How to engrave PNG color files?

A laser “engraves” in shades of gray (or brown or whatever the material allows), so you may want to convert the image to grayscale before sending it to LightBurn. This will let you to control how the colors become grays, rather then depending on LightBurn’s automation.

Some color-to-gray conversions using GIMP:

The tools are:

Original image for comparison
Mono Mixer
Desaturate
Color to Gray
All of those tools have (many!) controls to adjust the conversion process and change the output, but I just used the defaults. I have no idea where the odd background came from in the last image …