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.
Hi,
I'm assuming that, if I do a multi-channel, multi-session stack of Ha and RGB:
- The correct algorithms are assigned to each channel eg Ha to the Ha channel and Airy Disk to the RGB channel?
- The session numbers are separate for each channel eg I can load all my Ha stuff into session 1, 2 etc, and also all my RGB stuff into session 1, 2 etc?
Thanks, Brendan
No, mono and RGB at the same time is not (yet) possible. We also want to change that in a future version. For now it's best to split the RGB data into mono R, G and B and then load those in again together with the Ha mono data. These can then be normalized and stacked together after which the integrations can be loaded into the RGBCombine module.
Thanks. More questions though!
- Is this how to split the RGB channels - https://www.astropixelprocessor.com/community/main-forum/splitting-osc-channels/ ?
- Where is the RGB Combine module?
- What algorithm would I be using to process the R,G,B and Ha frames?
Thanks, Brendan
Is this how to split the RGB channels - https://www.astropixelprocessor.com/community/main-forum/splitting-osc-channels/ /a> ?
Yes. Basically you need to load the RGB integration result as a light and do not load any other files (not lights nor calibration frames). Then go to tab 2 and press "create Masters & assign to Lights". That will basically do nothing. Then enable "split channels" a bit further down in tab 2 and press "SAVE (calibrated) Light frames" and you're done.
Where is the RGB Combine module?
In the Tools tab. It is called "combine RGB".
What algorithm would I be using to process the R,G,B and Ha frames?
In "combine RGB" you can select the HaRGB1 or HaRGB2 formula (not algorithm). Note that when you switch between the two, you need to click the "new formula" button.
Thank you. I would actually be bringing the channels separately into StarTools, not processing in APP (I just use APP for stacking) so I don't know how this would affect your advice. I'll see how I get on.
OK, so I haven't got around to figuring this out yet, but I just realised that I still don't really understand why there's a multi session feature, in which I can load up RGB and H-alpha, when it seems APP won't actually stack RGB and H-alpha? Just while I'm still working on this, what's the answer ie which algorithm will it be using in the RAW/FITS tab if I do this?
why there's a multi session feature
Multi-session processing needs to be used if you want to combine similar data (e.g. RGB only or H-Alpha only) from multiple nights where different calibration files (usually flats) are used. Also if you want to combine similar data (e.g. RGB only or H-Alpha only) from multiple telescopes because those will require different calibration files (in this case flats, darks and dark flats).
which algorithm will it be using in the RAW/FITS tab if I do this?
APP will always use the selected algorithm.
Hi, thanks for this, but I'm still puzzled. Not confused, puzzled, and I'm not really closer to having my question answered!
I have similar RGB and Ha data, with separate flats and associated calibration files.
I want to stack them together using Multi session, which has RGB and Ha options.
From Vincent's first response it sounded like RGB and Ha couldn't be processed together, and that I'd need to split out the RGB.
However, I still don't get, therefore, why multi session has RGB and Ha options, which clearly implies that I can process them together, and I don't need to split out the RGB. Am I right?
Also, given that there are different algorithms for RGB (Airy disk) and Ha, among others, my question is still, which one is used when processing RGB and Ha together?
If it's the one selected, then that would not make sense, because it would be used for processing different types of data using the wrong algorithm, so for example if I select Airy Disk, but I'm stacking RGB and Ha, then that would be incorrectly used for processing the Ha data.
Or (which would ideally be the case), does APP select the correct algorithm for the data, so that the RGB session is processed using the Airy disk algorithm, and the Ha session stacked using the Ha algorithm?
Thanks, Brendan
From Vincent's first response it sounded like RGB and Ha couldn't be processed together, and that I'd need to split out the RGB.
However, I still don't get, therefore, why multi session has RGB and Ha options, which clearly implies that I can process them together, and I don't need to split out the RGB. Am I right?
Yes and no. APP allows for loading the data together but processing them together will lead to errors. Mabula is working on a fix though.
Also, given that there are different algorithms for RGB (Airy disk) and Ha, among others, my question is still, which one is used when processing RGB and Ha together?
Like I said, the one chosen in tab 0 will be used. If you choose "Ha-OIII extract Ha" for instance then that will be used on all data.
If it's the one selected, then that would not make sense, because it would be used for processing different types of data using the wrong algorithm, so for example if I select Airy Disk, but I'm stacking RGB and Ha, then that would be incorrectly used for processing the Ha data.
Correct. This is exactly what APP does which is another reason to not mix data.
Or (which would ideally be the case), does APP select the correct algorithm for the data, so that the RGB session is processed using the Airy disk algorithm, and the Ha session stacked using the Ha algorithm?
It doesn't. Not sure if this is the intended behavior once Mabula has fixed the processing issue mentioned above.
OK, thanks. So, APP has the option to mix data, but I shouldn't mix data - and this is being fixed.
I think I get it now.
Any ideas when it'll be fixed?
@brendan Mabula told me this will be fixed in 1.084, which currently is in the make. It will also allow for mixing "pure" RGB and dual band filter data such that the RGB data get processed into an RGB image and the dual band data into separate Ha and OIII mono images.
OK, sorry, but I still don't get this.
I have two sets of data. One is RGB, the other is Ha.
My objective is to get stacks that I can pull into StarTools, which I use for my post-processing. For this, they need to be exactly registered and the same size. The only way I've found to do this is to use the multi-session option, using RGB and Ha - but apparently I shouldn't do this!
So, I've split the R, G and B out as above, and now I have R, G, B and Ha.
Now, if I don't use Multi-channel, how do I do this?
If I do use Multi-channel, then I'm back to where I started! In which case, generally, what's the story with Multi-channel, in terms of which algorithm to pick? If you're saying we can't mix data, then why have multi-channel at all?
Multi-sessions are there to be able to load in e.g. flats that are session specific together with the data for that session.
If you have your split data (which should be calibrated now) you can load them in as mono data (just set it to the standard settings APP has), you add tags to them (R, G, B, Ha) and then go to the normalize or register tab and "save registered/normalized frames". Then all that data will be registered with each other.
I'm referring to multi-channel, not multi-session.
I understand multi-session, and I thought I understand multi-channel, but I'm not so sure any more!
Anyway, I think I understand what you mean by tagging the data - assigning the data to the channel - so hopefully I can move on with this now.
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Let me know if it indeed works out, otherwise we'll help you for sure!
