Because we work with a number of sprites, the kind of specialised diff views provided by Beyond Compare would be ideal to see which one of 2 versions I'm after when conflicts arise.

I've already configured Git to use Beyond Compare as my primary diff and merge tool as described in their integration guide — it specifically goes into how to configure TortoiseSVN to use it for images, and I've found these articles talking about .gitattributes in general and how to script interactions from a *nix shell — but it's not obvious to me how I can use the advice provided by these guides to make a simple change that would say "use the default diff & merge bindings for files determined to be images, too".

For the record, I'm doing all this on Windows :P