Our Vision

Eye

0Wikipedia-logo-en-bigEyes are the organs of vision. They detect light and convert it into electro-chemical impulses in neurons. In higher organisms, the eye is a complex optical system which collects light from the surrounding environment, regulates its intensity through a diaphragm, focuses it through an adjustable assembly of lenses to form an image, converts this image into a set of electrical signals, and transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. Eyes with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system. Image-resolving eyes are present in molluscs, chordates and arthropods.

Human eye.

Human eye.

vía Eye | Wikipedia.

13 Things You Didn’t Know About Eyes


vía 13 Things You Didn’t Know About Eyes | YouTube.

CAMERAS VS. THE HUMAN EYE

Our eyes are able to look around a scene and dynamically adjust based on subject matter, whereas cameras capture a single still image. This trait accounts for many of our commonly understood advantages over cameras. For example, our eyes can compensate as we focus on regions of varying brightness, can look around to encompass a broader angle of view, or can alternately focus on objects at a variety of distances.
However, the end result is akin to a video camera — not a stills camera — that compiles relevant snapshots to form a mental image. A quick glance by our eyes might be a fairer comparison, but ultimately the uniqueness of our visual system is unavoidable because:
What we really see is our mind’s reconstruction of objects based on input provided by the eyes — not the actual light received by our eyes.

DM
vía CAMERAS VS. THE HUMAN EYE | CAMBRIDGEinCOLOUR.

Visual acuity

0Wikipedia-logo-en-bigVisual acuity (VA) is acuteness or clearness of vision. It depends on optical and neural factors, i.e., (i) the sharpness of the retinal focus within the eye, (ii) the intactness and functioning of the retina, and (iii) the sensitivity of the interpretative faculty of the brain.
A common cause of low visual acuity is refractive error (ametropia), or errors in how the light is refracted in the eyeball. Causes of refractive errors include aberrations in the shape of the eyeball, the shape of the cornea, and reduced flexibility of the lens. In the case of pseudomyopia, the aberrations are caused by muscle spasms. Too high or too low refractive error (in relation to the length of the eyeball) is the cause of nearsightedness (myopia) or farsightedness (hyperopia) (normal refractive status is referred to as emmetropia). Other optical causes are astigmatism or more complex corneal irregularities. These anomalies can mostly be corrected by optical means (such as eyeglasses, contact lenses, laser surgery, etc.).
Neural factors that limit acuity are located in the retina or the brain (or the pathway leading there). Examples for the first are a detached retina and macular degeneration, to name just two. A common impairment amblyopia caused by incorrect nerve pathway function connecting eye with brain is involved. In some cases, low visual acuity is caused by brain damage, such as from traumatic brain injury or stroke. When optical factors are corrected for, acuity can be considered a measure of neural well-functioning.

A typical Snellen chart that is frequently used for visual acuity testing.

A typical Snellen chart that is frequently used for visual acuity testing.

via Visual acuity | Wikipedia

What Is The Resolution Of The Eye?


vía What Is The Resolution Of The Eye? | YouTube.

HUMAN EYESIGHT & 4K VIEWING

With photography, fine art prints typically utilize 300 pixels per inch, which requires a viewing distance of one foot for someone with 20/20 vision to resolve. However, pixels do not always have to be this densely packed. With enlargements, the standard rule of thumb is that these will be viewed at a distance similar to the diagonal print dimension. This causes the print to encompass an angle of view spanning about 50° in its longest dimension…

The Health and Nutrition Examination Survey of 1972 demonstrated that 72.8 percent of the civilian non-institutionalized population 4-74 years of age in the United States has distance visual acuity of at least 20/20 in their better eye “with usual correction” (using glasses and other visual aids).

The Health and Nutrition Examination Survey of 1972 demonstrated that 72.8 percent of the civilian non-institutionalized population 4-74 years of age in the United States has distance visual acuity of at least 20/20 in their better eye “with usual correction” (using glasses and other visual aids).

via HUMAN EYESIGHT & 4K VIEWING | red.com.

As TV Resolution Increases, Your Eyes May Be the Limit

By Justin Bachman January 16, 2014

  • TV’s Future

With 3D fading into oblivion, the big news in televisions these days is ultra-high definition, TV makers’ quest to quadruple the resolution of the average high-def flat panel found in most U.S. homes. Called 4K resolution, it can be stunning, with deeper colors and a picture that many people often equate to “real life.” The new higher-resolution is expected to expand slowly in 2014. Netflix (NFLX) plans to stream some content at 4K resolution this year, and Amazon (AMZN) announced it will shoot all of its original series in 4K ultra-HD starting this year.
Gorgeous image or not, the question arises: At what point do the capabilities of the technology outpace those of our eyes? Farhad Manjoo, writing in the Wall Street Journal, declared that we’re almost there: “Nobody’s eyes are good enough to appreciate resolution above 4K.”

DM
vía As TV Resolution Increases, Your Eyes May Be the Limit | BloombergBusiness.


DM

Good looking: 6 surprising ways to improve your eyesight

Not many of us have perfect eyesight, and we will develop problems as we get older. Until recently, glasses or contact lenses were just about the only options.

But as we’ve learned more about the eye, we’ve come up with surprising ways to preserve or enhance vision, from changing what you eat to software that lets you read your smartphone without reading glasses.

(Image: ERproductions/Blend Images/Corbis)

(Image: ERproductions/Blend Images/Corbis)

vía Good looking: 6 surprising ways to improve your eyesight | New Scientist.

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