I’m trying to build a simple application that will recognize the values of two 6-sided dice. I’m looking for some general pointers, or maybe even an open source project.
Image recognition is non-trivial. You're going to have to constrain the input data in some way, and it looks like you've given this some thought.
Your question reminded me of a blog post by the author of SudokuGrab, which is an iPhone app that allows you to take photos of a Sudoku puzzle in a newspaper, and have it solve the puzzle for you. In the post, he discusses several of the issues that you will face in solving your problem, and how he overcame them.