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my phone is better at editing images than I am

Astrophotography
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#1 belliott4488

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Posted 26 February 2021 - 03:40 PM

I have just started out with some basic astrophotography with my DSLR. So far I haven't had the chance to gather multiple images for stacking, calibration frames, or any of that good stuff, so I'm just  trying to learn how to get the most out of single exposures by editing in GIMP.

 

I had been making slow progress when I happened to look at one of my DSLR images on my cell phone, which then offered to apply some preset "enhancements" to my image. Most were ridiculous - think bright green skies - but then I tapped something  called "Luminous" (using Google Photo Editor for Android) and got the result below.

 

Original image:

DSC0006
 
Auto-enhanced by Google Photo Editor for Android ("Luminous" enhancement):
DSC0006 2
 
Ignore the color balance - this enhancement is probably intended for desert scenes or something. What surprised me was how much detail it pulled out of the nebulosity. I had not realized that the detail was even there.
 
This is the best I'd been able to do in GIMP:
DSC0006 (1)

 

So, my question is this: Can anyone tell me what the auto-enhancement did to pull out those details on my phone? Is it a matter of carefully selecting the contrast curve? Black, shadow, and white level points? Most of what I get by trial and error gets ugly fast, so I could use a few pointers.

 

Thanks!



#2 Stelios

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Posted 26 February 2021 - 03:48 PM

I have just started out with some basic astrophotography with my DSLR. So far I haven't had the chance to gather multiple images for stacking, calibration frames, or any of that good stuff, so I'm just  trying to learn how to get the most out of single exposures by editing in GIMP.

 

I had been making slow progress when I happened to look at one of my DSLR images on my cell phone, which then offered to apply some preset "enhancements" to my image. Most were ridiculous - think bright green skies - but then I tapped something  called "Luminous" (using Google Photo Editor for Android) and got the result below.

 

Original image:

 
 
Auto-enhanced by Google Photo Editor for Android ("Luminous" enhancement):
 
 
Ignore the color balance - this enhancement is probably intended for desert scenes or something. What surprised me was how much detail it pulled out of the nebulosity. I had not realized that the detail was even there.
 
This is the best I'd been able to do in GIMP:
 

 

So, my question is this: Can anyone tell me what the auto-enhancement did to pull out those details on my phone? Is it a matter of carefully selecting the contrast curve? Black, shadow, and white level points? Most of what I get by trial and error gets ugly fast, so I could use a few pointers.

 

Thanks!

In your work on GIMP, you've raised the black point too much (darkened the background too much). There's an advice in stretching--"stay gray." That means do not clip highlights or shadows although you can modify intensities. When using curves (best way to stretch) always have the entire curve remain in the box, with no parts sticking to ceiling or floor (which is when data gets clipped). 


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#3 Sam K

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Posted 26 February 2021 - 03:51 PM

Good start...nice pic.  You'll be limited of course, in how much you can enhance any image until you start stacking etc.  There are all sorts of videos online that will walk you through post processing images using all the fun tools out there.  A simple search for "how do I process M42 in GIMP" yielded the following link...among many others.

 

https://www.youtube....b1ceFM-DkQ&t=0s

 

Good luck!


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#4 belliott4488

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Posted 26 February 2021 - 04:18 PM

In your work on GIMP, you've raised the black point too much (darkened the background too much). There's an advice in stretching--"stay gray." That means do not clip highlights or shadows although you can modify intensities. When using curves (best way to stretch) always have the entire curve remain in the box, with no parts sticking to ceiling or floor (which is when data gets clipped). 

Thanks, Stelios! That's exactly the kind of basic tip that I've been looking for. 



#5 belliott4488

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Posted 26 February 2021 - 04:21 PM

Good start...nice pic.  You'll be limited of course, in how much you can enhance any image until you start stacking etc.  There are all sorts of videos online that will walk you through post processing images using all the fun tools out there.  A simple search for "how do I process M42 in GIMP" yielded the following link...among many others.

 

https://www.youtube....b1ceFM-DkQ&t=0s

 

Good luck!

Yes - I'm looking forward to stacking, but this is all so new to me I don't want to get overwhelmed.

 

I'll check Nico's video - I've watched others of his but not this one. The problem I sometimes have with some instructional videos is that they'll say what they're doing and how to do it, but they don't always make it clear why they chose to do what they did. I'm sometimes left wondering, "Well that was great for your image, but does that mean it will apply to mine?"

 

Thanks!



#6 Stelios

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Posted 26 February 2021 - 05:03 PM

If you can afford this book, it will be the best money you'll spend on the hobby. Covers principles, acquisition and processing with both Photoshop and Pixinsight. Photoshop principles should translate to GIMP.



#7 belliott4488

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Posted 26 February 2021 - 06:12 PM

If you can afford this book, it will be the best money you'll spend on the hobby. Covers principles, acquisition and processing with both Photoshop and Pixinsight. Photoshop principles should translate to GIMP.

Thanks again, Stelios. Any book that costs less than a good eyepiece is a bargain! ;-)

 

I've been checking different books, on-line tutorials and courses, and so forth, to try to identify the best starting place for me. There are a lot of basics of digital image processing that are still new to me, and I could easily spend months learning just that.

 

This book looks like it will cover what I need, though.




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