I searched online and found this comprehensive tip: "Click Picture" then "use Cutout tool". I'm just an amateur and I don't know if it means right-click on the picture or what, and where is this Cutout tool? It's not even mentioned in the Help section.
I'd appreciate your input.
Wolf
contour tool does work on a raster "picture"/ image.
If it's a vector shape then contour tool is available from the toolbars on the left.