I wonder why isn't it implemented in the GUI? I know git has a content approach vs. single file approach but sometimes single file reverting is crucial.
For instance an .png graphics file from a few commits before is needed.
Probably I need to do a checkout but I'm still not sure as the concepts sometimes escape me.
If you know how many commits back you need to go, you can use:
git checkout master~5 image.png
This assumes that you're on the master branch, and the version you want is 5 commits back.
To expand on Ron DeVera's post, where he mentions master~5, you can use any reference to a git commit, including the SHA-1 if that's most convenient. The point is that the command looks like this:
git checkout [commit-ref] [filename]