[vsnet-chat 20] Purkynje (Purkinje) effect -Reply

[Berto Monard <lagmonar@csir.co.za>]

Hi,

I believe Seiichiro is a bit premature with his thanks. Looking
through the postings I read a lot on Purkinje but nothing
substantial on the P effect. Is there someone who can quote from
the proper text books?
I have a vague knowledge about the P effect but not enough to
actually write in detail about it. I take the risk anyhow. 
The Purkinje effect has to do with the shift from photopic to
scotopic vision during the darkening of the viewing field ie the
shift from rod to cone vision. What it accounts to is that in a
bright environment (daylight or well lit targets), we (unless we are
color deficient) are relatively more sensitive to red colors and
gradually get more sensitive to blue when we adapt to dark
conditions. The specific properties of vision wrt geometry and off
line viewing of the different types of vision are supplementary
effects.


Regards,

Berto Monard 
from the South

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