Go to System → Settings → System
Easy serve high-resolution images to devices with retina displays. After enabling please clear the AbanteCart images cache
Retina display devices show more pixels per square inch to allow for a crisper display and in order not to let the resulting display appear too small elements are mapped to 2 pixels instead of one (for retina) (otherwise they would be tiny).
This means that if you have a standard image of 100px * 100px then it is automatically resized to be 200px * 200px by the retina device so that when it is shown on the denser pixel display it once again 'appears' to be 100px x 100px (because of the double density pixels).
If enabled AbanteCart will generate two files for each of your images, regular size and @2x version image with a resolution twice higher. This will require more server resources but all images will be crisp and not blurry!
To generate Retina Images Apache module mod_rewrite must be installed and you need to rename the root htaccess.txt file to .htaccess
mod_rewrite is something that is installed on your server by your web host. You need to ask your host (or look in their help guide) to find out if you have it.
rewrite base note
If you access store with sub-folder like http://www.mydomain/subfolder make sure to change RewriteBase / to RewriteBase /subfolder/ in the .htaccess file.