How can you change images src attributes in mediawiki to access a CDN?

We have a mediawiki with lots of images http://bbref.com/bullpen/ and want to serve images via our CDN for obvious reasons, but I can't quite grok how to set things up in mediawiki so that we can get

img src="/local/path/to/image.png"

to output as

img src="http://cdn.example.com/local/path/to/image.png"

The CDN 开发者_开发百科is up and running, so I don't need any help there. I just need the fix for mediawiki to change image srcs to point there rather than with a relative link.

thanks, sean

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Take a look at the following

• $wgUploadBaseUrl
• $wgStylePath