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Why we see black colour when we close our eyes

Why we see black colour when we close our eyes



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Why is it neccessary that if there is no light then everythimg is black and when we close our eyes we see everthing black usually when we are in black room??


The mechanism of sight is as follows (ref. 1). This was shown in the 1100s by Ibn al-Haytham (ref. 2), except the 4th step which may have been proposed by Galen in the 100s (ref. 3).

  1. Light comes from a light source
  2. The light then hits an object
  3. The light then bounces off the object into your eye
  4. Your eye sends a signal to your brain. Your brain then figures out what you're seeing

So in order for us to see, you need light getting into your eye (step 3). If you're in a dark room you have no light source, so no sight (no step 1). If you shut your eyes, you're stopping light from getting into your eye (no step 3). When there's no light getting to your eye, the eye tells this to your brain. So your brain just sees black (the absence of light).

References

  1. Duree, G. (2011). Optics for Dummies. p. 67.

  2. Adamson, Peter. (7 July 2016). Philosophy in the Islamic World: A History of Philosophy Without Any Gaps. p. 77.

  3. Reeves, C. and Taylor, D. (2004). A history of the optic nerve and its diseases. p. 1097.


What is the color which we see when we close our eyes. (its not black, its something else)

The colour which we see when we close our eyes is called Eigengrau which is different from black.

It happens due to a phosphene that allows us to block the natural light and get into a dark colour called Eigengrau .

Supplementary information :

  • The word Eigengrau is also a name of a music recording company found by JacobRuttenberg.

Explanation:

It is called Eigengrau . The difference between them is their hex values.

Eigengrau (German for "intrinsic gray", lit. 'own gray' also called Eigenlicht (Dutch and German for "own light"), dark light, or brain gray, is the uniform dark gray background that many people report seeing in the absence of light. The term Eigenlicht dates back to the nineteenth century,but has rarely been used in recent scientific publications. Common scientific terms for the phenomenon include "visual noise" or "background adaptation". These terms arise due to the perception of an ever-changing field of tiny black and white dots seen in the phenomenon.


Artificially Induced Phosphenes

A common demonstration by professors in college is to have their students gently press on their eyeball in the dark. When done correctly, a football shaped white patch will be seen just off center of your field of vision. What you’re seeing is a bundle of axons attached to your fovea becoming active.

Those particular axons are a little thicker than your retina so the pressure from your finger pushes them onto the rods and cones at the back of your eye. This creates a phosphene. While it’s an interesting demonstration, we do not recommend attempting this without the assistance of a medical professional.


What Do We See When Our Eyes Are Closed?

Closing your eyes can be trippy, with a kaleidoscope of shapes and colors visible behind shut lids. What are we seeing behind closed eyes? Ivan Schwab, professor of ophthalmology at University of California, Davis, and a clinical spokesperson for the American Academy of Ophthalmology, explains.

Eyes Wide Shut

Those who sleep with blindfolds on can attest that, even in the absence of any visible light, the visual field fires up. “It’s like a non-drug hallucination,” says Dr. Schwab, who wrote “Evolution’s Witness: How Eyes Evolved,” explaining how vision has changed across nearly four billion years.

When the eyelids are closed but without a blindfold, most people can see wispy clouds, moving specks of light, geometric shapes, flashes of white, snow and a range of colors, he says. “Kids love doing this, because it’s fun, and they are curious.”

The pathway of vision is from the eyes to the brain, Dr. Schwab explains. If you apply pressure to the eyeball when the eye is closed, you may see an explosion of color. “Photoreceptors, cells in the retina that detect light, don’t know the difference between stimuli, and only have one option for reacting—sending a message to the brain,” Dr. Schwab says. “Pressure will cause them to act the same as if they were being stimulated by light.”

A similar effect can be created under special conditions in a laboratory using a magnetic source placed behind the head, where the visual cortex lies.


The new black – and the old

When sculptor Anish Kapoor reached an exclusive agreement with the manufacturers of Vantablack – a substance called "the blackest black in the world", capable of absorbing 99.96 per cent of light – it sparked outrage among fellow artists. "This black is like dynamite in the art world," huffed painter Christian Furr. "It isn't right that it belongs to one man."

Renoir called it the "queen of colours". Henri Matisse, lauded as a supreme colourist, confessed that when he didn't know what colour to put down "I put down black".

But black retains heat as well as light, making its use in construction problematic. While black-and-white buildings – like houses of the Tudor period or the Duomo in Florence – always look smart and elegant, all-black buildings are a relative rarity.

Some are black through age alone, like the 900-year-old wooden church at Urnes in Norway, built at the time the Norse gods stood alongside the Christian trinity. In Scandinavia, farm buildings were preserved with pitch or tar, a method used by Vikings to waterproof their boats. In Salem, Massachusetts, Puritan pioneers adopted black as a symbol of their purity and austerity.

Japan has shou sugi ban – a technique of charring which gives a smoky chiaroscuro effect to the natural grain. The Music Box residence in Portland, Oregon, designed for two musicians, uses timber treated in this way to create a 600-square-metre house with room enough for a rehearsal studio.

Budakirkja Church, Iceland 1848. Weatherproofed with black pitch, just as a Viking ship would have been, this church sits in splendid isolation above a vast lava field on the country's west coast. Alamy

New materials such as vulcanised rubber, black concrete or sprayed polyurethane have revolutionised architecture's use of black. Glass or polished steel give a glossy sheen to black's depths. A building like the Museum of Contemporary Art in Cleveland reflects the surrounding cityscape, but hides itself, giving full rein to an appreciation of its gravity-defying geometry.

Contemporary urban Japanese homes are fascinating in their reductionism. Occupying a tiny site in a provincial town, the LIFT house turns its back on the street in an almost total escape from the world, impermeable to passers-by. There's a sense almost of menace in the way that the house's weight hangs forward, encasing a light-filled terrace behind black-painted slats.

Black manages to be several things at once: enigmatic and rare, rich, humble, discreet, provocative. Because of its versatility, we can forget how primal and powerful it really is.

Black: Architecture in Monochrome, by Phaidon Editors with an introduction by Stella Paul. Phaidon, $59.95.

Domo Dom House, Poland, 2013. This tiny zinc-clad house in Krakow – just a dining room, kitchen, bathroom and small attic bedroom – curves up over a garage, leaving the maximum amount of garden space. Phaidon

LIFT house, Sendai Japan 2011. This wooden family residence in provincial Japan cantilevers out over a car space and hides its white interior, central courtyard and louvered balcony behind a Darth Vader-style mask. Altaimage


SENSE MAKING

An important factor when considering visual perception is that as light enters our eyes it does not have any properties that allow it to carry information about the world of objects and the other things, we so easily recognise around us. The only type of information carried by light that our eyes can register is related to properties such as wavelength, frequency and intensity. Therefore, the sense-making process gathers nothing more from photosensitive cells in the retina other than flickering patterns of light.

But if this is the case then how do we make sense of the world? Let’s look at the basics of sense-making in more detail!

Most people are familiar with the idea that colours do not have an external objective existence. This understanding has a grounding in physics. Light is composed of energy at different wavelengths and our eyes respond to one small band of those wavelengths within the electromagnetic spectrum. Anatomical studies have in turn revealed the existence and function of the light receptors in the retina of our eyes that respond to light.

So, there is no red out there in the world. What we call red is our visual system’s interpretation of what we are looking at. Our visual system constructs the experience of red from the data provided by our eyes. Despite all this, when I see a car, the fact that it is red is an indisputably accurate description of my observation. Somehow the redness of the car is a simple fact.

Neuroscience is currently trying to explain how this happens. What we know is that our visual system favours fast reaction times and rapid interpretation and there is nothing to be gained from the brain revealing its inner workings in the course of everyday experience. To the contrary, it specialises in providing us with just the information we need and in precisely the form we need it. We receive no information about how our eyes and brain gather or process information. The car just looks red and if we see a tiger then hopefully there is still time to run away as fast as we can!


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Colour Assimilation

Previously we discovered that when a large area of one colour is adjacent to, or surrounded by, a large area of another colour, the colour differences seem more pronounced – Simultaneous Contrast at work. The reverse occurs when small areas of colour are interspersed with small areas of another colour, the resulting illusion being that the colours appear more alike. This effect is known as Colour Assimilation (also referred to as spreading effect or Von Bezold effect).

When small strips of red are interspersed with small strips of blue (bottom), the colours look more alike than they actually are (top). Colour Assimilation causes the red to appear more blue and the blue to appear more red.

Red stripes, when alternated with black stripes, appear darker (top) whereas when alternated with white stripes, appear lighter (bottom). The eye mixes the value of red with the values of the black and white respectively, thus darkening/lightening it.

We experience this often in the garden – it is most commonly observed in flowers with more than one colour (especially those with detailed colour patterns), or leaves with small variegations. For example, a flower that has petals of one colour, sepals of another, stamens of yet another, intricate veins, and contrasting eye zones – unless viewed up close, our visual system will interpret the colours as more alike and begin to blend them.

The flower of Hemerocallis ‘Strawberry Candy’ presents numerous colours, the detail of which is mostly lost when seen from even a short distance away. The eye has mixed the various colours together and averaged their hue, value and saturation. Photos: Sue Gaviller

Another example – leaves that are striped green and white appear lighter because the eye mixes the medium value of the green with the high value of the white, thus producing the illusion of lighter green leaves.

The striped foliage of Miscanthus sinensis ‘Variegatus’ appears soft pastel green when viewed from a few feet away. When viewed up close, the colour detail becomes apparent. Photos: Sue Gaviller

Variegated leaves consisting of larger blocks of colour, say a green Hosta with white or cream coloured margins, won’t exhibit this effect because the larger area of colour allows the eye to accurately discern the edges and differentiate the colours.

The image on the left illustrates this – the Hosta at the bottom of the photo shows no colour blending, Euonymus at the top exhibits some, and Lamiastrum in the centre shows considerable assimilation, such that the leaves appear very pale gray-green.

Colour Assimilation will be greater when plants are seen from a distance – as the eye fails to distinguish stripes, margins, veins, stamens, eyes, throats and other leaf or flower features, the colours will blend together, averaging the hue, value and saturation of each colour as the viewing distance lengthens. Recognizing how and when this happens can be helpful in editing our plant choices for maximum colour satisfaction.

The inflorescence of Spanish Lavender (Lavandula stoechas) consists of light purple bracts atop darker purple flowers. Note how the dark coloured flowers begin to appear lighter and the light coloured bracts begin to appear darker when observed from farther away. Eventually, with further distance, they appear as all one medium value purple. Photos: Sue Gaviller


Beyond Colour: Those Bloody Reds

In an article written long before directing his first feature, Antonioni recognized colour as a powerful and partly autonomous element of film language, “a changing of tone being caught up and carried over elsewhere, in play of tones created for example by the passage of clouds over the valley in John Ford’s Stagecoach.” These were the 1940s: Technicolor was in full swing, with deliberately over-saturated colour schemes typified by The Wizard of Oz and Gone with the Wind and an exhibitionist attitude towards their use. Antonioni called for control which would allow colour to transcend its function as décor, and participate in shaping “the psychological movement, the drama”.

Years later, in an interview for Cahiers du Cinema regarding the amount of blood in his film Pierrot le Fou, Godard insisted, “Not blood, red.” His treatment of red denounced the nature of violence and cruelty but, most importantly, linked cinematic instances into a fluid syntax of after-images that break away from linear narrative.

From the early days of cinema when each frame was painstakingly hand-tinted to create a recognizable filmic world, the emancipation of colour has unleashed a powerful visual tool which can serve as a syntactic generator of continuity and a semantic foundation for a film’s symbolic quality. Perhaps more than any other colour, red has established itself as a visual fuel often used to delineate different or contrasting realities. Besides its purely abstract dimension, red creates an arc of symbolic possibilities, from visceral associations to blood and the corporeal, to concepts of power, hatred, lust and the spiritual. Hot colours of latent violence in Spike Lee’s Do the Right Thing, the alienating red in Antonioni’s Red Desert, and the red-eyed supercomputer gone rogue all showcase red’s formal and symbolic polyvalency, as a photo developer that changes its appearance by reacting with different chemicals.

Cries and Whispers(1972)

Cries And Whispers (1973), Ingmar Bergman

There is hardly any blood in Bergman’s Cries and Whispers but by the end of the film, its distinctive red is carved into our eye’s retina as “the colour we see when we close our eyes against a bright light.” The highly-stylized film is bathed in hyper-saturated reds set against the drained faces of four women (three sisters and a maid) bound together by the expectance of death. Photographed by Bergman’s long term cinematographer Sven Nykvist, the walls, heavy curtains and rugs of the old mansion are given an oneiric quality drenched in reds which, in Bergman’s own words, represents the inside of the soul.

Visceral connection of colour to the flesh-rotting disease that has struck one of the sisters plays upon the film’s highly stylized production design. As the camera navigates the claustrophobic hallways and rooms heavily saturated with the tyrannical red, horrid screams of agony, repressed sexuality and hate, colour assumes an anthropomorphic character: it is an anatomic spatialization of angst. The interiority of the women is physicalized to the extreme as a pulsating labyrinth of caverns hypersensitive to touch. Somewhere between master-shots of sisters sitting in silence and violent close-ups, red ceases to be a colour and becomes a spatial synesthetic device which confuses whispers with kisses and screams with touches.

Europa(1991)

Barbara Sukowa in Lars von Trier’s Europa (1991)

A different visual mechanism is at work in Lars von Trier’s Europa. Part of the director’s trilogy on the social and cultural schisms of post-war Europe, the film establishes a visual dichotomy between the achromatic portrayal of our hero’s journey through a war-torn Berlin and visual crescendos in colour marking realer-than-reality moments of emotional tension. Most importantly, colour is used as a rhythmic element that establishes the pace of the film.

As the black-and-white film unrolls into the seemingly endless night of a destroyed Germany, a US marine of German descent, played by Jean-Marc Barr, arrives in Berlin to help rebuild the country and “show some kindness” to the German people. His naive resolve to stay neutral disintegrates as he finds himself amidst a pro-Nazi terrorist conspiracy, one that reveals all the ruthlessness of having to pick sides.

Although Von Trier’s distinctive tendency to experiment with technical possibilities of the medium often results in overly formalistic approach to filmmaking, in Europa he is right on the mark. Here colour is a visual cue that enters the frame exactly when needed: to show Barbara Sukova’s radiant complexion and succulent lips or bring in an enriching layer of truthfulness as the main character encounters a moral dilemma. Masterfully shot by cinematographer Henning Bendtsen, the scene of a suicidal shaving with red droplets of blood spreading through the black-and-white rippling of water resembles a distant dream being intruded upon by reality. The sight of reds, together with Max von Sydow’s hypnotic voice which leads the viewer through the psychogeography of Europa, counts the slowing pulse of the film, as its hero fights for his last breath of air.

Don’t Look Now(1973)

Don’t Look Now (1973), Nicolas Roeg

’My sister hates it,’ says one of the characters about Venice, in Nicolas Roeg’s macabre Don’t Look Now. She says it’s like a city in aspic, wrapped over from a dinner party, where all the guests are dead or gone.” Roeg’s Venice is far removed from its canonized look as the ultimate romantic setting. Its canals and haunting architecture are soaked in earthy tones, a stage set for the appearance of red, as it traverses different chronological and spatial planes.

Colour is treated as the recurring element that tracks the narrative arc of film as two grieving parents, played by Donald Sutherland and Julie Christie, leave for Venice after their daughter drowns in an estate pond in England. The couple meet two elderly women, one of whom possesses the ‘second sight’ and claims to see the dead child.

The director uses colour in a symbolic manner loosely knit into a piece that flirts with the spiritual and the religious. The red stain on the slide, the little girl’s red hood floating in the water, the wife’s red boots, the father’s red scarf and finally, the muted reds of decaying rooftops and moldy walls of Venice paint a picture of a world haunted by the supernatural. Roeg, cinematographer turned director, gives an abundance of references, but doesn’t reveal much about their meaning. He breaks the linear narrative form by inserting twitchy tracking shots, flashbacks, flash-forwards, and zooms but uses colour to keep the film’s structural integrity. He flirts with the concepts of time and alternate realities, masterfully pioneered by Krzysztof Kieslowski, but the meaning behind these remains oblique. What we’re left with are moments of violence foreshadowed by the appearance of the red hood.

Donald Sutherland in Nicolas Roeg’s Don’t Look Now (1973)


Intoxicated by colour

Who can resist colour! Colour provides a metaphor for pleasure, health and vitality. Spring is colourful winter is grey. The world of the child is supposedly bright with innocent colours, compared to the dull tones of old age and decay.

But don’t efflorescences of colour also indicate contamination, virulence and toxicity?

Apparently the human visual system responds to light as electromagnetic radiation in the approximate frequency range 400 to 800 terahertz (million million cycles per second). Photosensors in the eye are specialised to respond to three different bands from within this spectrum, each registering as a colour: red, green and blue. The combining of the three visual responses makes up the visible spectrum.

This intricate adaptation indicates close coupling between organism and environment. The eye and brain convert what in measurable terms is just a continuum into a series of colour bandings that excite and stir varied meanings and associations. Though individual responses to colour vary, anyone with full sight recognises the difference between red and yellow, and their associations.

From a biological point of view, the human sensitivity to light and colour depends on a finely tuned combination of sensory processes that (i) biology can support efficiently, (ii) are calibrated to the particular properties of light on the planet, and (iii) enable us to apprehend features in the environment important for survival, such as identifying foods, warnings, and probably a mate.

Colour is undoubtedly complicit in pleasurable experiences, but what of colour-filled moods more sombre, violent or portentous? As was known to the ancients, many synthetic colouring agents turn out to be toxic, as is their means of manufacture and fixing. Here are some images of the photogenically Medieval but notoriously noxious open pits for dyeing leather in Fez, Morocco.

Colour associates with the properties of toxic chemicals, poisons and drugs. In Phaedrus Plato recounts a story in which the art of writing is equated to the use of a drug. Having the facility to write things down intoxicates the writer and manufactures a sense of intellectual confidence and well-being. In his analysis of Plato on this point Jacques Derrida explains that the word Plato uses for “drug” (pharmakon) has many associations. It’s the kind of coloured makeup applied to corpses before burial. Drugs are also both a means of curing illness and of killing the patient. Cure and killing, panacea and poison, treatment and toxin, vibrant and noxious chromatism, are not so far apart — properties associated with drugs, chemicals, poisons and colours (and writing of course, but that’s another story).

Early practitioners of the medical arts, eg Galen (129-200 AD), identified the need to keep the body’s humours in balance, ideas that spill into colour theory. In his Art of Color the Bauhaus theorist Johannes Itten observed:

“If we gaze for some time at a green square and then close our eyes, we see, as an after image, a red square. If we look at a red square, the after image is a green square. This experiment may be repeated with any color, and the after image always turns out to be of the complementary color. The eye posits the complementary color it seeks to restore equilibrium of itself.” (p.21)

It seems as though colour pertains to harmonious balance, but also imbalance. Itten explains how the customers of a fabric manufacturer complained that a black thread on a particular red background looked green, which was unacceptable to them. Itten says the solution would have been to dye the thread brown instead of black. Then it would have had the appearance of black in that context. In certain combinations colour harmony becomes unbalanced, and colours need correcting.

Colour combinations that signal alarm, that certain organisms use to deter predators, seem to deploy what Itten identifies as simultaneous contrast, created when two colours are juxtaposed that are not exactly the complement of each other.

Itten describes several such colour combinations, one of which involves red-violet and red-orange on a green background. The effect of the simultaneous contrast is a clash, “an irritated simultaneous rubescence” (p.89). He could be describing an efflorescent rash. I’ve tried to replicate the colour combination illustrated in his book here. The colours are not particularly arresting in isolation, but when combined, the simultaneous contrast effects cause oscillations — and even nausea in certain situations.

Printers ink and film colour fade. Already our library’s 1961 edition of The Art of Color is perceptibly muted. Recall the graphic aura of the 1960s and 70s, when colour was “rediscovered.” Think of rainbows, flower power and experimentation with recreational drugs. It’s now faded, but I recall at the time the record covers were vivid.

Thanks to back-lit LCD displays we have never been so exposed to the dynamic control of colour, and in full intensity. There are even smartphone apps for false fading (Instagram).

Colour vibrancy, so appealing to children and the child-like moments in adulthood, derives much of its impact from simultaneous contrasts, jarringly rubescent efflorescences, and conspicuously coloured toxifications.


Watch the video: Phosphenes: What You See Behind Closed Eyes (August 2022).