Here Tim Greenfield demonstrates how to shrink an image and even increase the compression on that image before storing it on your server.
Allowing users to upload images is becoming common place for many
websites and applications today. Equally common is the fact that most
cameras and phones today produce very large and high quality images. On
the other hand, very rarely do you actually want a high resolution /
low compression image sitting on your server; nor does the average user
know or care enough to manually reduce the size of their image before
uploading it to your site.