All images and text provided by Dirk Fuchs
general remarks:
- image processing is more an art than science
- each image is different, there is no general workflow, noautomated solution for all
- don’t give up: when you’re not satisfied with the, step back and restart, quite often several iterations are required
- for tipps and tricks watch youtube tutorials (there are many)
- useful software: Siril, starnet++ for separation of stars and starlesss image (can be integrated in Siril), GraXpert, Photoshop Elements, GIMP
- finally: Don’t overdo constrast, saturatio etc. —> Less is more!
steps:
1.pre-selection of lights with ZWO FITS-viewer (sorting out bad quality like temporary faint clouds)
2.stacking in Siril (by script)
3.basic porcessing in Siril:
- colour calibration (SPCC)
- background extraction
- star removal
-
unlinked autostretch
Remark to stretching and colour management:
Many nebula are dominated by Ha emissions leading to a mostly reddish image.
If you want to show bluish/greenish colours in your final image it is important to do an unlinked stertching.
At this point the image looks as follows:
5. Improving brightness, contrast, saturation and sharpness in Photoshop Elements. Denoising again with GraXpert.
Now the image looks as follows:
Looking decent already.
However we want to show more the bluish tone of the oxygen emissions.
6. Colour management in Photoshop:
Making a copy layer and turning the colour temperature more to towards blue:
Now this is a bit too much of blue.
Now blending only a percentage of the bluish version into the „true“ colour version (maybe 50%):
Now we are pretty much done.
7. Remcombing the processed starless image and the (separately stretched starmask) in GIMP.
Check and correct colour balance for the background in GIMP. It should be neutral, not bluish.
8. Some subtle finetuning in Photoshop for the final result.
Huge thanks to Dirk Fuchs for sharing his post-processing workflow! 🙌✨