2026-10-09 APP 2.0.0-beta48 has been released !
This is mainly a bug fix release for the reported bugs in beta47. In addition it has a significant User Interface performance improvement noticable when you need to process 1000s of images in APP.
2026-10-03 APP 2.0.0-beta47 has been released !
This is a very big release... many code optimizations/rewrites, many parts of APP are much faster and more precise, especially star analysis and registration are much faster ! Big mosaics will go much faster 🙂
And we introduce a new preview filter, which includes the new Adaptive Deep Sky Stretch and a General Levels Stretch, this has been long over due. The old preview filter (the panel on the right side to stretch and preview your data) has not been updated for a couple of years and it is a critical part of any APP session.
Adaptive Deep Sky Stretch or ADSS is a much more intuitive stretch algorithm. It is also color preserving (which is a great new addition in itself ! ) which means that the highlights are no longer bleached, color is maintained from the linear data while stretching. You can simply stretch your data using the sky background level and signal width sliders which work much easier and more intuitive. You no longer need to fiddle with the old complicated sliders with zoom buttons. All the zoom buttons for the sliders are made redundant. And you can enter slider values in the slider value fields yourself. I will make a youtube video in the coming days to explain and fully introduce ADSS. Once the video is ready, it will be highlighted on the forum.
RGB Combine upgrade !. The RGB Combine Tool has been rewritten mostly. The tool is faster and easier to use and most importantly, the Luminance slider to inject a luminance channel or channels into the RGB composite is now working correctly. It no longer bleaches the RGB colors. Combined with the new ADSS preview, you will get much better and easier great composites with great color! I will also explain this in a new youtube video.
I've taken two nights of 180-degree fisheye images, one night with H alpha filter, the other with O III. The pointing was adjusted each hour, and 60 exposures of 1 minute each were made, while tracking on the fixed pointing.
The 60 exposures with the same pointing stack nicely, but I can't manage to register the stacks with the different pointing. Distortion is of course extreme with a fisheye lens, which is probably where the problem lies.
Any tips on how to tackle this?
Mmm, tricky one, I've not seen fisheye stacking yet here. What does APP say exactly when you try to stack those? Or what does it look like? I can imagine that the distortion that changes with different pointing might make it very difficult to align them.
It either can't register at all, no matching star pairs found, or gives a bad registration value, typically several tens of pixels RMS, with areas that register OK-ish and other areas that are clearly way off.
The image above is a lucky one where both colours happened to be close enough in pointing to give nice registration. Some others I tried look pretty bad if they register at all.
I tried various amounts of stars, pattern recognitions, distortion correction, and registration model. I haven't played around yet with distortion margin.
I was hoping that the Calibrated Projective registration model would be able to deal with the distortion but that didn't work (yet). It probably needs to know more about the distortion in the lens, whether it's F * tan(theta) or F * theta projection or something else. The lens I used is https://www.sigmaphoto.com/8mm-f35-ex-dg-circular-fisheye
If needed I can upload some of the stacks.
Let me ask Mabula first if it's even a possibility. I might then ask for the data, always interesting if we can implement something that might work with it.
I asked Mabula and this is indeed not really possible. Especially as the view changes, making the distortion very different.
OK, thanks for checking. I'll put my hopes on the "not really possible" as opposed to "not possible" and hope for a (more distant) future update. 😉
That's always a good thing, having a positive mindset. haha The problem with fisheye lenses is that distortion, it's very variable and is likely not possible because it would need to distort the image to be able to align them. It wouldn't look good. Keeping the same point direction might still kind of work like you already noticed.
