Tutorial time!
1. Get Gens KMod
http://www.spritesmind.net/_GenDev/index.php?page=gensK(You can use other emulators so long as they have the right kind of features.)
2. Load a ROM
3. Get to an in-game moment where you want to start mapping
4. Set it to Frame Skip 0 (ie. render 100% of frames even if it slows down) and then choose "Screen Shot each frame". It'll start hammering your hard disk as it writes 60 images per second.
5. Now move around in-game so everything becomes visible. Here's a video of me mapping a Micro Machines 2 level:
http://video.google.com/videoplay?docid=-1930249089414408138I died a few times but it's not the end of the world, so long as the screen moves smoothly throughout.
6. This game has a few on-screen status images (clock, lap count, etc). I made this mask image which is black wherever I want to get rid of them (I also want to get rid of the player's car sprite):
7. Load these all up into Screenshot Autostitcher and stitch with the settings set to search 16 pixels, match 50%/95%, scrolling both ways, decimate 1, not reverse order. You get this:
http://img293.imageshack.us/img293/5589/stitchedab0.pngAs you can see, it's just a few more screenshots away from being complete.
