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,
What size and frequency of dithering between exposures would you advice to achieve effective noise reduction?
I have been analysing the SNR improvement as I stack increasing number of images in APP and I suspect it's not as good as it could be (ie significantly less than the squareroot improvement that I would expect using a limited read noise camera).
I also suspect that I could improve SNR with a more effective dither, hence my question. Typically I have been using a relatively small dither (3-5 px) every 5th exposure or so. The question is how much of a change should I aim for? Would noise reduction improve with a larger dither of say 15-20 px and would it be beneficial to dither after every exposure?
Before heading into trial&error mode, some guidance on the way would be very much appreciated 😊
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Thanks,
Anders
You can check out this reply from Wouter: https://www.astropixelprocessor.com/community/tutorials-workflows/compute-the-amount-of-pixels-to-dither/#post-26700
And the effect of dithering will reduce fixed noise patterns, not the random noise. Random noise lowers with more data, but will always be there. Given the answer from Wouter above, we usually dither for 10 pixels even or more.
Thanks for the quick reply. Very useful information.
What is not explicitly stated is if it is meaningful, from the noise reduction perspective, to dither after every exposure or if some other frequency will do as well. Especially relevant to know when doing many shorter exposures (like eg  100 frames or more of 120s), dithering after each is, if nothing else, a bit time consuming.
What’s your view?
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Anders
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You're welcome!
The more you dither the better, however I personally do it every 3 frames usually. That will depend on how much data you shoot though, if all you do is 20 frames on 1 object and that's it, I would dither every frame.
