Sonic Colors(Dimps) Nintendo DS format (BBG)

Hello,

I have a problem : unknown Sonic Colors DS file formats.
I want to do increased quality textures of sonic colors DS with sonic colors Wii textures.

But when I upload rom in Tinke editor, I found Dimps use a special format : Surprise BBG Surprise for textures !
I opened it in hexadecimal editor and I found the BBG Surprise format .
I have upload the Nintendo BBG logo in the attachment for analysation : http://1drv.ms/1T5U6aS

I know Sonic Team file formats but it isn't the same with Dimps.

Do you know how to open it for modification ?

Thanks