Abstract: A control apparatus for processing the electrical signals generated by an optical ratiometric color sorting scanner, said apparatus generating signals to cause the rejection of articles which differ in color and/or size from predetermined limits. In the scanner, two electrical signals are generated which are responsive to two different spectral regions or pass bands of the radiant energy reflected by the product being sorted. These signals are superimposed on a slowly varying signal responsive to the standing background light. The control circuitry processes the signals to delete the standing light signal and spurious noise signals and determines if the ratio between the signals is greater than or less than a predetermined value, or alternatively, determines when the ratio between the signals is not within a predetermined acceptable range and generates a delayed reject signal thereafter. Other circuits provide signals to a meter for displaying the present reject rate and particle feed rate.