Picture(photo) resizer script for my website

Hi there, I currently have a website ([login to view URL]) and I need to create and install a script that when someone uploads a picture, the picture will be resized automatically without the member having to do it. The way it's right now, if a member uploads a picture and the picture is bigger than 1.5 MB or if the picture has a width of more than 800 pixels or a height of more than 600 pixels, the member will get an error mesages saying they need to resize the picture and I don't want [login to view URL] in conclusion, I need a script that when a picture is bigger than 1.5MB or if the width is more than 800 pixels or if the height is more than 600 pixels, the script will resize the picture automatically without the picture getting distorted. You will have to create and install the script. You will also have to give me the script program in case I need to make changes in the future, I can do them myself. You will have to tell me where in the website you installed the script, The script will have to be flexible so that way i can change the settings (picture size, width and height) in case I need to. I have seen some of this scripts online for free but I just don't know how to go about installing it on my website. The website is create in PHP , the templates are ihtml. i will give you access to my website to install it. it will be nice to have a test to make sure everything is working fine but not sure if that will be possible. any questions, let me know.