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.
Hello!
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I got a question regarding the drizzle.
I wanted to use it for images I took with my 300mm refractor, which leads to quite some undersampling.
However, I am not entirely sure how to understand the settings.
The example given is that droplet size of 0.5 and scale of 2 is the same as 2x drizzling.
But what would happen with 0.5 droplet size and scale 1? It will not add more pixels, so nothing should happen, right?
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Is it recommended to adapt the scaling based on the droplet size as well? For example, 0.75 droplet + 1.5 scaling, or is the same scaling alright with any droplet size?
What happens with a droplet size > 1? Will that decrease the resolution?
Sorry for the many questions, I am a bit confused on how I should adapt the settings properly.
Thank you!
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CS Tobi
Hi Tobi @tobigh3,
Thank you very much for your question.
The example given is that droplet size of 0.5 and scale of 2 is the same as 2x drizzling.
Indeed, that is what commonly is called 2x drizzling.
3x drizzle would be scale 3.0 and droplets even smaller like 0,33
But I think you better look at it differently and realize that there are 3 factors to adjust to perform drizzle and get different results. Beside scale and droplet, the drizzle kernel will also affect results.
The first and most essential thing about drizzle is that it is a noise injector and this is directly controlled with the droplet size for a given scale and kernel. Lower droplets give more nosie and possible more sharpness and vice versa. So the best droplet setting is dependent on how much sharpness you want to achieve and how much noise you can live with 🙂
I would recommend that you simply use scale = 2.0x and vary the droplet size between 1.0 and 0.5, experiment a bit to see what the differences are.
For Bayer/X-trans Drizzle, simply use 2x the droplet size as compared to drizzle on monochrome data. So with OSC/color data and Bayer/X-trans drizzle, droplets of 2.0 equal droplets of 1.0 (we need to fill the CFA holes).
Also, if you keep scale 1.0 but use droplets lower than 1.0, you might not fully see the sharpness increase because there are not more pixels to show it, and the smaller droplets do inject more noise. So better the other way round. Increase scale to 2.0x and then lower the droplets step by step until you get a good balance of sharpness and noise.
Use the Crop composition mode in 6) Integrate to only integrate a small part of your field of view for testing and getting the correct values for drizzle. When you get good parameters change the compostion mode to full again and make your integration 🙂
Oh once you have found nice parameters, do test what happens with a different drizzle kernel, you will probably see different results on you star borders...
Please let me know if this explains it a bit more.
Mabula
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Hi Mabula,
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That clears up a lot, thank you for the detailled explanation! 🙂
Which one is the recommended kernel for drizzling? I didn't change anything there as I thought the default one will be the best.
Also, from what I understand, bayer drizzle is generally better than regular drizzle, is that correct? Or are there situations where regular drizzle has an advantage?
Thank you!
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Best regards
Tobi
Which one is the recommended kernel for drizzling? I didn't change anything there as I thought the default one will be the best.
In my experience with using APP the default settings seem to be the "best" settings in most situations. But it depends on your data.
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Also, from what I understand, bayer drizzle is generally better than regular drizzle, is that correct? Or are there situations where regular drizzle has an advantage?
drizzle => monochrome data
bayer drizzle => osc/color data
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Alright, thank you!
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One more question just came up:
If I want to combine for example RGB + Ha + Oiii, should all of those be integrated on the same drizzle settings? For example, since Oiii is usually noisier, I could decide to not drizzle there, but drizzle my Ha. Will this become a problem when combining them in Photoshop for example?
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Alright, thank you!
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One more question just came up:
If I want to combine for example RGB + Ha + Oiii, should all of those be integrated on the same drizzle settings? For example, since Oiii is usually noisier, I could decide to not drizzle there, but drizzle my Ha. Will this become a problem when combining them in Photoshop for example?
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This should not be a problem. But if you drizzle with too low droplet size, the stars could have clear drizzle artefacts, then it can become a problem which you can solve by using higher droplet sizes 😉
Mabula
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