Gradient Removal

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'+1' posts are welcome in this area of the forums to indicate your support for a particular feature suggestion. Suggestions that get the most +1's will be seriously considered for inclusion in future versions of SharpCap.
pjwack
Posts: 24
Joined: Fri Jan 05, 2018 11:52 pm

Gradient Removal

#1

Post 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?
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admin
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Re: Gradient Removal

#2

Post 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
Bikerdib
Posts: 19
Joined: Tue Dec 19, 2017 3:21 am

Re: Gradient Removal

#3

Post 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.
pjwack
Posts: 24
Joined: Fri Jan 05, 2018 11:52 pm

Re: Gradient Removal

#4

Post 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.
nm1213
Posts: 33
Joined: Mon Feb 19, 2018 1:47 am

Re: Gradient Removal

#5

Post 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?
galljj
Posts: 80
Joined: Wed Mar 01, 2017 10:14 pm

Re: Gradient Removal

#6

Post 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.
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admin
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Re: Gradient Removal

#7

Post by admin »

Wow, that is interesting - thanks for bringing it to my attention.

Robin
bennyc
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Joined: Tue Jul 02, 2019 9:52 pm

Re: Gradient Removal

#8

Post 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.
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admin
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Re: Gradient Removal

#9

Post 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
bennyc
Posts: 2
Joined: Tue Jul 02, 2019 9:52 pm

Re: Gradient Removal

#10

Post 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.
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