Supposing that we know nothing except the url of image (smaller size e.g. 150x150)
http://xxx.com/wp-content/uploads/2014/06/test-image-150x150.jpg
What is the best way to get its full-size image url from the url above?
or
Just easily remove the prefix "-150x150" ? (I'm not sure if this is proper since i need best practice also.)