How to change dock icon when some app has created generic icon images? I want to use a custom app dock icon, and followed instructions found online, which specified the following:


Find image in Finder
cmd-i on file to "Get Info"
Click the little icon in the top corner
cmd-c to copy ... something.
Open the Applications list in Finder
cmd-i on the application to "Get Info"
Click on the little icon in the top corner
cmd-v to paste ... something.


This worked great. Except, not really.

The problem: It appears some app, in associating itself with images, has set all those "Get Info" icons to generic "PNG" and "JPG" icons, like so:

 

The only image app I've installed is GIMP, and I've played with its and X11's settings but didn't find anything. 

Perhaps there's a way to reset PNG / JPG icons? The things I've found online for resetting icons seemed to be about undoing what I'm trying to do, e.g. "I want to bring back the original icon for [someapp], how do I do that?" Which doesn't help me.
You might want to make sure your app is correctly associated (for that you can use the free RCDefaultApp panel).

If you fancy changing icons, you can try the arguably pricey Candybar from Panic inc. which is excellent if you love playing with your icons, but that's all it does, so for 6 Starbuck's Coffee Latte you can do that :p

Please note that if you change an icon, you will probably have to restart the finder (and/or the Dock) for the change to be reflected (Logoff also works).