Makes me wonder if evil-doers could encode a program into the pixels of an image that would unwrap and execute when the picture was opened.

Claverhouse said:

Makes me wonder if evil-doers could encode a program into the pixels of an image that would unwrap and execute when the picture was opened.

Encoding a program would be trivial. Finding a bug to exploit to get the embedded code to run on the other hand... In any case always keep your browser updated.