Is it legal to use gimp to manipulate copyrighted images?

[Cheetosgoku]

It is not for advertisement or profit, just for stuff like facebook.

[webjnke1]

that'd be personal use, and probably ok

[Techwing]

Technically you need a license from the copyright holder if you modify images and put them on Facebook, although in some cases it may qualify as fair use (if it's a parody, critical comment, etc.). If you heavily modify a copyrighted image for purposes of comment, education, parody, etc., and then put it on Facebook, you probably won't be sued. The more heavily you modify the image, the safer you are.

[Tim]

I have found people that have used my images on their facebook page before. I have sued them for copyright infringement and won every time.

[B K]

No it's not. That's why copyright exists!

It doesn't matter if it's for profit or for personal use - it's still illegal.