Convert bmp to gg Online: bmp2gg
You can use Tom's Editor to easily convert images from
Microsoft Windows bitmap .BMP to Koala Painter 2, packed
Tom's Editor is a free, online image manipulation and converter program.
Go to Tom's Editor
Format created by Microsoft for their Windows and OS/2 operating systems. Images can be compressed or not.
Koala Painter is a Commodore 64 program do edit images. GG images are packed using RLE compression.