Hi NAwlins Contrarian, thanks for your thoughtful post.
You're welcome, and glad you think it so.
I have used GIMP since 2003 or 2004, maybe even version 1.2 or whatever was the last pre-2.0 version. GIMP has a ton of capability, but it also has some glaring weaknesses:
(1) very few of the operations are non-destructive, so if you want to go back and tweak an adjustment you made four steps earlier, at best it's a PITA and at worst it's impossible; and
I am using GIMP 2.10.38
That is certainly interesting, so far as detailed in my first post I am only doing fairly simple steps to get from a RAW to a print or web sized jpeg. What you say means I guess if I start doing more complicated editing I will have to watch out.
As raw converters have gained more and better capability to do some of the things I used to do in pixel editors, and (at least in the raw converters I use) non-destructively at that, I use pixel editors less and less, especially for "fairly simple steps to get from a RAW to a print or web sized jpeg". Indeed, have you checked whether you can perform those operations in the raw converter, and if you can, then why would you use two pieces of software (raw converter + GIMP) to perform what one (raw converter alone) can do? That's not to say that GIMP (or Affinity Photo or whatever) offers no advantages for
some of those operations, but fewer and less over time.
The more complicated editing where with GIMP you have to watch out becomes an issue where your edit is e.g. eight operations and you may want to create different versions. If you decided to modify something you did three steps ago, in most cases your only option is to perform multiple undos, redo the step as modified, then redo the subsequent operations. There are limited undo levels / memory for them, and sometimes redoing the subsequent steps is laborious and/or difficult. The great thing about a largely non-destructive editor like Affinity Photo is that it's quick and easy to go back to something you did ten steps ago and modify it, remove it, or temporarily disable it. With GIMP that works fine for text layers, otherwise not so much.
(2) although GIMP relatively recently gained 16-bit operation, it still has substandard and nonstandard color management and related issues, so unless you're happy limiting yourself to GIMP's slightly-nonstandard version of sRGB, it has substantial issues.
At the moment I am happy with my output using GIMP. I have a tendency to make my images a little punchier by use of levels, reality is less of a concern at the moment colour wise.
You'd probably get as good or better results doing that sort of global parametric edit in your raw converter.
However, GIMP remains something I use for certain purposes. Its abilities to easily and precisely crop and to place / move around various layers etc. makes it great tool for compositing and similar tasks. Building a collage or similar? GIMP is very good.
Aha, good to know, thanks.
I am hoping to learn some new GIMP tips and tricks with this thread.
My main tips, related to the limitations I raised above, are to think carefully about what order of edits will provide the maximum flexibility to produce changed or alternate versions with the minimum of undos or whatever.
And toward that end, you can save intermediate versions along the way, e.g., perform three basic edits, save as an XCF, perform three more edits (like crop, resize, and sharpen for a specific output size and use) and export those as a JPEG or TIFF but
don't save over the XCF at that point (at most, save as a different XCF). Then you can easily go back to the first-saved XCF and start with the three basic steps done and only the three final steps to go to produce a version for a different use.
At the moment I find I am using unsharp mask to sharpen all of a pic before exporting to jpeg - I notice there is also a sharpen command which I think I might prefer to USM, but I can't work out how best to use it. I would probably like to select the key subject with a blurry selection and then just sharpen that bit of the image. Is that easy to do?
GIMP's multiple alternative methods and algorithms to resize / resample and sharpen or blur are one of its stronger points (even if they are not as sophisticated as Topaz's or even Adobe's). You can of course use the selection tools to select only part of the image and sharpen (or blur) it, but that selection process is for most purposes rather crude. As someone else said, if you want to e.g. selectively sharpen the main subject without affecting the rest, make a 'sharp layer' and then paint on a layer mask with varying area and opacity to bring out that sharpness only where you want it.