When I do a photometric color calibration on the dark shark nebula I get this red tint, PCC red tint — Postimages
On every other image it works well just with this one I get this issue. Any idea?
Hello, there is a tab containing logs in Siril, this will probably give you a hint. In general, it fails because the input image is either negative or not made with red, green and blue filters.
Edit: your log says it only could use 8 stars and for some reason the computed factors are very bad. 8 stars is not enough, most are either saturated or have negative surroundings. Look at the image statistics. You may try increasing the magnitude used for the stars to get more of them.
I changed the magnitude from auto to manual and changed the value from 12 to 18. And it works now, thanks. I did notice it takes a lot longer to finish but that’s ok. PCC red tint fixed — Postimages
18 was kind of extreme 
55572 stars is a bit much, but at least it worked.