Picture Variants

Hello,
How can I use a picture already uploaded on the server.
So I have a shirt, Let's say Color Red, all variations of sizes S, M, L, XL, XXL, use the same picture, But in admin panel, on picture variants i have only the option to upload picture from my PC,How can i use a picture already uploaded on the server ,so I do not have to upload the same picture again, for every variants.

Sorry For My Bad English.