A few weeks ago I had some success with attaching a wood burning tool to my CNC and doing some cool designs. Then I got to thinking about doing photographs when I stumbled onto some software that would convert an image to a raster and then speed up or slow down the side to side movement of the CNC. The results are pretty awesome after a lot of trial and error. This is still a work in progress but the software works, is free, and can do some really cool work. The software is called, “G-ray” and the latest version is 4.1 (although the software was written years ago)
The software link: http://hobbycncart.com/forum/46-234-1
There are some really cool pictures further down in the forum discussion.
Another discussion on it was found here: https://www.machsupport.com/forum/index.php?topic=24776.0
Best of luck and do share your results!
DIY CNC Woodburning Photographs! – With Free Software!