If im going to build an image hosting website, I need to find out how much processing power I need. Let say a user uploads 500 photos in a bulk. How much resources (CPU and RAM) will it take to process these images? (For example, we need to take all those images, create separate versions with separate resolutions and upload them to amazon S3). I need to find this out to pick a good VPS for the site. Also please note that not only one, several users might upload at the same time.