I figured it out. Thanks.

Thanks Graechan.

How can I know to use the Gimpmask.exe?

Updated
I find something here
http://gmask.wikia.com/wiki/Tutorials/FL_Flip

Deskew doesn't seem to be loading properly. When I start gimp, I get this error:


I am using Gimp 2.10.20 64bit

Did you add the two library files?

Where do the two library files go?

I would put them in same folder with the plug-in, and place that folder in the user plug-ins folder to avoid conflicts. That's how I always did (do) on Windows with the plug-ins that require extra libraries.
Just like with G'mic.

I will try that and see what happens.

EDIT:
Here is where I put the plugin and the dll files:



This is what I get on start up:

Move that folder to Global (in Program Files) and try again.

You mean this folder?

Mahvin, I tried what you suggested and I still get the error on start up. I have placed it back in my downloads folder.

With the upsize script, is it similar to the scaling tool?

For starters, take a small low quality image and boot it up in GMIC under the Upscale filter. Run it and you'll see what it does. Scaling an image does not retain image quality, it eventually becomes pixelated, whereas upsize or upscale works to maintain the image quality even at a larger resolution. Minus all the fancy technical words, that's it in a nutshell.

Sometimes, things just don't seem to work. It's working on my system and we have the same set-up.