Thanks again. One more question: I was doing some calculations and if I want to print a 24"x24" photo, with each tile being at least 3/4" square, I will only need 1024 tiles in the resulting mosaic. You used 5000 tiles in a similarly sized photo. Was each tile very, very small? Could you see the individual tiles OK? Thanks.
Ooh, I owe you a favor. I just e-mailed you a link to my second draft ... and found out that someone, possibly my daughter, maybe me, had put a diagonal line through it. So I just got the order killed, I hope, at the print shop and I'm uploading the re-done file now. Thank you. Let me know if you don't get the link and I'll PM it to you here.
As far as the size: Yes, they're rather small, but clear. The 2,500 tile one I had printed already has photos about the width of a nickel, about two-thirds the height of a time. They're clear, distinct, and just invite people to stare a long time at 'em.
I went with 5,000 the second go-'round for a reason: Most people are going to see it at a distance most often, so the long-distance effect is critical -- if it looks like crap from distance, no one will walk up to it. And anyone walking up to it can still see it.
Now, in the 5,000-tile mosaic I'm getting printed for my dad now (the one I sent you to the link on), a tile appears to be about 0.31" by 0.42". That's 10.8mm x 8.1mm. Measured in pixels, it's 192x143 or thereabouts. That's on par with a cheap webcam's resolution, but the color and clarity are great.
I'm having the prints done at PosterSigns.com. My first one turned out beautiful, but it was actually my second one -- the first print started peeling off the backing within a week, and Eric, the propreitor, redid it at his cost including the ~$18 shipping. Now we've got a keepsake for a long time. I got mine printed on glossy photo paper with a Gator (like a really strong foam backing) backing for about $10 a square foot. If you're doing 25 inches square, the same thing would cost you roughly $40. This way, I can mount it directly, no frame to run over the pictures -- just take some of those sticky picture hooks. I'll double each side; run a length of picture wire between the pairs of hooks; then run a long length of picture wire between the two smaller lengths so the weight is more evenly distributed. This'll be in our family a long time.