Fig. 4.

Example feature maps [(a), (c), and (e)] and feature-value histograms [(b), (d), and (f)] of the co-occurrence inverse difference moment feature computed on the GE 2000D [(a) and (b)], GE DS [(c) and (d)], and Hologic Selenia Dimensions [(e) and (f)] digital mammography systems using a window size of $63{\text{pixels}}^2$ and offset of $l=1\text{pixel}$.