Messier 27 (Dumbbell Nebula or Apple Core Nebula)

Acquisition:

Bortle 7 skies
Nikon D7000 camera
Orion Apex 102mm telescope, 1300mm focal length
iOptron CEM26 mount
30s x 249 frames
f/12.7
ISO 400

Processing:

Siril 1.2.0-beta2:

Background extraction
Photometric color calibration
Starnet v2, using generalised hyperbolic transformation on background and stars
Manual histogram stretching

RawTherapee:

L*a*b luminance-hue (LH) adjustment
L*a*b chrominance-luminance (CL) adjustment
Luminance noise reduction

GIMP:

Luminance curve adjustment
Saturation