How we see

….if our eyes are as doors,

then the mind, it is clear,

ought to discern things better if the eyes

were taken out and removed, door-posts and all.

—————–On The Nature of Things, T L Carus.

• 1. few facts related with images and their processing

1. the eye’s retina contains 125 million lightsensitive cells, called photoreceptors. from these to the brain lead 800 thousand nerve fibres. that makes one fibre per 150 cells, so suggesting that even at retina level there is some information processing.

2. a sea of rays and just one pupil………would not they get mixed up, tangled??

3. the excitation threshold for rods involved in night vision is equivalent to the luminous intensity of a conventional candle viewed from a distance of 200 kilometers.

4. first book with title “optics” and explaining the working of eye was authored by Abu Ali Ibn-al-Haytham of Bagdad in 9th century. In this book he stated for the first time that every objects emanates rays and they reach our eye to form the object. The lens of eye then forms the object on retina. But he was not able to explain why images are formed inverted.

5. Kepler was the first scientist to understand path of rays in eye.

6. Lettvin, Maturana , McCulloch, Pitts found that in the eyes of frogs there are detectors which perceives moving objects and in response brain asks the frog to hunt, provided pray is small otherwise to take refuge. BUT if the pray is not moving, frog may die of hunger since the eyes can not register it.

7. People can distinguish about 40 shades of gray, so a 256-shade image looks like a photograph.”

8. We process 90% of all our information through eyes, rest 10% is by touch, taste, smell and sound. (ONLY 10% …… be careful what you are looking at :) )

yet to come…………………