title: Convert image to GRF format
body: <p>I have a Zebra Gk420t printer that allows me to make stickers and I need to print an image on them. I read that the images must be in GRF format (pure hex).</p>
  
  <p>Someone knows how can I convert the images to GRF format in Linux? I read about Ztools software on Windows, but nothing interesting on Linux...</p>