I just found this totally awesome application called The Rasterbator. I know it sounds like some bad thought up porn product, but it is actually totally amazing. The Rasterbator creates huge rasterized (dotted) images from any picture using several sheets of regular-sized paper to turn into giant posters.
Choose your image, crop and resize if necessary, and the Rasterbator will create a multi-page PDF file. Try the Rasterbator online or download a copy of the software. It’s totally free and you can change the size of the dots and how many sheets of paper you want to use.
I can’t wait to use this on some paintings. I have already started playing around with different ideas.