Resolving Power of Retina

[T3D Rolf Henkel <henkel@xxxxxxxxxxxxxxxxxxxx>]

> John B. asks about resolving power of retina..e.g. rods and cones
> like ccd sensor, sort of limited?

I had a quick look into a book on my desk (G. Hauske, "Systemtheorie der
visuellen Wahrnehmung [Theory of Visual Perception]", Teubner 1994,
Stuttgart):

Humans have a fovea, so resolving power drops of rather fast away from
the fixation point (that's the reason for saccades). In the center of
the fovea, we have normally a resolving power of 1 minute (which
transfers to about 3mm at 10m distance), which can be increased to 0.5
minutes by high contrast scenes. In addition, there is the phenomena of
hyper-acuity: for example, the alignment of two lines, slightly shifted
against each other, can be judged much better: here, the resolution goes
down to 5-20 seconds. Interestingly, stereo vision works always with
hyper-acuity;  our visual system generally estimates relative shifts
between the left and right retinal images which are far smaller than the
spacing of receptors in the retina! 

Rolf Henkel

Institute of Theoretical Neurophysics, University Bremen, Germany
-----------------------------------------------------------------
Email:	henkel@xxxxxxxxxxxxxxxxxxxxxxxxx
URL:	http://axon.physik.uni-bremen.de/~rdh/research
-----------------------------------------------------------------


------------------------------