How does "create from image" decide where to place the circles?

I'm wondering if anyone knows what criteria the "create from image" feature uses to place the circles on an image that has been uploaded. It doesn't seem to be a complete spread of the most prominent colors, nor does it seem to be based on the overall coverage that each color has (although it's close sometimes). I like to use this feature to determine what the actual color palette of a photo looks like when mapped onto a color wheel, but I usually have to move the circles to choose the most dominant colors manually before mapping them onto the wheel.