30 July 2020 - APP 1.083-beta1 has been released introducing Comet processing! This 1st beta has comet registration. The stable release will also include special comet integration modes.
9 July 2020 - New and updated video tutorial using APP 1.081: Complete LRGB Tutorial of NGC292, The Small Magellanic Cloud by Christian Sasse (iTelescope.net) and Mabula Haverkamp
2019 September: Astro Pixel Processor and iTelescope.net celebrate a new Partnership!
APP eating up colors?
I really like APP. Currently use APP 1.083-beta1.
Still, I often use other applications to stack - DSS, SiriL and Sequator just to see if there's a difference.
Sequator I use often for wide-field with a background which needs to be "frozen".
So, I got some wide-field pictures of Milky Way and stacked those in APP, DSS and Sequator.
APP stack is clearly lacking color comparing to DSS and Sequator.
Also the hills should be brownish as in DSS and Sequator but they are green (as if it was spring-time) in APP.
I wonder why?
Could you mention what you tried to use in APP? Like your workflow?
Everything was default. Integration - auto. Stretch 15% BG, 3 sigma, 2.5% base, save as tiff and finish in Photoshop like others (setting up the black level and nothing else).
Right ok, so what you see here is more the raw data then. In APP you can use the LP (light pollution tool) to remove some more gradients and the star color correction to get the best colors. Then on the right you can switch on saturation and it should look a lot better already.
It was about a month ago when I collected/processed this set of data... I don't remember exactly what I did to every stack.
So I went ahead and restacked/reprocessed. And got completely different result with APP!
Now APP is very close to Sequator and DSS.
Can this be 1.082 (which I used a month ago) vs 1.083b1 (which I used today)?
Here's what I did.
Stacked with APP, Sequator and DSS.
Processed each stack in APP:
-- calibrated background (5 boxes - four in the corners and one close to the middle, avoiding the ground).
-- calibrated star colors (one big box excluding the ground/hills).
-- 15% BG, 3 sigma, 2.5 base. Save to 16b TIFF.
-- Photoshop. Adjust black level, resize and save to jpeg.
All three did similarly and well.
DSS was OK but didn't stack stars properly in the right-top corner.
Sequator worked surprisingly well. It doesn't work as good for high-magnification DSO but for wide-field it's really good.
APP did very well. Not sure what happened the previous attempt. Maybe there was really something in 1.082.
And, by the way, that was unmodified Nikon D5500 with 14mm lens (ISO6400 and f/4) at Bortle 4 location. Just 10x13s frames.
Mmm, not sure if that much changed between those versions (I would have to check the release info for that), but at least it works now to your liking which is what matters. 🙂 You're sure you did the same star color calibration in the first try?