Improvements to lig...
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Improvements to light pollution removal  


White Dwarf Customer
Joined: 3 years ago
Posts: 20
January 31, 2019 02:55  

I find that APP has the absolute best light pollution removal system out there. I'm extremely happy with the results.

My only issue is it's extremely tedious to use at times. For very nebulous images it's quite simple, hand draw a few boxes in areas of no nebulosity.  However, in galaxy or cluster images where the background is mostly black, it becomes tedious. I find the algorithm does best when drawing small boxes tightly packed together, it's able to correct out subtle issues that are not removed when drawing large boxes. 

What I think would improve this process is an "auto-grid". A small interface option that will pre-draw a grid of boxes to your specified sizes, like a grid 25x25 boxes, or 10x10, etc. From there, you would need to be able to select and remove the boxes that interfere with objects in the main viewer. So in effect the opposite of what I do now, which is to manually draw possibly hundreds of boxes everywhere except where objects are. You would auto grid the boxes on the entire image, then just deselect or remove the boxes that interfere with objects in your images.

Neutron Star Customer
Joined: 2 years ago
Posts: 177
January 31, 2019 08:51  

I second this request. Some panel that shows a selected box with its immediate surroundings so it can be inspected and moved or deleted if necessary would be great as well.


Main Sequence Star Customer
Joined: 9 months ago
Posts: 35
September 4, 2019 10:36  

Instead, or better, along with the tedious rectangles, why not have something similar to the iris gradient removal workflow?

Basically, you set a threshold for luminosity, and a mask is generated, which in APP could be in a form of many small rectangles. You adjust the threshold until the interesting object (e.g. nebula or galaxy) are not in the mask, and use that map as the input to generating the gradient for removal.

I would love to be able to start with this workflow, then perhaps add some rectangles of my own and call it the day!

See Iris tutorial on the subject (section titles "Automatic procedure"). Also here is a video of the process


It is rather tedious in Iris, but I am sure APP could utilize the concept and make it much better and more intuitive.

This post was modified 9 months ago by Shlomi Vaknin