This is an awesome script you can add to serve images on iPads and next-gen high resolution devices dynamically. I’ll let the description of this script tell the story…  Foresight.js

Foresight.js gives webpages the ability to tell if the user’s device is capable of viewing high-resolution images (such as the 3rd generation iPad) before the image is requested from the server. Additionally, it judges if the user’s device currently has a fast enough network connection for high-resolution images. Depending on device display and network connectivity, foresight.js will request the appropriate image for the webpage.