Picture resize during upload for EZ Realty Joomla component

I have a website powered by Joomla and EZ Realty 4.2.1 beta. It works fine except that images are not resized during upload. So, what you should do is to add this resizing function to the existing PHP-script. GD2 is available. The target image size should be fixed, so it can be hardcoded into the script, as long as we can find it and change it if we want. A copy of the website is available on a test server. FTP and Joomla admin access will be provided.