I got this info from another forum. Here's the original thread. The original poster was making large prints from a toy digital camera. To avoid a pixelated pic, he used a program called The Rasterbator that "hides the pixels behind a raster pattern" so you get dots instead of pixels. After choosing the dot size, the program saves your pic as an Acrobat PDF file, which prints the dots as vectors (so they aren't pixelated). Here's the program's website with an online version and a Windows program, and here's a Java version which you can run on Mac OS X.