This is the most simple one.
1. Take full image url
2. Add a "m" at the end of the file name (before the type)Code:http://i.imgur.com/LAAc2.jpg
3. Add [img] tagsCode:http://i.imgur.com/LAAc2m.jpg
4. Add [url=fulllink] tagsCode:[img]http://i.imgur.com/LAAc2m.jpg[/img]
5. DoneCode:[url=http://i.imgur.com/LAAc2.jpg][img]http://i.imgur.com/LAAc2m.jpg[/img][/url]