That's a great script, Kranu. I'm having fun hosting little bits of HTML on my local network. Do you know if it's possible to link a local HTML file to throw up instead?
On topic though, I found that with your current image dimensions, the Kindle creates a scroll bar and scales the image a little. I reduced them to 595x701 and it works great with no scroll bars and pixel-perfect scaling. I also changed the "100%" scaling to exact pixel dimensions. This is very useful, thank you.