Thanks for your attention. I did not mention that I have been doing visual astronomy for ~ 20 years at this point, but astrophotography is relatively quite new (~ 1 year +).
So I am still learning many things. I have had many issues with setting up the scope and photography platform and learning to operate it. So I have not spent much time at all on the
results end and the post picture processing side of this. So I am really not familiar with all the abilities of the FITS viewer and stumbled into them very recently, like I said. My opinion of
the FITS format has gone up considerably in the last week or so and I really appreciate that kstars / ekos seems to be doing a serious job filling out the header information. And I do appreciate
the histogram functions, but I still need some more explanation of that. So when I saw the single channel output and noted it was red only, I thought there was a problem. After looking at it and
working with it more, I understand now and it makes sense that the capture process would create a single channel picture with all the data in that one array. The debayer pattern is there and shows
rggb and I can now see that when I invoke debayering in the view (one way or another) the viewer then shows me all 3 channels like I would expect. So I think everything works, and I understand more now. So I won't post a picture, because I do think everything is normal and expected now. I am still confused about the histogram. This may be partly because I have seen and worked with the asi-air product (my astro friend has and uses several of them) and their histogram, in which you can stretch and restrict the color frequency range of the preview picture before you save it. He manages to take relatively great pictures, preview only, and frequently skips the whole stacking / picture post processing stuff. And yes, He has spent a lot of money on his platform to be able to do that. I prefer your approach because it really supports Linux, supports many vendors cameras, and I very much like having full access to the raspberry pi, which asi-air does not allow. I believe that your FITS viewer histogram shows intensity along the bottom of the graph and since my camera is doing 14 bit a2d conversion (0-15k) I can see essentially how much signal I captured in the picture, allowing me to decide if I could capture longer or if I am reaching saturation. The frequency on the left side is the one I don't really understand. I generally see (after debayering) all three channels spanning the frequency range to similar but differing amounts. I know that r g and b have specific and separated frequency ranges and the bayer filter inside my color camera restricts the specific pixels to those ranges. So I think the frequency scale you show on the left side is some other kind frequency and since its units are not really disclosed, I'm not sure what we are trying to tell me about frequency.
Please let me know what you think about the histogram and frequency.
Thanks VERY much!