A support post and safety fence assembly in which the post has a telescoping inner and outer tube and is supported on a threaded internal shaft coupled to a floor engaging end and ceiling engaging end preferably formed with claws that have a number of sharp penetrating points for firm engagement with a support surface. The support structure is placed on a heatable surface or placed in a process chamber having an infrared radiation mechanism. The L-shaped or T-shaped regions are further dissected into rectangular patches. The absolute values of the differences between the pixel of interest, and its neighboring pixels are computed, and a smaller one of the absolute values is selected as a signal by a minimum value selection circuit.