Lecture 1: Introduction to Biological Vision - Vision Research ...

• Functions of the retina– discrete image samplingRetina• Why aren't the receptors packed closer together? Physical wave guide limits?– automatic gain control• Retina codes contrast, not intensity– band-pass spatial filtering (“lateral inhibition”)• I.e. neither slow nor very rapid spatial changes in intensity are seen– economical coding (e.g. predictive coding)– front-end for edge detection– band-pass temporal filtering• I.e. neither slow nor very rapid temporal changes are seen– economical coding– front-end for motion measurement– color coding• (some animals have motion selective cells in retina, but not cats andprimates)• remove correlations from cone signals• front-end for color constancy mechanismsR L(x, y, t) L avgL avgW(x,y)R ~ W(x,y)*L(x,y)Wednesday, August 29, 12