Select image size to download

I have uploaded images to my album and have set it to automatically generate 3 different sizes which it does perfectly.
Visitors may select images to be added to a cart for later zip download.
Is it possible to:
1. Select that all images that go into a cart are of a particular size?
or
2. For each image that they want in the cart they can select 1 of the 3 different sizes I have created?

I am using Gallery2 2.2.4.
Can anyone assist?

Thanks and regards.