A diagnostic imaging system in an example includes a high frequency electromagnetic energy source, a detector, a data acquisition system (DAS), and a computer. The high frequency electromagnetic energy source emits a beam of high frequency electromagnetic energy toward an object to be imaged. The detector receives high frequency electromagnetic energy emitted by the high frequency electromagnetic energy source. The DAS is operably connected to the detector and programmed to employ a threshold to trigger a filter operation on a pixel, in a basis material decomposition (BMD) image of a plurality of BMD images, through comparison of an actual noise ratio between a pair of BMD images, of the plurality of BMD images, to a theoretical BMD noise ratio value. The computer is programmed to employ a correlation in noise distribution of the plurality of BMD images to reduce image noise in the plurality of BMD images.