Seven Challenges in Image Quality Assessment: Past, Present, and Future Research
Figure 6
Demonstration of how spatial filtering (local frequency-based decomposition at a particular scale and orientation) mimics the initially linear responses of an array of similarly tuned neurons tiled across space. Note that actual V1 neurons cannot yield a negative response; however, negative values are still computed during the filtering and are assumed to model the responses of another array of neurons with a of-out-phase tuning (i.e., with an inhibitory central region and excitatory flanking regions).
