Messier 22

Acquisition:

Some subs under Bortle 6-7 skies, some under Bortle 2
Nikon D7000 camera
Orion Apex 102mm telescope, 1300mm focal length
Orion AstroView EQ3 with single-axis drive
30s x 29 frames
f/12.7
ISO 1600

Processing:

Siril:

Manual background/highlight color calibration
Background extraction
Modified asinh histogram stretch
Saturation
Histogram midpoint adjustment

RawTherapee:

L*a*b chrominance/luminance (to reduce chroma noise)
Luminance noise reduction

GIMP:

Luminance curve adjustment
Saturation
Temperature increase (too blue)