One thing that I would try that should help is doing a regular emboss along with the image emboss
When you do this to get the .18 depth that you want. Via a radius or ellipse subtracted.
Then the image goes on top or cut out of the regular emboss to add the detail that you want.
I used a slice radial because you can use a boundary to contain the tool path.
Then I tried a planner rough a finish
