Handles conversion to and from the CTPK image format used on the 3DS
To dump a .CTPK file: ctpktool.exe file.ctpk
To create a .CTPK file from a folder (folder most contain .xml files generated while dumping): ctpktool.exe foldername
Credits
Normmatt - For allowing me to use code from texturipper and answering questions about the format