The the GIMP, http://http://www.gimp.org/ . Despite the dodgy looking URL
and suspect name it is fine. It runs under a number of platforms, for
windows you will need to download an additional package first but the
website will tell you and its all quite simple.
Look under tools - transform tools - perspective when you have load in a
file.
This may have changed a bit as there has been a new version out lately.
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments. After that, you can post your question and our members will help you out.