Image download in difference size

Hi Friends,

I have created image blog. i want to embed such gadget which allows the visitor to download in difference size.

Can anybody help me out how it can be done ? If any other template which having such kind of feature then please suggest me.

Thanks in advance

What software are you using?

Hello everyone,

Can anyone also suggest me how allow the user to download image in different size ?
provide full information with step by step.