Diagnose 21 of 29 Processing
Green cast
The whole image has a green tint, worst in the background.
A labeled frame from our own archive, with its acquisition data, is coming to this page.
- At 100 %
Empty sky between the stars, after stretching. It reads green where it should be a neutral gray.
- Causes, most likely first
No color calibration
Without a color calibration step, the image keeps the camera's raw color balance.
FixRun a color calibration on the linear data. Siril's SPCC does it in the free chain.
No green-noise removal
Some green noise can remain in the background after calibration.
FixApply a green-noise removal step after color calibration.
One-shot color camera without proper white balance
A one-shot color camera's raw data has no white balance applied, so it has to be set in processing.
FixSet the white balance in processing. A star-based calibration such as SPCC sets it from the stars in the frame.
- Looks like, but isn't
A light-pollution gradient ramps across the frame. A green cast tints it evenly.
- One frame can't tell you
The finished image shows the cast. Whether it is in the data or came from processing needs the linear stack, before and after color calibration.
- How to confirm the fix
A neutral gray background after calibration, with no green left under a hard stretch.
- Sources
In the symptom picker
- The whole image has a green tint, worst in the backgroundweight 3
Tools for this
- Processing Pathnot built yet
Last updated All 29 failure modes, and the symptom picker