Functional stages

by Dan-Eric Nilsson

• Stage 1: Monitoring intensity of light: single photoreceptor. "Brightness indicator"
• Stage 2: Light direction: photoreceptor that is blocked. "Pixel periscope"
• Stage 3: Multiple light sources: groups of photoreceptors. "2D Images"
• Stage 4: Focused, precise light: lens. "Shape-detection"