imagecopyresampled question

Hi all and merry christmas (and a happy new year)! I use fixed values in this example, but of course it is variables in my script... Let's say I have an image uploaded to the server: 650x400px... Now, I've selected a square out of this image using a flash app that returns the coordinates i've selected. The coordinates are: start_x: 100px; start_y: 120px; end_x: 300px; (or width:200px;) end_y: 350px; (or height:200px;) No I need to use php to take this square out of the uploaded image and make it a 50x50px thumbnail. How should it be done? thanks for your help! .bobo