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.
Thank you Stratos for sharing your data with us 😉 I have had a go myself since I am actually working to improve HaRGB and LHaRGB composites for a future APP release.
The workflow to do star color calibration on a HaRGB (or a LHaRGB) is not recommended, in fact it is physically a wrong step. You need to do star color calibration on broadband data. If you add narrowband data in the mix and then try to perform star color calibration on a broadband+narrowband composite, it would be mere coincidence if the colors look good...
Star color calibration needs broadband data to make sense of the star color physics. Adding narrowband data in there will cause the R/G B/G ratio's of the stars in your data to be polluted by the narrowband emissions. Those narroband emissions don't follow the physics at all that we use for star color calibration.
So how to do this properly then?
1) create a RGB (or LRGB compositie), in this case I used formula RGB 2 in the RGB Combine tool
2) perform Remove Light Pollution and Background Calibration on the RGB composite ( ! if you perform Remove Light Pollution, you automatically perform Background Calibration, there is no need to do it again after Remove Light Pollution)
3) Perform Star Color Calibration on this RGB composite that is corrected for light pollution and is background calibrated:
4) We know open the RGB Combine tool and will add the H-alpha layer. Now, this next 2 steps are essential to preserve the RGB Star Color Calibrated colors in your composite:
set normalize to none in the RGB Combine tool.
Load the RGB star color calibrated result into the tool with the RGB 1 formula
These 2 steps will preserve the colors of the star color calibration 🙂 !
5) Add the H-alpha layer in the RGB Combine tool.
6) To preserve the colors and luminance of your star color calibrated result, set the luminance for the composite so that it is preserved. Normally you want Red to contribute for roughly 20%, Green for 70% and Blue for 10%.
7) And slightly add H-alpha to red, I added it for 23% to Red as can be seen in the below screenshot. Now to maintain the star colors, you need to gently adjust the multipliers for the R,G,B channels as can be seen as well. Red 1,15, Green 1,17, Blue 1,20. These factors do depend on the data, you need to do this carefully. Try to get the same colors as the star color calibrated result off course 😉
I am working to make this more automatic and easier for the user off course, but this is a proper workflow in which you can get good star colors with narrowband included to enhance the active regions in this case of M51 😉
This show the star color calibration result next to the final HaRGB composite: we see that star colors are still good and we also see much more enhanced active regions in M51 from the H-alpha data, top is the RGB composite after star color calibration, below is the finals HaRGB composite with the same star colors 🙂 :
Let me know if this is clear and/or if you have any questions about this workflow 😉
Crop of the field of view of the final HaRGB:
Cheers,
Mabula
This post was modified 6 years ago by Mabula-Admin
Owkee, well, I'm learning something as well there. 😉 I was assuming that, since there is broadband data, it would still work. But makes sense indeed, that's why I needed to fiddle around with the slopes apparently.
First of all I must thank you for this great explained workflow and saw us where was our mistake ...
This is great because we know now to process narrowband and broadband data ... The last years color cameras with narrowband and broadband filters are so popular and seems like the came to stay ...
This will be great tutorial for all people that use this kind of equipment...
I will try it this tutorial and I let you know how went ...
ps you can upload your version in server that can I take it to compare with mine ?
