Decomposed images of the anthropomorphic head phantom. Within each image set, the “bone” image precedes “tissue” image. In the bottom-right image, the dashed circle indicates the location of the ROI used for mean and noise STD calculations. The tuning parameters of the IDEM algorithm, (β,δ), are set to (0.72, 28.1) when spatial weighting is not implemented and (1.00, 27.2) with spatial weighting employed. Display windows are [0.01 1.4].