Bioinspired figure-ground discrimination via visual motion smoothing
Fig 2
The lobula network solves figure-ground discrimination problems based on the noisy local motion measured by an EMD array.
(A) One example of an input frame. The stimulus (80% contrast) consisted of a textured foreground figure (34° × 34°, in the red boundary) moving to the right at a speed of 66°/sec against a similarly textured background (stationary) (S1 Video). The red boundary was not present in the actual stimuli. Left: the original frame. Middle: the preprocessed image. Right: the foreground location (white area) and the background (black area). (B) Snapshot of the response profile of the ON+OFF EMD array. To examine the profile (top) at a higher resolution, the area outlined by the cyan boundary was zoomed in and disassembled into rightward (lower-right) and leftward (lower-left) components. (C) Same as (B) except that the EMD response profiles in the ON and OFF pathways were also displayed (upper row). All data were displayed as a grayscale matrix. The area in each panel outlined by the white boundary was magnified and disassembled into rightward (lower-right) and leftward (lower-left) components. Note: the element values were enlarged by 10-fold in the lower panels to facilitate an inspection of the difference between the numbers of elements of two components. (D) Foreground figures detected in the Ir module under different receptive field conditions (labeled at the top). Upper row: membrane potentials of the units in the Ir module. Lower row: output of the Ir module. Red boundaries indicate the figure’s locations at the corresponding instant in time. The membrane potential time courses of five units (marked by white circles) were further examined under two receptive field conditions in (F). (E) Membrane potentials of the units in the Lr module (simultaneously recorded with those in (D)). (F) Time courses of the membrane potentials of the five units marked in (D). The curves are color-coded according to the marking colors of the corresponding units in (D). The data in (A-E) are presented based on the input frame in (A). The synaptic weights of the projections between lobula modules were set as αlo→lo = 2.