Abstract: A method for three decision mode selection of a thresholding algorithm is disclosed as is a thresholding mode switch having a three decision mode determining capability that is particularly useful for facsimile-copier devices in making printed copies of mixed format documents. The thresholding mode switch uses a reflectance difference algorithm for switching between a gray-scale thresholding algorithm and black-white thresholding algorithm to enhance the quality of prints made of mixed format documents presented for copying. A gradient constant is established for each picture element (pel) of the document then presented for copying and a determination is made at the thresholding mode switch as to which range, of three predetermined ranges, the gradient constant falls within, with this determination being then used to control the thresholding algorithm utilized in making that portion of the copy relating to that particular pel then being copied.