Developer James Thomson posted to Twitter that he noticed iOS 8 automatically chooses to load images at a triple retina resolution rather than a double retina resolution like iOS 7 does. 9to5Mac was the first to spot this tweet and has also independently confirmed the same.
Read more: http://www.businessinsider.com/iphone-6-display-rumors-2014-8#ixzz3C68eXPVw