I want to develop a PHP website feature where users sign up, get a javascript snippet code that display an image on their site, and let's me track the number of visitors, unique hits, clicks and average visitor duration on their page. Is that something that should be done with some open source analytic software such as http://piwik.org/ or it's pretty doable on your own?

If I had to do it myself from scratch, I would use image/pixel as a way to track the visit, drop a cookie with javascript snippet to track uniques, track clicks based on image click and redirect, and not sure about the bounce rate.

Any thoughts or opinions are welcome.