While these suggestions should help you get closer to a truer color balance, there are other
factors at play that will be unique to your situation. For instance, the optimum color balance will
be affected by the specific manufacture of any filter that you use and by the optics of your
telescope. A full discussion of attaining proper color balance is beyond the scope of this guide,
but there are many good sources of information available on the Internet to help you out.
One technique you might consider is to take an image through your telescope of a standard
photographic gray card illuminated by a white light source. You can then adjust the color gain
sliders to try and match the gray shade in your capture with the actual card. But note that such a
comparison will also be strongly influenced by the monitor you're viewing the image on.
Color calibrating your monitor is highly recommended for this purpose.
MallinCam Universe - User's Guide v1.05 33