CTPK

CTPK is an archive format commonly used in 3DS games, including Persona Q and Persona Q2. It contains TGA images.

Kukkii
Kukkii is a part of the Kuriimu suite of editing tools. It is capable of extracting and displaying images from CTPK files, as well as importing and exporting them as PNGs. It can be found here.

CTPK Tool
CTPK Tool is a Commandline program capable of extracting and repacking CTPK files. It can be downloaded here.