So I installed LiveHeaders, and tried to get it to show the 304:
https://gfy.com/skins/gfy/gfy_lady.jpg
The lady gives me a response of 200 every time.
Does anyone else see the same 200? Can you find a wesite that returns 304 for an image?
Here is an image that I am serving up with PHP:
http://www.photofight.com/flashgames/b/beerdude.jpg
What would you change in those headers?