Tetrachromats...

A tetrachromat is a person who has four kinds of cones in their retinas, instead of the three that the rest of us have.  Such a person would be able to see millions more colors than we could.  Scientists have long speculated that such people existed, but they've never actually found one.  Until now!

Mantis Shrimp...

You've probably never seen one of these shrimp, not even in an aquarium.  The Oatmeal explains why...and the answer is more interesting than you might think!

How Our Vision Really Works...

An excellent explication of the way our perception of color actually works, including both the physiology and our brain's influence.  The explanation is very accessible – you don't have to be a scientist to understand it.  What you were taught was almost certainly very different...

Optical Illusions...

It's a great one below, and there's another where that one came from.  I love illusions like this one that demonstrate so clearly the major role our brains have in visual perception...

A New Color...

I've posted before about the strange phenomenon of visible ultraviolet light.  This was discovered in WWII when cataract patients serving off the coast of Nazi-occupied Europe reported that they could see the glow of German night troops using ultraviolet lights.  The German troops were equipped with an early form of night vision equipment that the Allies couldn't duplicate until near the end of the war.  But with the fortuitous discovery that cataract patients could see the lights, the Allies were able to detect when the German night troops were using this gear.

The cataract surgery back then involved complete removal of the eye's inner crystalline lens.  To compensate, the patients had to wear “Coke bottle” lenses in their glasses.  The natural crystalinne lense is opaque to ultraviolet light, but the external glass lenses were not – so for the first time in their lives, these patients had ultraviolet light impinging on their retinas.

Now a much more modern form of cataract surgery, in which the natural crystalline lens is replaced, has produced the same effect – because the replacement lens is made of material that is transparent to ultraviolet light.

Your Visual System...

The human visual system is far more amazing that most people realize.  We can't even come close with modern digital cameras and video processing.  For example: how many megapixels do our eyes have?  The question isn't entirely answerable, but at a rough approximation: 576 megapixels.  My new camera has 12 megapixels.

Much, much more here, by Dr. Roger Clark...

Color Vision...

The most accessible explanation of human color vision and perception I've seen.  Even so, it doesn't shy from the mysteries that most texts avoid...

Bugs Bearing Bifocals – Awesome!

Read all about it.

I'm Envious...

Of these animals who can see five different primary colors, instead of the three that I can see.  Which animals are those?  Chickens.

Causes of Myopia, and Possible Prevention...

Interesting article in New Scientist...