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jonnydreads

Processing my image in gimp (very dark)

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Hi all.

Any tips on how to pull my image though using gimp? I have the pinwheel galaxy but it's completely black apart from the odd star... it looked brighter in dss.

I know the data is kind of there because when I use the auto tools such as auto white balance or auto desaturate I can quite clearly see the galaxy but it looks crap.

I have messed about a bit using techniques from various books but to no avail without using the auto tools it's virtually non existant.

Thanks Jon 

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Hi Jon, I personally don't use Gimp. I know there are many tutorials on using Gimp on YouTube. GIMP and you will have ample tutorials to gain your knowledge :)

Steve

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Although some won't recommend doing things this way, when you 'Save picture to a file' in DSS, tick 'Apply adjustments to the saved image'. That will save the image with any brightness/colour changes you made in DSS, making the DSS view closer to what GIMP will show.

Also, ensure GIMP is at least version 2.10 for 32 bit image support.

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I will try that....... there are lots of people on here that recommend what NOT to do... ? ok ye I'll keep at it. Cheers 

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Hi Jon, as bobro pointed out, ensure you have the lastest version of Gimp installed 2.10.8 for 16/32bit support but I'm assuming you have tried adjusting the Colours > Levels within Gimp for the Black point and Midtone sliders.

You should see a histogram spike in there and by sliding the Midpoint slider to the left slightly should brighten the image but use fine adjustments. Make sure the "Preview" box is ticked also so you can see the adjustments on the image as you adjust the sliders.

image.png.133c79fda89dd93315f618f54b1b450d.png

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I messed around for ages, the only way I could see anything resembling an image was messing about with saturation and hue levels, the image was almost black when it came into gimp....the problem is I'm left with this orange glow and if I try to get rid of it the image virtually loses all data....... to be fair they are only 15 second subs and I'm using an alt/az mount with no guiding... it's in the north sky so I have had to delete lots of star trailed subs...... maybe it would easier if I can ever get round to finishing my wedge... ?

pinwheel2.jpeg

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You have done very well producing this image with only 15 second subs - well done! M101 isn't an easy target - not the brightest.

Of course a wedge and longer exposure will help. Messier 81 at this time of year?

 

 

 

 

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9 hours ago, bobro said:

You have done very well producing this image with only 15 second subs - well done! M101 isn't an easy target - not the brightest.

Of course a wedge and longer exposure will help. Messier 81 at this time of year?

 

 

 

 

Thanks, I didn't realise it wasn't an easy target..... I was just very brutal when it came to throwing out poor quality subs,  and there was a lot of them ?

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