Limitations
Both TGA and DDS image files can be used.
When importing an image, be sure that the image's dimensions are a power of 2 (Needs Verification*). Not complying with this limitation can cause the Galaxy Editor to crash when attempting to load the image.
(*DDS files if they are compressed by dxt-5 method need dimensions that are divisible by 4 --Knallertton (talk) 14:30, 18 March 2017 (UTC))