I have a problem and I hope you can help me. So, I've been trying to hack some Japanese Konami NES games, but I ran into something. When I look at the tiles, used for letters, they all look scrambled and unrecognizable. A good example of this is "Dracula II: Noroi no Fuuin":http://s34.photobucket.com/user/AlienX97/media/CVII-1_zps43fd6895.png.html
I thought there was something wrong, but after I looked at the Japanese version of "Contra", I saw the same thing, except this time, the letters were large enough to see what's going on. Apparently they used some kind of compression that allows two graphics to be stored in one tile. If you look closely, you'll see both, with the "main" one in a lighter shade and the "hidden" one in a darker one. Byte shifting in YY-CHR reveals the "hidden" graphic, but makes the "main" one become darker. Trying to just edit the tiles by drawing normal English letters doesn't work, as it screws up the rest of the tiles, when the game is running. So, my question is, how can you decompress the graphics? I've seen English translations of "Gryzor"(the Japanese "Contra"), so I know it's possible. Can anyone, please, help?