An x-ray source (32) for performing energy discrimination within an imaging system (10) includes a cathode-emitting device (82) emitting electrons and an anode (81) that has a target (80) whereupon the electrons impinge to generate an x-ray beam (93) with multiple x-ray quantity energy peaks (116 and 120). A method of performing energy discrimination in the imaging system (10) includes emitting the electrons. The x-ray beam (93) with the x-ray quantity energy peaks (116 and 120) is generated. The x-ray beam (93) is directed through an object (44) and is received. An x-ray image having multiple energy differentiable characteristics is generated in response to the x-ray beam (93).