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.
When the skies clear(!), I shoot mostly nebulas, with a modified Nikon D5300 and an L-Extreme filter. This gives me Ha + OIII. But my OIII is always weaker and noisier than my Ha, and I have no SII available.
So... I'm thinking of acquiring an IDAS NB3 filter, which (combined with the L-Extreme's data) will give me additional OIII signal, plus some SII.
What I'd like to understand is how best to split out the SII.
I expect that I'd just use Ha-OIII-Extract-OIII for the NB3 filter's OIII side. (correct?)
But for the SII... should I just pretend that it's Ha and use Extract-Ha for SII, or should use the (only)SII selection, or something else entirely? I don't really understand what's going on internally (bayer-wise) with these choices.
Thanks for your help with this!
@devonshire Hi!
Since both Ha and SII are Red, it will be impossible to split them. You'll need a filter that only has SII in the red part of the spectrum for this.
Wouter
Wouter,
Thanks for the response. Separating Ha and SII wasn't the question - they would not be be mixed in the lights. The L-Extreme gives me red Ha data. The NB3 would give me red SII data, because it blocks Ha.
The question was how best to extract the SII red from the NB3's data.
Yes, the question down the road will be how best to assemble it all, but for now, I'm just trying to put a box around the SII extraction.
@devonshire Sorry, I misinterpreted the filter pass diagram and thought that both Ha  and SII were passed through. But you are right of course that it doesn't.
In that case you can use the extract Ha algorithm because the lights will be (undebayered) RGB files. The SII option is for mono lights.. Just keep in mind that APP will name the file incorrectly (which can easily be remedied outside of APP) but also the filter tag in the FITS header. Just make sure to select SII when you load the file in the Combine RGB Tool.
Ok - thanks! Yes, that's fine.
