I've been writing some of my own greyscale engraving code recently. I have written both ends before (in a project that didn't make it to the blog) but this one is a PC sender program connected to a GRBL controller in my Whitetooth laser. The fun part is that the image was captured from a drawing my wife did for me via my webcam.
Yes, I know it's only on/off and not real greyscale.
Yes, I know the image is mirrored.
Yes, I know it is titchy compared to the original.
It's a really cute picture of a kitty though, now move along.