I'm using GIMP 2.9.6 64-bit with Windows 10 and I've just been trying to install G'MIC in order to use inpaint, but things haven't worked quite as I hoped and so I'm asking if anyone can point out what I'm doing wrong.

I'd discovered from Google that you need to replace libcairo2.dll with an update, and so I did this. I installed gmic_gimp_qt_win64 (version 2.1.5) to the default location and then in GIMP Preferences under Folders/Plug-ins set the path. On re-starting GIMP the log shewed a long list of failures of gmic plug-ins to run, but G'MIC-Qt was there under filters, and I could duly select a portion of an image, fill the selection with red, and then invoke the inpaint repair option. However, I have been totally unable to get this to work as I have seen in some of the examples on the web (after downloading some of those files to try for myself), and the "finished" versions always ended up with a hard red line marking out the area that had been selected and an appearance of being rather masked - sorry I can't put it better than that. (Just to be sure that there wasn't a problem with the downloaded images I tried Photoshop Elements Content Aware Fill, and that worked perfectly.)

I have tried using the Zip version of G'MIC and I have tried alternative locations for the files, but what happens is the same every time. Has anyone had the same sort of experiences and discovered what to do about it? I should be really grateful for any help. I'm attaching a jpeg of the log-file with the error-messages.

Typical question for Rich (Rich2005).
He comes often also here, but his main site is Gimp-Forum.net, where he is one of the Administrators. I suggest to post your question also there.

I see you

@Rinbad

Lots of info about the terminal error messages. Ignore them until something really does not work. Gimp thinks all those gmic files are potential individual plugins. Do what it says on terminal, minimise it, then you will not worry

Could have done with more information about the inpaint filter, such as which one.

Guessing this you used inpaint[patch based] and output to a new layer. https://i.imgur.com/Et72iaT.jpg

The problem is shown there, (default) anti-aliasing is on, then made and filled a selection apply the filter gives this. https://i.imgur.com/MkK5tnb.jpg a red outline

Turn the anti-aliasing off before making the selection, then apply the filter. https://i.imgur.com/upgSymI.jpg

Another way is use the pencil tool and paint in a mask, pencil tool = no anti-aliasing.

Thanks for both replies. What happened was that I'd been seeing advertising for Snapheal for Mac so looked what there might be for Windows on Google and came up with the G'mic Inpaint (multi-scale) filter for GIMP. So it was multi-scale that I was trying, not patch-based. I'd then found a couple of demonstartion videos on-line and had tried to do what I saw there—with no great success, as I said.

Rich's advice about the anti-aliasing seems to be the crucial factor. I've tried that both by switching it off if using the lassoo tool and bucket-fill and also by using the pencil, and the result with both is fine, regardless of whether I output to the original (the default) or to a new layer. The result is very good indeed, the only hint of a complex removal being a very slight shadow where the original was (which does not happen with the Adobe equivalent)—but I am being pretty criticial to notice it! Here's the original (screen-grab from a demo of the filter) and the result after me using multi-scale and following Rich's advice.

Thanks again!

Thank you rich2005, I also learned something here.