This is useful, as the tiles are usually found in 1 bitplane mode. Okay, here comes the hard part. Here's how the 16x16 tile format works. As you can see, the tile is split into 2 12x8 halves. This makes double letters easily without having to scrunch 'em up in one tile.
Some japanese chars have part of the tile as the first half, and part as the second half.
You can do this too as a method as making wide tiles. Finding characters of these large tiles are easy. Also, FF usually is a space, so you will have to count spaces, too.