Unexpected Behavior in Astrophotography Stacking

[RTSullins]

I have a large number of solar photos I want to stack.

If I open one of the photos using the regular Ctrl-O it looks fine.
If I start an Astrophotography Stack and add files (or even just one,) the image looks wildly over exposed.
See image below, what am I doing wrong?

[stokerg]

Hi @RTSullinsand Welcome to the Forums,

Can you upload the images you are working with to our Dropbox here and I can take a look at why this is happening.

[RTSullins]

These photos were taken by a Vanois Vespera <https://vaonis.com/product/vespera-observation-station>

Through user forums, I've learned that other Vespera users have successfully stacked solar photos using AffinityPhoto2.

BTW, I have ~6,000 images from this acquisition sequence that I would like to stack.

[stokerg]

Hi @RTSullins, 

For Astrostacking to work, you'd need a number of other files, as outlined on this link.  Do you have a collection of Dark frames, light frames ect or do you just have the JPGs?

[RTSullins]

Thx for your reply.

Unfortunately, the Vespera does not provide (or allow for) darks, flats, etc. Nevertheless, I've successfully used
AP2 for rudimentary deep sky stacking. It would be way better if I had the other files, but I don't. I have used AP2's
astrophotography stacking on my more classic rig's output, and I've been very, very happy with the results.

For this situation, JR in a reddit post, just showed me that my jpgs are 8-bit and that the astrophotography stacking
of AP2 requires 16-bit images. He suggested that I use regular stacking, which did the trick.

I might suggest to you that astrophotography stacking might automatically reject opening 8-bit files.

I would like to say that I'm new to AP2 and I'm enjoying it immensely. I'm a long-time user of ACDSee and I only left it
when I learned of the astrophotography features built into AP2. Further, I'm enjoying JR's astrophotography macros,
but boy, do I still have a lot to learn about your product and JR's macros.

[James Ritson]

Hey @RTSullins, I came here to copy-paste my reply on Reddit but you've already found it! Glad to hear using File>New Stack works for you.

For the benefit of anyone else with a similar issue, here's the reply I wrote:

Quote

You're opening an 8-bit compressed JPEG into a workspace that's primarily designed to work with high quality linear RAW data (e.g. out of camera RAW files or FIT files). There is a gamma transform (Levels adjustment) and tone shaper (Curves adjustment) being added non-destructively on top of the images you're previewing—this will be why your JPEG looks posterised and has banding, it simply doesn't have the precision and fidelity for this kind of workflow. Also, this workspace aligns by star detail, so you probably would have found your sun images failing to align I think.

If you want to stack multiple images of an object using gamma-encoded and compressed files (e.g. out of camera JPEGs), try File>New Stack instead. This will align and load the images into a live stack group which defaults to a Median operator. Try switching it to Mean for better noise rejection.

Hope that helps!

 

[Shaunik]

@RTSullinsdid you get any luck with the FITS files. I just brought Vespera II and purchased license for AP. I think inability to get these other files dark frames, light frames etc. will be the biggest challenge with Vespera II and AP. Do we really need them @James Ritson, I think Vaonis team have system in place to process these files already. I should have done more research before getting the AP license.