Siril Fits header not displaying NAXIS3 on single image

Software Siril
1

Hello, I have been attempting to open ASI2600MC camara single Fits files in Irfanview program (with out success) for lite checking/culling prior loading into Siril for stacking.
When I tried to open the file in Irfanview it only displays in Black & White. I contacted Irfan at Irfanview and he pointed out that my file did not have NAXIS3 in the header.
On checking, using Siril, I found that the stacked image had NAXIS 3 Number of Axis. Also NAXIS3 Number of axis 3 in another line (Salmon Coloured lines)
When I open the single image in Siril it opens in Black & White with (B/W) in top left hand corner, looking in the Fits header there is no NAXIS 3 Number of Axis. Also NAXIS3 Number of axis 3 in another line (Salmon Coloured lines)
Not sure why single images are opening/displaying in black & white?

Thanks, Kevin

Screenshot 2026-05-01 123653
Screenshot 2026-05-01 1236531855×917 1.38 MB

Screenshot 2026-05-01 123829
Screenshot 2026-05-01 1238291914×955 647 KB

2

If your image comes from osc, you need to debayer the single image first.
Well, this is basics and I would recommend to read our documentation. It explains how to do it

3

Thanks lock42,
Not sure how to do that but will attempt to read documentation.
But which documentation Irfanview or Siril?
A bit disappointed that no one has posted on how to actually debayer image. As stated I’m a newbie and technologically challenged.
K

4

Siril tutorial, the one for beginners: Siril - Manual pre-processing

5

Thanks for info, will give it a go
K