The choice of the single parameter wh has turned out to be noncritical. It may be automatically selected by using prior knowledge about the image position of the checkerboard area and its amount of squares in each direction, if necessary. However, the length of the checkerboard pattern must be chosen with care, since it influences the quality of segmentation to a large extent. In turn, this choice is dependent on the desired image resolution, because a sufficiently sharp image of the background pattern is required3.