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 shoot with an OSC and I want to create Hubble palette images.Â
I understand that I first need to extract the OIII, Ha and SII channels from my colour image and then re-combine them.
I can extract Ha and OIII in APP, but there seems to be no option to extract SII. Is this correct? If so, when you you plan to add that? It seems odd to leave one of the channels out.
Thanks
SII will be mixed into the spectrum of the Ha and OIII if you used a dualband-filter. If you specifically want SII, you need a filter for that. Software can't distinguish specific wavelengths. And when you have the SII data, you can select SII in the algorithm. The extract options are meant for dualband filters.
Thanks Vincent. Sorry I am new to all this!
If software cannot distinguish different wavelengths, then how can it do this for Ha and OIII from a colour image?Â
I am using a optolong L-extreme filter. Does this mean I can only extract Ha and OIII in APP?
If so, how can I make a Hubble palette image?
Thank you 🙂
No problem, this is quite a tricky thing sometimes. For a dual channel filter, most of the Ha will be captured in the red channel and OIII in the green/blue channel. APP can nicely and with retaining the original resolution, separate those channels automatically. But that's all it can do, the signal lands on your sensor and is filtered by the bayer-matrix to red, green and blue. This is all APP can see and it can't distinguish between signals within that. To be able to really get the signals you want, you need filters that you know will only let through e.g. SII. The L-extreme is a dual-band filter and indeed can only separate Ha and OIII, for SII you'd need a SII filter. Ideally, a mono sensor with filters for OIII, Ha and SII are used.
No problem, this is quite a tricky thing sometimes. For a dual channel filter, most of the Ha will be captured in the red channel and OIII in the green/blue channel. APP can nicely and with retaining the original resolution, separate those channels automatically. But that's all it can do, the signal lands on your sensor and is filtered by the bayer-matrix to red, green and blue. This is all APP can see and it can't distinguish between signals within that. To be able to really get the signals you want, you need filters that you know will only let through e.g. SII. The L-extreme is a dual-band filter and indeed can only separate Ha and OIII, for SII you'd need a SII filter. Ideally, a mono sensor with filters for OIII, Ha and SII are used.
Ah, yes. Of course. APP can separate OIII and Ha because they mostly fall in B and R pixels. But because the SII emission is also red it gets mixed with the Ha and so APP has no way to separate it. This makes sense.
So I am thinking that if I shoot with OSC and l-extreme then use APP to generate the OIII and Ha channels, I then shoot again using a SII filter. Then I have all three channels and can combine them to make a Hubble palette image.
I guess the only problem is that SII is weak and the Bayer matrix will reduce this still further. So I would need a LOT of subs!
Long exposures mainly, more so than many subs in the case of narrowband. The more the better, but per sub you also want as much signal as possible. 15 min exposures are actually used quite often. This is where mono sensors indeed can have an advantage, as the entire sensor can be used to collect signal. Though modern color sensors are quite good as well.
