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's the meaning of kappa low and high for winsorized averaging? My understanding of winsorized averaging would be that one provides a percentile (maybe upper and lower) at which to clip and replace the clipped values with these percentiles.
I assume that kappa is usually the standard deviation of a list of values in APP?
Thanks in advance!
Björn
Hi Björn @barnold84,
Kappa is the number of times the scale/dispersion factor is applied for rejection. Scale/dispersion is usually the standard deviaton. APP uses a weighted standard deviation since you integrate with weights.
Kappa low, is the kappa that is applied for rejection on all pixels in the pixel stack that are below the central value. The central value is usually the average or median of the pixel stack.
Kappa high then is the kappa that is applied for rejection on all pixels in the pixel stack that are higher than that central value.
The reason to discriminate between the two sides relative to the central value is is that the pixel value distribution usually is not symmetric and that most rejection usually needs to be done on pixels with too high values, like hot pixels for instance.
Winsorization is replacing all pixels values that are higher and lower than a fixed threshold by their threshold to get a winsorized central value and scale/dispersion. The rejection kappa's are then applied to the pixel stack using the winsorized central value and scale/dispersion value.
Let me know if this answers your question or if you have any others,
Mabula
