The Rasterbator is an application which creates rasterized versions of images.
Site:
http://arje.net/rasterbator
Download:
http://arje.net/files/Rasterbator_Standalone_1.2.zip
From the site:
"No installation is needed. Just unzip the file contents and run the included Rasterbator.exe application. The application is wizard-like, which means it asks you questions and you click Continue button (or Back if you want to change what you previously answered). There are five screens with different options."