That's a wicked shot! Honestly, a data set and object like this has no place in the beginners section anymore
Many, many great tips here already. Once you're comfortable with all these great pointers, you may want to try & get your head around masks/layers and working on your data selectively. It's what the greats like Ken Crawford do.
When it comes to color correction; trust your data. Try to understand exactly why things look the way they look. If your colors are off (which is almost always the case), chances are there is something polluting the signal (light pollution, secondary reflections, IR or UV fuzz, etc.) Methodically find the causes and simply remove the isolated pollution from the signal. Pixel math will help you here. Once you have subtracted all polluting influences, chances are you will be left with something close to the real colors of the object. A lot of people seem to struggle with color correction; it's not magic, just science!
One last tip on color correction is that some objects in the sky are perfect samples to calibrate your white balance against (notably a lot of galaxies).
If you use an OSC or DSLR and you have oversampled your data (e.g. the CCD resolution was higher than the scope could resolve under the seeing conditions at the time - or in laymans terms, your image looks blurry due to seeing), then use software binning to reclaim signal fidelity by trading in resolution. Many DSLRs and compact cameras these days have the exact same option. They call it something like 'low-light' mode and it is the reason why they can attain these high ISO ratings; they trade in resolution.
I took you dataset and put it through StarTools. Here are some of the steps;
- Binned it to 71% (2x noise reduction)
- Had the CPU have its way with the levels (manual Curve/histogram manipulation is sooo last decade
).
- Modeled the light pollution (at least I assume it was light pollution - a signature orange glow) and subtracted it. After that no color correction was necessary (a good sign), although I did bump up the saturation a bit.
- Then applied a lens correction model to the image. This sorted out the worst of the distortion.
- Cropped the image to center Centaurus A.
- Created a mask with just Centaurus A, minus halo and applied a tiny bit of deconvolution to it.
- Created another mask to preserve Centaurus A + halo.
- Applied a median filter, combined with a luminance mask to modify only the darkest parts (deep space noise reduction).
- Selected all the stars and put them through the Repair module to warp them into perfectly round shapes.
- Applied a touch of Synth (8" refractor - I wish!) to the stars to soften them up a bit.
- I'm sure I forgot some steps here.
I didn't bother with the star colors too much - I like how it keeps the focus on Centaurus A as the only distinctly colored object.
Great image and I hope to see more in the Deep Space section!
