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Message: <blockquote data-quote="typo" data-source="post: 3436633" data-attributes="member: 83808">Adhoc,As I said, the psychological side I struggle to get to grips with but I'll have a go at explaining some of what I've been gleaned. I think most of us assume that we have three colour receptors in the eye, and three colour channels carry the information along to the optic nerve to the visual centres of the brain and we see an faithfull reproduction of the original view. It really doesn't happen that way. The image processing starts in the retina and goes though a number of intermediate filtering processes on route. Just one of the numerous processing routes is the colour opponent pathway which is nicely summaried in this blog.<a href="http://www.scribblelive.com/blog/2011/12/07/the-use-of-yellow-in-data-design/" target="_blank">http://www.scribblelive.com/blog/2011/12/07/the-use-of-yellow-in-data-design/</a>Anyway, the signal from the reptors is already heavily modified before it reaches the brain. It then goes through a number of stages where various levels of information are extracted. Depending on what information is required for you current activity, much of the time this partial, selective information will form the basis of what we 'see'. The rest is simply made up by the brain based on memory and expectations amongst other things to produce a relatively complete visual image. In reality, most of the time it's just the product of the brain's version of photoshopping.One filtering process I found interesting is the difference between how we analyse sharpness vs. acuity or visual resolution. Sharpness is a low definition but fast processing method. It allows us to rapidly identify the major feature of the view so we are able to do things like run over a rough terrain. The processing time for sharpness is in the tens of milliseconds. It takes a lot longer for the brain to process the detail required to see the finest detail, usualy in the 100s of milliseconds. In terms of the level of visual detail there is something like a hundred fold difference per unit area. So what do individuals actually mean when the comment on sharpness?Because all these pathways and levels are processing are entirey subconcious it can be extremely difficult to figure out whether to believe what we 'see', or really it's a bizarre construct of our imagination. Knowing this I find it takes quite a bit of concentrated effort to even begin sorting out the fact from fiction.There is an awful lot of stuff I really don't understand about what the brain actually does even within the limited scope of comparing colour bias of binoculars, but from my tiny bit of knowledge I'd urge all to be beware of believing what they think they see.David</blockquote>

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