A surface object comprises a surface with a boundary, the surface having a background color. At least one optical marker is provided on the surface for assisting of image processing for improving appearance of an image of the surface with the boundary. At least one optical marker includes at least one color which is lighter or darker than the background color and the color different ΔE between the background color and the at least one color of the optical marker being between ΔE=2 and ΔE=18.