Thanks for everyone’s input and interest.
The use of layers is non-destructive, as they have no bearing on the original.
An Adjustment Layer is also non-destructive, plus it has the ability to be infinitely re-editable.
An adjustment layer (in Photoshop or Elements) has a gear icon; clicking this gear icon will re-open the layer and you can change whatever you did; by default, adjustment layers also come pre-equipped with a layer mask.
No. Just no. Your opacity won’t allow you to edit the blur radius afterwards. So that’s not non-destructive retouch. Your argument is mute.
Non-destructive retouch doesn’t create bitmaps layers. It creates settings that can be edited later, these are reversible.
I’m not sure, but maybe layers made by photoflow can be re-edited.
They are non-destructive, so yes, parameters can be changed.
@anon41087856 : Thanks for a better way of explaining. On the real, people who use destructive editing could try non-destructive editors to understand how they work before sounding ignorant.
Pray tell, what is “photoflow”; is it another program entirely or a GIMP add-on/plug-in ?
Let me answer, as I am the main developer of PhotoFlow…
Photoflow is both a standalone application and a GIMP plug-in. In the second case, it allows to open an exiting GIMP layer, apply a number on non-destructive adjustments (what you call adjustment layers), and then send the result back to GIMP. The key point is that the photoflow edit gets saved as meta-data together with the GIMP layer, so if you re-run the plugin on the same layer it will restore all the adjustment layers created previously.
I suggest to read/watch the following links, then I’ll be glad to answer any question and give further explanations:
Which operating system are you using?
Thanks so much!
I am currently using Windows 7 Pro (x64) and very recent GIMP, 2.10.6
I will definitely be exploring PhotoFlow.
You can get the windows version of photoflow here: Release Continuous build · aferrero2707/PhotoFlow · GitHub
Just look at the most recent package having -win64- in its name.
The photoflow plug-in in not currently included in the default GIMP installer for windows, so we need to see how to get it running… however, you can already start familiarising with the standalone application.
The Windows version of photoflow is portable, meaning that you simply need to extract the .zip file anywhere on your hard drive, and run the photoflow.exe executable from the bin sub-folder.
I have already just clicked the green ZIP button here; did that get me the most recent version; it says v0.2.8-2-
http://aferrero2707.github.io/PhotoFlow/
I also downloaded the TAR as well.
I have never had any experience with TAR downloads; are they the same end result ?
Which is the best, TAR or ZIP ?
That’s an old version… please download this package: https://github.com/aferrero2707/PhotoFlow/releases/download/continuous/photoflow-w64-20180910_2145-git-stable-22dd3c5630c359f34fc59e0e23c85c8a4f0937fe.zip
Thanks!
So if I am understanding correctly, that download is a portable standalone Windows application and the plug-in for Windows/GIMP is still in the making.
I am glad I posted my initial question, else I might not have known of PhotoFlow.
Yes, you are correct with your reasoning. It makes sense to me. From what I’m gathering, Adobe is using scripts in the background to alter the end image. As you make changes, it alters the scripts. No changes are made until you save to a flatten’d format.
That’s all well and good, but I’m still not drinking the Adobe Kool-Aid…
Question 1: Is it faster than my method?
Answer: Yes, it is faster than my manual method.
Question 2: Does it produce better quality than my method?
Answer: No. The end quality is always the sum of Quality in + Adjustments made.
Thanks, but no thanks, I will not drink the Adobe Kool-Aid!
We’re already past those days where non-destructive photo-editing is exclusive to Adobe Photoshop. Paint Shop Pro probably has it. But, certainly Photoflow, Affinity Photo, Krita does. And non-destructive editing always applies changes. No need to flatten to see changes.
Non-destructive editing is not exclusive to having adjustment layers. You can have adjustment mask ala smart filters in Photoshop, or adjustment mask in the form of Affinity Photo or Krita. There’s file layers, transform masks, and clone layers. All of those are essentially things that are non-destructive. Also, non-destructive layer effects counts too.
I have been following this back and forth and I can assure you that this kind of debate can be found everywhere on the web. What I would say is that builtin non-destructive editing is quite convenient and keeps the layer, mask, etc., stack more manageable, especially when you are working upwards of 10 layers. Sure, you could group, duplicate, delete and move items; but I am not that agile.
It also helps simplify tutorials. Try following @Elle’s GIMP tutorials; not everyone can follow due to the sheer amount of steps involved.
In the end, it is just another paradigm. Like I said in other threads: someone claims app or method A is better than B and that app B should adopt features from A. It might be superior or it might not be, but to fight over it isn’t necessarily the best approach to make friends and motivate devs.
For my part, I only recently began to experiment with using GIMP. As someone who does astronomical (and planetary) image processing, the availability of adjustment layers à la Adobe Photoshop is indispensable. On that basis I could not recommend GIMP as a program solution to anyone doing similar work.
Then in that case, your options is Krita and Photoflow, and RAW processing software. Krita while generally viewed as a painting software do have adjustment layers/masks, and some generic editing tools including G’MIC support as well as LAB color space support. Photoflow is much more for photographic editing than graphic design.
Recently Gimp has received a 100.000 $ donations, let’s hope non destructive editing will be one of the next features 
I can obviously use Gimp as it is, but i think it is one of the features i miss most (the other ones being a way to easily and graphically record a macro and a native lensfun plugin)
Filter/Adjustment layers are planned for Gimp 3.2, the plan for Gimp 3.0 is a port to GTK3:
https://wiki.gimp.org/wiki/Roadmap
With respect to astronomical image processing there are a number of specialized image processing applications available, both free and paid. For Photoshop, ESA/ESO/NASA (European Space Agency/European Southern Observatory) created the FITS Liberator plugin so that Photoshop would be able to read FITS (Flexible Image Transport System) files - which is the standard format for astronomical imaging. The plugin also does some basic image processing.
With all due respect, I should let you know that I do not specialize on astronomical image processing. So, I can only give options based on fields related to graphic design industries and knowledge of alternatives to Photoshop for certain needs.