Can you send me a file that you’ve processed through LaserCAD, both as a LaserCAD project, and output to a UD5 file so I can have a look at the structure? When I asked what settings you used I was expecting more of a screen shot of the scan settings, not 3 numbers. 
You didn’t indicate, for example, if it was dithered, grayscale, threshold, or something else, or what format the source image was.
Dithering an image in LightBurn uses the DPI or interval you set as the dot size.
PPI has not been added yet for rastering.