Hi Paul,
I had a look at the data set in StarTools. I actually couldn't produce the magenta cast - any chance you could share your workflow with us, so we might pinpoint what caused it?
What I did notice though was that the data has been pre-colorbalanced. This introduces anomalous colour in the highlights (because colour balancing necessitates clipping). DSS does not seem to respect settings telling it to keep its hands off the colour data as recorded
As a work around, you could use dcraw from the command line (see correct parameters elsewhere).
Another thing I noticed were some dust donuts that were not corrected by your flats.
The image you posted is indeed a little on the blue side. However, this image should be really easy to color balance in fact; it is a milkyway type galaxy, its aggregate pixels being a good whitebalance source. Add to that a nice evenly distributed star field (in terms of temperatures) and the whole image becomes the perfect calibration source! (marred only a by DSS butchering the colour information in the highlights)
What you'd be looking for in terms of this image and NGC6744 are (as mentioned) a good even distribution of all star temperatures from red->orange->yellow to white and blue, and, in terms of the galaxy, a bluer outer rim (younger stars due to more star formation), a yellow core (older stars due to less star formation) and the presence of HII areas/knots (predominantly emitting on the Ha and Hb wavelengths which turns up a purplish/pinkish colour). Evidence of the latter is visible, but it's not much.
This is all assuming you care about your colour information conveying interesting information to the viewer of course
If you want to stretch and mangle your colour information along with your luminance (like most people/software) all bets are off of course...
All this is also assuming that all you're capturing is the visible wavelengths. Since your camera has a modified spectrum (correct?) you will be capturing more red and below, though I cannot immediately see evidence of increased sensitivity.
Quick result here;
http://www.startools.org/download/Tu...ul_NGC6744.jpg