Tropical Freeze Textures: the TXTR format. RTB and Parax pretty much figured it out.

[Struggleton!]

https://github.com/MrRean/ReggieNext-NSM...ter/gtx.py
This is what ReggieNext uses to decode NSMBU's gtx files. I figure it can be easily modified to read the HEAD chunk and use it to load in the GTX data.