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 everyone
Is it correct to use bias frames,not dark frames to calibrate FLAT frames?
I can't have dark frames with the same exposure time as a FLAT frames, so I would like to use a bias frames.
thank you.
Yes, you need either bias or darkflats to calibrate the flats. Why is it that you can't expose as long as a flat?
@vincent-modÂ
I use a telescope subscription service, which doesn't offer the same dark exposure time as flat.
That's why I want to use a bias that doesn't matter the exposure time.
I understand that dark is the most suitable for removing noise related to exposure time, but I think that flat can use bias as a second best measure because of its short exposure time.
Is my understanding of this correct?
Thanks
Yes, flats can use the bias as well, they should have the same gain/offset settings though.
@mo-mo If you use darks and bias then APP can scale the darks to match the exposure times of the flats so the flats can be calibrated. The bias and darks then, as @vincent-mod also indicated, need to have the same gain, offset and temperature as the flats.Â
Thank you Wouter
To calibrate flat, can I get better results that use bias and dark than using only bias?
As a premise, use the appropriate bias, dark.
@mo-mo In case of flats, there is not much difference between using bias only and using bias and darks. The reason is that flats contain so much signal that both bias and dark contribute very little to the raw subs.
I will use the bias frame for calibration in the future.
Having less exposure time for the bias frame than for the dark frame is very important for shooting in a limited amount of time.
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Thank you
