I recommend putting it in Printer NVRAM if you can. It is much faster to print and the image quality, IMO, is better. Then you need to use an <XCT> Tag in your Template to tell the printer to print the in-memory image, like:
<XCT>29,40,76,6,0,48,69,32,32,1,1
For pulling logo from your computer drive (which is easier, but generally slower), you use a <BMP> Printer Tag, like: