tryTrying to use these modules may help you. (quotes included are from their project pages):
... integrates the Responsive Images library created by Filament Group.
The purpose of this library is to load images in different sizes based upon the resolution of the browser loading the page. This allows for mobile-optimized images.
... provides a "Responsive Images" image field formatter for which you can select both a small (mobile-optimized) image style as well as a large (for normal screens) image style. The image style configuration options are provided by Drupal core.
... solves the problems with images and responsive themes, it allows you to define multiple image style suffixes and their corresponding maximum width.