RokQuickCart uses the powerful litebox type plugin, RokBox, for its images. RokBox is a popup type plugin that allows the loading of images, flash, PDFs, websites and other media items in a javascript powered window. It is extremely useful in consolidating space and not loading full-sized elements when they are not necessary

The extension has a RokBox mode, simple load your image into the RokQuickCart administrator, at Admin → Components → RokQuickCart, for a particular product and the extension does the rest.