Retina

• It turns out that your retina (which is really part of the brain) acts as a bunch of on-centre off-surround detectors, and off-centre on-surround detectors, of varying sizes.
• So, what goes down the optic nerve is the output of these receptive fields.
• That means if there is a black dot (on-centre) surrounded by white space (off surround) that you're looking at, some neurons respond at their highest firing rate.
• We model this with a neuron that takes inputs from the receptive field.
• It takes excitatory inputs from the centre,
• and inhibitory inputs from the surround.
• That's the visual input mechansim for our agents.
• The next level of processing does line, edge and corner detection.