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Author Topic: What Is The After Image After A Bright Light Is Shone In Your Eyes ?  (Read 3802 times)

Offline neilep

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Dearest Eyeologists,

As a sheepy I of course have eyes. Eyes are my all time favourite pair of body organs that enable me to see. Well done to the bloke who invented eyes !!

Look here's a human eye :



A Human Eye Earlier Today Inserted Here Cos CliffordK Is Super !!


Erhmm..I hope there is an image of an eye here....as the Attachment section does not have the ' upload' button anymore !!!!!


Anyway,

If ewe shine a bright light in your eyes and then close your eyes ewe can clearly see an after image yes ?...almost like a negative.....This " negative " also changes colour a few times before eventually dissipating !


Why's that then ?..What Is The After Image and Why Does It Go Through A Variety Of Colour Changes ?


Thanks


Hugs and shmishes


mwah mwah mwah

Neil
Don't forget to dot your I's
xxxxxxxxxxxxxxxxxxxxxx
« Last Edit: 01/01/2012 15:47:49 by neilep »


 

Offline SeanB

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Simple answer for the Sheepie is that vision is a chemical reaction. The light bleaches a chemical produced in the cells in the retina, and this reaction is then translated and sent via the optic nerve to the brain, where we interpret it as light. If a bright light is shone in, then all of the chemical is reacted away, and this will take some time to be remade. Thus for that time the area affected sends no signals, even if light is there, and appears dark. That is the dark afterimage, and the strange colours are as a result of the various colours having different chemicals that they react with, and they are depleted and rebuilt at different rates, thus giving the coloured fringes around the dark spot.

You want more somebody else probably has it, or "Tag va Google".

 

Offline neilep

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Simple answer for the Sheepie is that vision is a chemical reaction. The light bleaches a chemical produced in the cells in the retina, and this reaction is then translated and sent via the optic nerve to the brain, where we interpret it as light. If a bright light is shone in, then all of the chemical is reacted away, and this will take some time to be remade. Thus for that time the area affected sends no signals, even if light is there, and appears dark. That is the dark afterimage, and the strange colours are as a result of the various colours having different chemicals that they react with, and they are depleted and rebuilt at different rates, thus giving the coloured fringes around the dark spot.

You want more somebody else probably has it, or "Tag va Google".



Thank ewe very much Sean....Eye consider myself enlEYEtegned !  *groan*......
 

Offline RD

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The human eye is not equally sensitive to all colours,
In bright light it is is most sensitive to green light ... https://en.wikipedia.org/wiki/Luminosity_function

(Maybe due to the peak colour of sunlight being  yellow-green )  ...

Quote
 [the Sunís] visible radiation is most intense in the yellow-green portion of the spectrum
https://en.wikipedia.org/wiki/Sun

The the afterimage of a sunlit (of flash-lit image) is the compliment of green, magenta , (like the bit of the CD near the top of your ear) ...



[ Nicely composed image BTW, with the recurring concentric motifs on the diagonal, both close to the intersection of thirds, just needed a bit of shadow recovery IMO]   
« Last Edit: 02/01/2012 13:56:20 by RD »
 

Offline neilep

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The human eye is not equally sensitive to all colours,
In bright light it is is most sensitive to green light ... https://en.wikipedia.org/wiki/Luminosity_function

(Maybe due to the peak colour of sunlight being  yellow-green )  ...

Quote
 [the Sunís] visible radiation is most intense in the yellow-green portion of the spectrum
https://en.wikipedia.org/wiki/Sun

The the afterimage of a sunlit (of flash-lit image) is the compliment of green, magenta , (like the bit of the CD near the top of your ear) ...



[ Nicely composed image BTW, with the recurring concentric motifs on the diagonal, both close to the intersection of thirds, just needed a bit of shadow recovery IMO]   


Thank ewe RD for your comments and links !....excellentay !.....with all this info I am truly spoiled !

...and thanks for the comment about the actual photo too !...It's all very subjective of course but I do prefer what ewe have done to the colour of the cd....though I feel the face looks like it needs some moisturiser now...whereas the original was more discrete and smooth !....I do appreciate your critique !

 

Offline RD

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I have moisturiser (a.k.a. wavelet denoise) ...





 

Offline neilep

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Thanks RD...as smooth as my bot-bot now !  ;D
 

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