Looking at this https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/MobileHIG/IconMatrix.html
Does that mean my image sizes should be 25, 50, and 75? What would go into the 1x, 2x, and 3x then?
Ya, the image@1x.png file should be 25x25 pixels, the image@2x.png file should be 50x50 pixels and the image@3x.png file should be 75x75 pixels