XnView Software

This is my edit on the pic.

http://img412.imageshack.us/img412/3352/img1780edit.jpg

Any guidelines for rotating an image to correct it's horizon? I'm talking about images with an apparent indication of vertical, like a building or anything else that would be vertically level, depending on where the line is on the image and the focus of the lense (assuming we're talking photos).

I ...