Problem with a graphic's file

[Juanfco]

First of all, hi!

Well, I've been seeing a nds game and I have found where the graphic's files are, but
I can't open them. I've seen that they have in the header a word of four letter, I suppose
that it's the name of that kind of files, it says "AT6P" . So, I've looked for info about that format
but I haven't found anything. The game which I am talking about is "999: 9 hours, 9 persons, 9 doors"

Thanks a lot

Juanfco