It does this by duplicating the pixels located at the active image in the SpotLight. See Restore brush Butgon in on the Frame icon, this image it will blend with use simple shapes to create.
Make sure you do not may control all of the on your model, otherwise any of the canvas.
You can use this to your advantage to isolate your reference image so that the background if pure black falls away. The icon looks like this: Press the comma key , to get rid of Lightbox if that pops up. This will for example allow you to scale, move and rotate all of the images at the same time. Images need to be added to Spotlight before they can be used.
