Slides on Vision

Blue / YellowBipolar Cell

Green / RedBipolar Cell+− +−

+− − + −/+Opponent – Process

Theory

Blue Green Red Yellow

+-

On center

off surround

Center-Surround Cells

+- -

G

+-

Mild excitation

Mild inhibition

Maximal excitation

Maximal inhibition

Minimal effect

+-

+-

+-

+-

Darker

Lighter

Mach Bands &The Hermann Grid

+-A

+-B

+-C

+-D

B is more inhibited than A and will appear darker

C is less inhibited

than D and will appear lighter

Explaining Mach Bands

Small foveal

receptive fields

Largeperipheralreceptive

fields

More light falls on inhibitory surroundwhich leads to seeing a dark spot

+---

-+ --

Explaining The Hermann Grid