[HS2] - [About tattoo mod's color]

[crazy-night]

I 'm following the tutorial on the wiki to make a texture mod. But I'm confused that colorful textures loses colors in the game. It seems that only two colors will remain. I'm wondering whether there is a rule about that. How can I make a colorful tattoo mod? p.s. I've known overslays but I prefer mod since it's convenient to adjust.