Resize Image on the fly for Download Purchase

Hi
Does anyone know of a plugin or method to do this.

I have a client who is selling his images in 3 sizes. At the moment we upload three copies (sizes) to Amazon S3 that are given to a customer on purchase (Woocommerce).

Is it possible to upload just one size (the largest one) and then depending on which size the client orders, it is resized and delivered to them.

– Has to work with Amazon S3

OR: Is there a way to upload the largest size and then have it resized to medium' andsmall’ so whichever is ordered is served rather than resizing when ordered it’s resized on upload etc.

Ernie