the author of this app says:
PPix is a windows application which provides a way to view BMP image files on a handheld.
The Desktop side accepts BMP files as input, converts a color or grayscale image to a dithered monochrome, and generates a .prc application file as output.
Download the .prc file to your Pilot and enjoy the image!
There is one important note, however; you can keep only one PilotPix file or application on your Pilot at a time.