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Gradient Removal

Posted: Sat Jan 06, 2018 12:05 am
by pjwack
I have been using AstroLive. One nice feature is the gradient removal for removing a lot
of skyglow, moonlight, etc. Just started using Sharpcap and have not come across a comparable feature..although
that could well be due to my inexperience with the program. Thoughts?

Re: Gradient Removal

Posted: Sat Jan 06, 2018 4:50 pm
by admin
Hi,

currently there is no feature to do this in SharpCap. I try to keep the amount of image processing available in SharpCap to a minimum, because there are so many great programs already that do image processing like AstroArt, PixInsight, etc - I can't hope to compete with those programs and also develop SharpCap in interesting ways as an image capturing application.

The one area where there is more image processing is of course Live Stacking, where automatic gradient removal might be an interesting addition. I will keep the idea in mind for a future version.

cheers,

Robin

Re: Gradient Removal

Posted: Mon Jan 08, 2018 1:17 am
by Bikerdib
I as well as lots of others (from what I've read on various forums) use Sharpcap for EAA aka NRTV. That could be a useful addition to live stacking.

Re: Gradient Removal

Posted: Wed Jan 10, 2018 12:57 am
by pjwack
yes- i was referring to it's use for live stacking, where the use case is more about immediate gratification as opposed
to heavy post-processing:)). You can definitely use a UV filters and/or move the blackpoint, but I've found the astrolive gradient removal
to be a quick way to get 90% of the way there. thanks.

Re: Gradient Removal

Posted: Mon Feb 19, 2018 2:48 am
by nm1213
Also, I live stack with an alt-az mount, and the gradient artifacts increase over time around the edges due to field rotation. I wonder if removing gradients from each exposure before stacking will help minimise the amount of field rotation gradient artifacting that chews into usable image size?

Re: Gradient Removal

Posted: Fri May 18, 2018 1:33 am
by galljj
Robin:

I thought you might be interested in knowing of a post that was made today over on Cloudy Nights, by Kyle Goodwin

He says:

As the developer of AstroLive USB I can say that SharpCap is the way to go. I stopped developing and selling AstroLive USB two years ago, so it's quite out of date now. It does have a few advanced features that nothing else has for live gradient removal and curves control, but I think this is totally outweighed by the much better aligned stacking, autofocus, plate solving, device compatibility, etc. now present in SharpCap. I've been considering making AstroLive USB open source so others can work on it, but there hasn't yet been enough interest from anyone who has the skills to work on it to justify the time it would take to clean up to release that way. I'm interested in the SharpCap plugin functionality since some of the unique processing features in AstroLive USB could probably be reimplemented as SharpCap python plugins. If anyone is interested in doing something like that I'd definitely be willing to give you access to the source so that you could do the port.

Re: Gradient Removal

Posted: Fri May 18, 2018 5:50 am
by admin
Wow, that is interesting - thanks for bringing it to my attention.

Robin

Re: Gradient Removal

Posted: Tue Jul 02, 2019 10:10 pm
by bennyc
+1

Something like a lightweight version of PixInsights AutomaticBackgroundExtraction would tremendously improve the live stacking view - in my Bortle 7 skies there's frequently a gradient hiding the things I want to see and throwing off the automatic histogram features. When taking the stack into PI later the ABE reveals much more in the image, but I would like to see that live :-)

Histogram controls can help when the background is somewhat even, but often LP presents as a 2D gradient and that needs to be subtracted, you can't get rid of that with the histogram.

Re: Gradient Removal

Posted: Wed Jul 03, 2019 9:03 pm
by admin
Hi,

If anyone has examples of images both before and after this type of gradient removal and could share links here (perhaps to images on astrobin or in dropbox/OneDrive) then those images would provide some useful test cases for me when thinking about how to implement an algorithm to perform this function. I don't think that this feature will make it to the next major release of SharpCap, but it is a nice feature that I would like to implement at some point in the future.

Cheers, Robin

Re: Gradient Removal

Posted: Thu Jul 04, 2019 8:57 pm
by bennyc
Hello, Robin, I sent you a PM with a pair of files - PM or email me if there's any other files you would like.