I use Linux as my primary OS, so Photoshop is not much of an option. Plus, Gimp, along with Krita, InkScape, Scribus and MyPaint, covers most of what I need for 2D graphics. If I really felt I needed Photoshop, I would buy it, but I don't.
I know a lot of hobby users pirate Photoshop, which I think hurts Gimp more than it does Photoshop and Adobe. Many of the users who pirate Photoshop, wouldn't pay for it in the first place. If piracy was not an option, they would be looking for other alternatives, which would mean Gimp would have a larger user base, which would lead to more feedback and bug reports for the developers, hopefully more donations and likely more developers working on improving Gimp. And they would likely stick with Gimp, if they later began doing professional work.
The argument you generally hear against Gimp is that it is difficult to use, and that it lacks CMYK, 16-bit and 32-bit support. The first point stems in large part from people being used to Photoshop, and when they move to Gimp everything is different. The same would apply to a Gimp user, moving to Photoshop. The second point is only really relevant if you do professional offset printing, and know what you're doing. Half the people screaming about CMYK support, don't really know how to handle CMYK correctly in the frist place, but if you do really need CMYK maybe Photoshop is a good option for you. As for 16/32-bit support, it's on it's way, so will be in future versions of Gimp. For now Krita is a great alternative for both, even handling it better than Photoshop, where half the tools get disabled once you switch to 32-bit mode.
That said, I've bought a number of 2D graphics programs through the years, and two of them still have their uses in my tool chest. These are MangaStudio EX and FrameToon.
MangaStudio EX is kind of unique, in that it's focused on 1-bit drawing. That is black and white pixels only, with no anti-aliasing og grays. This is great when doing b&w print comics, as you can easily work at very high resolutions without a super computer and get sharp lines at 600, 1200 or even 2400dpi, as each pixel is 1/24th the size of a normal color pixel so uses 1/24th as much RAM.
The other one is FrameToon, which is a Japanese 2D animation program from the developers of openCanvas. I actually don't think it's being developed any more, and there is no English version of it, but it works great. It's likely the work being done no animation features in Krita will make it a good replacement for this at some point. TVPaint is actually a great alternative here, which has a Linux version, but the price is a bit steep and since I rarely do 2D animation it's now really worth it.
gbarkovalev: If I understand your post correctly, you're looking for a way to create a selection and round of the corners. There are two ways to do this in Gimp that I know of. Select and are using the lassoo tool, making sharp corners. Then choose Select>Distort... from the menu and set Spread to 0, Granularity to 1 and Smooth to how much rounding you want. The other alternative is to use paths, which have bezier handles you can accurately adjust the curvature with, and then turning it into a selection.
obs...didn't intend to write a whole essay here.
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