PNG

From Graal Bible

The PNG abbreviation stands for Portable Network Graphics, and is an image format supported by all recent Graal clients and most modern image software. It is an open format and is generally considered superior to GIFs in almost every way (although PNGs do not support animation). As of Graal4, PNG files with alpha blending (commonly called semi-transparency) and 24-bit color support are compatible with Graal.