I made this project with the intention of adding color while engraving a tile.  I used the original photo to estimate where the colors would fall on the tile.  I actually painted 3 tiles in the same color pattern and used various power levels and speeds until I got the tone just right. I began with power level 25% but it was not strong enough so I tried 30%...then 35%...I checked in on the "engraving process" from time to time to see if I was getting the right tone.  When I saw the power level was not working, I cancelled the project and tried a new setting instead of wasting the entire painted tile.  I let it go about 1/3 of the way to get a good idea if it was working.  Finally I found 35% was close and 40% was just a bit too much (it dipped into the white tile surface erasing all of the color).  I dropped the power level to 38% and felt comfortable with the outcome so I engraved the last prepped tile and it worked!
I debated whether or not to seal it with clear glaze but I took the photo before I did.  I didn't include the photo because this was a memorial photo of a client's dog and aside from sharing it with my fellow xToolers, I doubt anyone would need this photo.  The settings are all there so at least it's a starting point for you.  Although it was initially estimated to take 19 min, it actually took about 27 min.