Retinal Prosthesis Dissertation - Student Home Pages

Eye
Neural
Network –
Artificial
Retina
Lens
Optic nerve
Figure 7 replacing the retina
Within the visible spectrum extending from extreme red; 760.6nm, to extreme violet;
393.4 nm lie the four psychological primary colours of Ewald Hering’s theory[12].
So called because it does not appear to the human eye that they can be separated into
any more basic colours e.g. bluish-green or yellowish-green can be imagined but not
greenish-red or a bluish-yellow. The eye has three cone receptors conventionally
described as red, green and blue cones following Thomas Young’s trichromacy
theory[12]. The red (long γ) cone has pigments which absorb maximally at 565nm,
green cone (middle γ) absorbing maximally at 530nm and blue cone (short γ)
absorbing maximally at 420nm[12]. Therefore the retina converts the four primary
colours (red (620–750 nm), green (495–570 nm), blue (450–475 nm) and yellow
(570–590 nm)) to which it is sensitive into the three primary colours red (R), green
(G) and blue (B) to which the optic nerve is sensitive.
2.2 Neural network representation
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