>>> Actually, late night spurt — with Huffman trees it's 5,528 bytes and >>> 6,653 bytes respectively.
So going with the lowest figure I make that 330k for the whole map. The watermark isn't a problem as I'd want to make up each screen by hand anyway. I'd be happy to make a couple of test screens up for you to test your routines on but I'd have to put off doing the whole map until after I finish my current project. I don't think it would take a great deal of time to do but neither will my current thing and I really think I should finish one before starting another :)
