Home | Contact Us | FAQ | Search & Site Map | Link to Us
Sign In | Join | Other 45 Sites in Network
Home
Discussion Groups
General
GeneralCardiologyVisionDentistryPharmacyLaboratoryNutritionAlternative
Diseases and Disorders
AIDSAlzheimer'sArthritisAsthmaCancerBreast CancerDiabetesEpilepsyGlaucomaHepatitisHerpesLupusProstate BPHProstate CancerProstatitisSinusitisTinnitus

Medical Forum / General / Vision / September 2006

Tip: Looking for answers? Try searching our database.

Ability to discriminate lightness values

Thread view: 
Enable EMail Alerts  Start New Thread
Thread rating: 
Johannes - 25 Sep 2006 10:54 GMT
Hi,

I read somewhere that due to visual interference the eye distinguishes
fewer luminance levels in dark areas than in light areas and that by
those means the number of luminance levels the eye can distinguish
decreases gradually from light to dark zones. Now does anybody know if
there is a certain proportion for that ability? If we´re able to
distinguish, say, ten times more values in areas of a given high
log/intensity than in those with a given low log/intensity?

Thanks for your input!
Johannes
Mike Tyner - 25 Sep 2006 15:39 GMT
> those means the number of luminance levels the eye
> can distinguish decreases gradually from light to dark
[quoted text clipped - 3 lines]
> given high log/intensity than in those with a given low
> log/intensity?

I don't know the answer, but you'd start by considering the two
photoreceptor systems separately. When you say "decreases gradually" it
sounds like you expect a smooth response curve. But it's unlikely the two
systems behave exactly the same.

It also helps to narrow down the type of stimulus for which you want an
answer. Contrast sensitivity, spatial acuity and color sensitivity all the
magnitude of JND's. For example, see "Purkinje shift".

http://www.engineering.uiowa.edu/~aip/Lectures/eye_phys_lecture.pdf

http://www.psych.ucsb.edu/~loomis/loomis_79.pdf

http://arapaho.nsuok.edu/~salmonto/Board_review.pdf

-MT
Mike Tyner - 25 Sep 2006 15:40 GMT
> Contrast sensitivity, spatial acuity and color sensitivity all the
> magnitude of JND's.

Should read "and color sensitivity all AFFECT the magnitude of JND's.

-MT
 
Sign In
Join
My Latest Posts
My Monitored Threads
My Blog
My Photo Gallery
My Profile
My Homepage

Start New Thread
Enable EMail Alerts
Rate this Thread



©2009 Advenet LLC   Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.