Photo resize script

Hi there, I have a website where and via the control panel I can control the size(in KB) the width and height(in pixels) of the pictures uploaded by members in the website . The problem is that for example, if I setup the values at 500KB, width 300 and height 400 pixels and the members exceeds any of those parameters, they will get a error message saying to adjust the size, width or height of the picture. I need a script that will automatically adjust the size, width and height of the picture to the value I setup through the control panel of the website when a member tries to upload a picture. The script will have to support jpg, jpeg and gif. You will have to install the script as well on the website. Half payment to GAF escrow once you selected. Other half once the project is completed. Thanks,