This is a fun tool to edit images and that allows you to generate sound from them.
Note: It seems that the software hasn't been updated for several years - the version linked to this page is the latest to exist.
Coagula is an image synthesizer; it is both an image editor and a sound generator from an image. It can generate rich and complex sounds. It has all the useful tools to draw and to create images. It includes lots of specific tools that cannot be found in other image editor.
This software can be downloaded and used for free.