Is there a way to convet images into pixel art for terraria/tedit

[MorningSTAR-αΩ]

I'm wondering because I want to see if I can get my signature (not the vocaloid one) into the game

 

[Varsia]

A simple, but sometimes a bit bad way of doing it is simply shrinking the image down to a smaller size without interpolation (so that it looks pixelated) then doubling the size without interpolation.
As I said, it doesn't always work well.

Or you could just pixel art it yourself.