System--> Configuration -->Smart Product Image

You can set image size for different screen resolutions

Magento Full-width template - Smart Product Image - set image size

This is a guide on how to specify image size on the product page for different screen resolutions in the Full-width responsive Magento template.

Full-width is an extremely customizable and easy to use responsive Magento theme. It has unlimited color variations in style, 15 Magento extensions included and many more features.