I believe you are half right here. Unfortunately, it is not the source image’s complexity that is the problem. I don’t think the smooth gradients are either.
It’s the pixel density of the output to the Laser that is the limiting factor at the moment. That increases by the square inches of the engraving, the engraving speed, and the LPI setting of the engraving. It doesn’t matter if it’s black or gradients or checkerboards.
Nancie, What I think you’re running into is trying to engrave the entire 12x20 half of your sign in one pass. That’s going to be too much engraving for one pass.
Here’s a description of what you’ll probably need to do to get your engraving to work at the moment:
The other thing you may already know is that you can’t engrave edge-to-edge on the 12 x 20 area. The grey hashed border areas in the preview window show your maximum engraving size.
Good luck!!!