GRADIENTS!!

[TheMan]

I use a dslr and a 72 ed f/5.5 refractor, I use photoshop cc 2017, i live in bortle class 8 close to 9 skies, yet it does no matter how many tutorials i watch i cannot remove these pesky GRADIENTS! I tried everything in the and yet i cannot remove the gradients. i tried doug germans tutorial, astrobackards tutorial and many others. i am saving for a field flattener and cannot buy astronomy tools for photoshop. any advice will be appreciated.

[RolandKol]

Have you tried "PixInsight LE", the Old and Free Pixinsight version? It has quite a powerful gradient removal tool.

[tooth_dr]

That’s a nice image. First thing I would do would be take flats. Once applied they won’t remove the big gradient but they will remove some optically-induced gradients and dust bunnies and make processing overall much easier. 

[tooth_dr]

Here is the original and my effort

[Ouroboros]

@tooth_dr is that with PixInsight? 

@TheMan that's a petty good image for Bortle Class 8/9.  The colours are nice. Did you have to struggle to get the colour balance right against the colour cast provided by so much light pollution? That's been my problem when imaging under such conditions. 

I agree with the earlier comment that flats would help this image. Though of course it's recommended to take the flats at the time, you might just for the exercise try taking some flats even now and applying them. You might be lucky and it helps if dust bunnies haven't moved. Assuming you've disassembled your set up you'll have to put things back as close as possible to where they were when you took the data, including having the camera at focus. I've done this on occassion and been pleasantly surprised how well it works. 

Edited November 11, 2018 by Ouroboros

[tooth_dr]

14 minutes ago, Ouroboros said:

@tooth_dr is that with PixInsight? 

@TheMan that's a petty good image for Bortle Class 8/9.  The colours are nice. Did you have to struggle to get the colour balance right against the colour cast provided by so much light pollution? That's been my problem when imaging under such conditions. 

I agree with the earlier comment that flats would help this image. Though of course it's recommended to take the flats at the time, you might just for the exercise try taking some flats even now and applying them. You might be lucky and it helps if dust bunnies haven't moved. Assuming you've disassembled your set up you'll have to put things back as close as possible to where they were when you took the data, including having the camera at focus. I've done this on occassion and been pleasantly surprised how well it works. 

PS - Gradient Xterminator, and then adjusted levels to get black point a little lower, and star size reduction, and some noise reduction..

[martin_h]

My effort using Dradient XTerminator plug-in for Photoshop.

 

[TheMan]

These are some nice gradient removal. but GXT is paid and pixinsight LE is illegal to get, if you read the legal notes on it. 

[wimvb]

+1 for taking flats. Even if you can remove the gradients, you're still left with those dark spots. It's always best to calibrate out artefacts than it is to reduce them during post processing. Most dust bunnies originate from dust specs near the camera window. With luck you may be able to get rid of them with new flats, as @Ouroboros noted. Any remaining gradients can then be reduced with either DBE in PixInsight or Gradient Exterminator.

PixInsight (on your jpeg, which I wouldn't normally do):

• DBE x 2
• Background neutralised
• HDR transformation at 50%
• Cleaned up some of the dark rings around the smaller stars
• Tweaked contrast and saturation, reducing the dust bunnies (this also reduced the faint nebulosity a bit)

[wornish]

Here is an excellent tutorial in removing gradients using Photoshop and its basic tools.  The steps are to create a synthetic flat and then subtract the flat from your image.

You can fix your gradients for FREE.

 

 

 

Edited November 11, 2018 by wornish

[happy-kat]

Why not try the free trail of StarTools, it is a fully working version just can't save so do a screen grab while trailing it. The cost of StarTools will bring many great tools plus an excellent gradient remover and it is about the same cost of just gradient exterminator plugin for photoshop.

Edited November 11, 2018 by happy-kat

[john2y]

6 hours ago, happy-kat said:

Why not try the free trail of StarTools, it is a fully working version just can't save so do a screen grab while trailing it. The cost of StarTools will bring many great tools plus an excellent gradient remover and it is about the same cost of just gradient exterminator plugin for photoshop.

 

It looks like the gradient removal process clipped the background completely so it's just black. Also some nebulosity got clipped as well.

[happy-kat]

It's not clippee but I agree it is too close than ideal. If I stretch it to bring out the nebulously the dust bunnies show. Ideally you'd process fresh from the stack using the autosave fits file rather than process a jpeg. Flats would help the large dust bunnies.

Edited November 11, 2018 by happy-kat

[Nicola Hannah Butterfield]

Just worked through the above tutorial. Tight crop from a full frame DSLR

[Chefgage]

On 11/11/2018 at 05:45, TheMan said:

I use a dslr and a 72 ed f/5.5 refractor, I use photoshop cc 2017, i live in bortle class 8 close to 9 skies, yet it does no matter how many tutorials i watch i cannot remove these pesky GRADIENTS! I tried everything in the and yet i cannot remove the gradients. i tried doug germans tutorial, astrobackards tutorial and many others. i am saving for a field flattener and cannot buy astronomy tools for photoshop. any advice will be appreciated.

I have just done some gradient removal on the same target. I use GIMP to process and used the despeckle tool to remove the gradient. Worked quite well. This is the image, ignore the first image in the post.

 

[Tayson]

For gradients AstroPixelProcessor.