What is the Visible Spectrum

The range of light from red to violet in a rainbow that is visible to the human eye is called the visible spectrum. Please take note of the emphasis on human! The visible spectrum is a tiny portion of something much larger the electromagnetic spectrum.

The only reason we have a special name for the visible part is because our particular anatomy is responsive to these particular wavelengths of light. At one end of the electromagnetic spectrum, beyond red light with its longer wavelengths and lower frequencies, are even longer wavelengths and even lower frequencies of light that include infrared, microwaves, and radio waves.

At the other end, beyond violet light with its shorter wavelengths of light and higher frequencies, there are even shorter wavelengths of light with even higher frequencies that include ultraviolet (UV) rays, X-rays, and gamma rays. Just as the borders between colors are fuzzy and arbitrary. so are the borders between these other parts of the electromagnetic spectrum. X-ray is just another color," like orange, in that it encompasses a range of wavelengths of light. It's just that we humans can't see this color.

It's important to note that the visible spectrum as it is typically illustrated does not contain all the variations of colors that humans can see; rather, the spectrum is used to represent only the pure spectral colors made up of individual wavelengths of light. The bulk of the colors we see every day are actually made up of a mixture of wavelengths of light

The Most Important Factor that Impacts Color Perception

Lighting is easily the most important factor when it comes to color perception. First, let’s dive into the science. Some of it may sound familiar if you’ve taken an art class before:

We can only see objects that reflect light into our eyes, and the color we see depends on the wavelengths of light that are reflected. When the visible spectrum is reflected equally, we perceive an object as white. When it absorbs most light, we see it as black. Color in light, unlike pigment, depends on the spectral energies contained in the light. Objects that appear red reflect the red energy while absorbing all others. Without the red energy, a normally “red” object will appear black. Light we perceive as “cool” includes more blue, whereas “warm” light is more yellowish light. The color of a light source can be described by measuring the relative powers of various wavelengths. As this spectral power distribution (SPD) changes, so does the way light is reflected to our eyes, which affects the colors we perceive.

Cones Influence Color Perception

Your retina has two different types of cells that detect and respond to light—rods and cones. These cells that are sensitive to light are called photoreceptors. Rods are activated when you’re in low or dim light. Cones are stimulated in brighter environments. Most of us have about 6 million cones, and 110 million rods. Cones contain photo pigments, or color-detecting molecules. Humans typically have three types of photo pigments—red, green and blue. Each type of cone is sensitive to different wavelengths of visible light. In the daytime, a lemon’s reflected light activates both red and green cones. The cones then send a signal along the optic nerve to the visual cortex of the brain. The brain processes the number of cones that were activated and the strength of their signal. After the nerve impulses are processed, you see a color— in this case, yellow.

In a darker environment, the light reflected by the lemon would stimulate only the eyes’ rods. If only the rods are activated, you don’t see color, just shades of gray. Your past visual experiences with objects also influence your perception of color. This phenomenon is known as color constancy. Color constancy ensures that the perceived color of an object stays about the same when seen in different conditions. For example, if you looked at a lemon under a red light, you likely would still perceive the lemon to be yellow.

Moureaux chose paper; layering over 100,000 number cutouts into a 3D grid. From sunrise at 6:30 to 19:49, the numbers turn over 100 shades of color, ending in black. A color changing experience totaling 799 minutes.

“When I make works from light boxes (such as Brick Lane Remix, 2003), or old plastic bottles with lights inside, I hope the illumination suspends their objecthood to some degree and makes the viewer see them a little differently – see them as colours before seeing them as objects.”

While Yellow can be an energetic color, this intensity can also have a downside. Sometimes yellow can come off as very aggressive and even confrontational.

In great quantities, people may be left feeling irritated or even angry when surrounded by yellow.

Does color really affect our mind and body?

Like the ear, which also provides us with our sense of balance, we now know that the eye performs two functions. Light sensitive cells known as cones in the retina at the back of the eye send electrochemical signals primarily to an area of the brain known as the visual cortex, where the visual images we see are formed. However, we now know that some retinal ganglion cells respond to light by sending signals mainly to a central brain region called the hypothalamus which plays no part in forming visual images. The retinal cells that form the non-image-forming visual pathway between eye and hypothalamus are selectively sensitive to the short wavelengths (blue and green) of the visible spectrum. What this means is that there is clearly an established physiological mechanism through which colour and light can affect mood, heart rate, alertness, and impulsivity, to name but a few. For example, this non-image-forming visual pathway to the hypothalmus is believed to be involved in seasonal affective disorder, a mood disorder that affects some people during the darker winter months that can be successfully treated by exposure to light in the morning.

Color and Psychological functioning

In the past decade there has been increased interest in research on color and psychological functioning. Important advances have been made in theoretical work and empirical work, but there are also important weaknesses in both areas that must be addressed for the literature to continue to develop apace. I conclude by reiterating that the literature on color and psychological functioning is at a nascent stage of development, and by recommending patience and prudence regarding conclusions about theory, findings, and real-world application. In the following, I review the diverse areas in which color work has been conducted in the past decade, and the findings that have emerged.

In research on color and selective attention, red stimuli have been shown to receive an attentional advantage (see Folk, in press, for a review). Research on color and alertness has shown that blue light increases subjective alertness and performance on attention-based tasks (see Chellappa et al., 2011, for a review). Studies on color and athletic performance have linked wearing red to better performance and perceived performance in sport competitions and tasks (see Maier et al., in press, for a review). In research on color and intellectual performance, viewing red prior to a challenging cognitive task has been shown to undermine performance (see Shi et al., 2015, for a review). Research focused on color and aggressiveness/dominance evaluation has shown that viewing red on self or other increases appraisals of aggressiveness and dominance (see Krenn, 2014, for a review). Empirical work on color and avoidance motivation has linked viewing red in achievement contexts to increased caution and avoidance (see Elliot and Maier, 2014, for a review). In research on color and attraction, viewing red on or near a female has been shown to enhance attraction in heterosexual males (see Pazda and Greitemeyer, in press, for a review). Research on color and store/company evaluation has shown that blue on stores/logos increases quality and trustworthiness appraisals (see Labrecque and Milne, 2012, for a review). Finally, empirical work on color and eating/drinking has shown that red influences food and beverage perception and consumption (see Spence, in press, for a review).

Why is color such a powerful force in our lives? What effects can it have on our bodies and minds? While perceptions of color are somewhat subjective, there are some color effects that have universal meaning.

While the west took centuries to develop an art that looked beyond sacred borders, the Chinese were embedded in an acute perception of the world around them.

"Growing up with a Chinese background gave me insight into a completely different culture, with different customs, relationships and emotions; a lifestyle very different to that found here in Canada."

"I am inspired by the beauty in the ordinary . . . to transform the spirit of the living into art"

This was reflected in much of his work which deals with a variety of subjects from the village scenes (which glow with the innate energy of humans in their day to day lives) to masks (for him a reminder of what once lived) and abstract renditions of the complexities of love.

How language shapes the way we think

I'll start with an example from an aboriginal community in Australia that I had a chance to work with. These are the Kuuk Thaayorre people. They live in Pormpuraaw at the very west edge of Cape York. And what’s cool about Kuuk Thaayorre is, in Kuuk Thaayorre they don't use words like left and right. And instead everything is in cardinal directions, north, south, east and west. And when I say everything, I really mean everything. You would say something like "Oh, there's an ant on your Southwest leg." Or "move your cup to the north north east a little bit." In fact the way that you are saying „hello“ in Kuuk Thaayorre is you say, „Which way are you going?“.

[…]

In fact people who speak languages like this stay oriented really well. They stay oriented better then we used to think humans could. We used to think that humans are worse than other creatures because of some biological excuse. „Oh, we don’t have magnets in our beaks or in our scales.“ No, if your language and your culture trains you to do it, actually, you can do it. There are humans around the world who stay oriented really well. And just to get us in agreement about how different this is from the way we do it, I want you all to close your eyes for a second and point southeast. […] I see you guys pointing there, there, there, there, there… I don’t know which way it is myself. You have not been a lot of help. So let’s just say the accuracy in this room was not very high. This is a big difference in cognitive ability across languages, right? Where one group, very distinguished group like you guys, doesn’t know which way is which but another group, I could ask a five-year-old and they would know.

The way you see color depends on what language you speak

Since the day we were born we have learnt to categorise objects, colours, emotions, and pretty much everything meaningful using language. And although our eyes can perceive thousands of colours, the way we communicate about colour – and the way we use colour in our everyday lives – means we have to carve this huge variety up into identifiable, meaningful categories. Painters and fashion experts, for example, use colour terminology to refer to and discriminate hues and shades that to all intents and purposes may all be described with one term by a non expert.

Different languages and cultural groups also carve up the colour spectrum differently. Some languages like Dani, spoken in Papua New Guinea, and Bassa, spoken in Liberia and Sierra Leone, only have two terms, dark and light. Dark roughly translates as cool in those languages, and light as warm. So colours like black, blue, and green are glossed as cool colours, while lighter colours like white, red, orange and yellow are glossed as warm colours. The Warlpiri people living in Australia’s Northern Territory don’t even have a term for the word “colour”. For these and other such cultural groups, what we would call “colour” is described by a rich vocabulary referring to texture, physical sensation and functional purpose.

Remarkably, most of the world’s languages have five basic colour terms. Cultures as diverse as the Himba in the Namibian plains and the Berinmo in the lush rainforests of Papua New Guinea employ such five term systems. As well as dark, light, and red, these languages typically have a term for yellow, and a term that denotes both blue and green. That is, these languages do not have separate terms for “green” and “blue” but use one term to describe both colours, a sort of “grue”.

People see colours differently according to the way their language categorises them. Historically, Welsh had a “grue” term, namely glas, as did Japanese and Chinese. Nowadays, in all these languages, the original grue term has been restricted to blue, and a separate green term is used. This is either developed from within the language – as is the case for Japanese – or through lexical borrowing, as is the case for Welsh. Russian, Greek, Turkish and many other languages also have two separate terms for blue – one referring exclusively to darker shades, and one referring to lighter shades.

Cross-Cultural Emotion and Symbolic Meanings of Color

The colour is an inseparable part of our everyday lives and its presence is evident in everything that we perceive. It is widely recognized that colours have also a strong impact on our emotions and feelings. The colours are found to trigger certain psychological, physical, biological and metabolic reactions within humans. The colour is the fundamental building block of visual symbols and serves as a communication method for humans. However, colour may generate another level of meaning in the mind. The colour symbolism arises from cultural, mythical, historical, religious, political, and linguistic associations. The symbolic meanings of colour words reveal wide-ranging connotations in cultures including positive and negative meanings. While particular colours have been found to be highly preferred regardless of age, racial group, or culture. On the other hand, Colours affect our functioning before we are conscious of it and deliver important messages.

Colours are used in flags and national colours to identify groups and countries. Colours are used in different signs to warn us of danger and make us alert. In ancient civilizations, colour was an integral part of the substance and being of everything in life. It is also closely associated with mental and emotional states and can affect them profoundly. Most fundamental colour symbolism was drawn from nature. Thus, green symbolized potency in arid regions but a sacred colour in Islam. Blue stood for the sky, and also for the spirit and truth. Interpretations of colour may differ and the symbolism varies with the cultural environment. The colour black and the colour white clearly stand for duality and antithesis. Red, the colour of blood, is usually linked with living, but it represents death in the Celtic world.

The socio-cultural, religious context within which a person was brought up also may mould the above association. Culture could be defined as an amalgamation of the attitudes, values, ethics, norms, customs, beliefs, rituals, mythology, scriptures, doctrines, and all the art forms accepted and practised through generations by a certain group of people.

“If I had a choice, I might not use color,” she admits, acknowledging that black-and-white jobs are rare. Therefore, when it comes to her personal work, both color and computer are absent in what she describes as a very organic process.

The two other groups of works refer to the present of Afghanistan(2009) and the past of the ‘Wall’ that fell in Berlin 20 years ago. In the former, a Taliban activist is shown in ‘Angel of Death Metal’, clutching a bright red Fender Jaguar, a lone figure surrounded by dark clad special forces, brothers of the riot police from ‘Dog Planet’.

"The illu that refers to Matisse was originally a sketch for a client that didn’t get through. But I liked the idea and finished it on my own. Playing with famous scenes can be very entertaining as the observer immediately recognized the image but experiences something else in it, too. I deeply admire artists who use humour and metaphors clever and aim on that often myself in my illustrations."

Color The Temple: Using Projected Light to Restore Color

One of the goals of the MediaLab is to explore the use of design and emerging technologies to improve the museum experience. Projection mapping, also known as spatial augmented reality, is a technology that can turn physical objects and buildings into a surface for projected light. This technique creates an enhanced experience for the audience by combining digital information with real objects. While the MediaLab was exploring how projection mapping could be used in the Museum, an opportunity arose to collaborate with the Department of Egyptian Art.

Did You Know The Temple Wasn't Always Beige?

Temples in Egypt, and in much of the ancient world, were not only carved with detailed reliefs, but also painted with vivid colors, like the example from the Karnak Temple Complex shown above. The small square shows a cleaned surface in an otherwise soot- and grime-covered relief scene. This small section at Karnak allows visitors to see the temple in new ways, and we set out to do this digitally with The Temple of Dendur.

Research on Colors and Patterns

To start the process of our digital recreation of the colors on The Temple of Dendur, we began by using a variety of sources—including the Temple itself, surveys of both Dendur and other temples, and objects from the Met's collection—to research the original colors of the Temple. Looking first to the Temple, we considered exploring several of the scenes. Ultimately, we focused on one scene in which the figures and glyphs were well preserved in the stone, because it would allow us to isolate various elements to tell the story of the scene. Logistically, we needed to be on the south wall, away from the direct sunlight coming through the windows, so that the natural light wouldn't wash out the projected light.

We looked for remnants of color on this scene, both with the naked eye and a technique known as visible-induced luminescence (VIL) imaging, but, unfortunately and unsurprisingly, we found none. Although the arid desert is a good environment for preserving antiquities, sand and wind erosion over two thousand years, as well as flooding, deteriorated the surface. However, early reports regarding the Temple before it was flooded provided some key insights.

Making It Digital

The first step in the process of projecting colors onto the Temple was to create a digital version of the scene we chose. We used high-resolution photographs of the south wall, where our chosen scene was located, as a reference for our recreation. Our goal was to create a type of image that we could use to easily switch the colors of different parts of the scene, so we decided to make a vector-based image instead of a raster, pixel-based image because this type of image would allow us to easily change the style of each shape independently. We imported the photographs in Adobe Illustrator and added a layer to the image so that we could trace the original lines of the scene.

One of the benefits of our project was having access to the Temple as the primary resource for research. Once we started creating vector images and line drawings, it became apparent that the original carved lines of some of the hieroglyphs and figures were subject to erosion and therefore not very visible. We didn't want to simply copy and paste from what past scholars thought the Temple's carving should look like. Instead, we compared our line drawings and previously published versions of the hieroglyphs and figures with the stone itself, and came up with a version that combined that information.

We used MadMapper to align our drawing with the Temple because it allowed us to modify the graphics on screen such that they would appear correct if the projector was not facing the Temple straight on, or if we needed to make small adjustments to align with the carvings on the irregular surface of the stone. We bridged openFrameworks and MadMapper with Syphon, a plug-in that enables image sharing across applications in real time.

What's Next

Through rigorous research, prototyping, discussion, and iteration, we have managed to cast new light on the Temple by presenting it in a fashion much closer to its original form for the first time in many millennia. Using relatively recent advances in software, we were able to experiment with restoration using nondestructive means (projected light rather than a material like paint) to temporarily display content without presenting any challenges for conservation.

"Ever since I was a child, I have been fascinated by history and archaeology. I think humans perceive the past as a series of events; something like a movie that we can’t really feel or touch. I believe the things that bring us closer to the past are those that truly humanize us – the bodies from Pompeii, the perfectly preserved Inca mummies, the personal objects of those long gone, and more."

What we got back demonstrates just how differently we all see the world — with each artist putting their own unique flavor on the original image.

What is Color?

On a simple level, color is first and foremost a personal experience. It is an important part of the total visual and emotional experience we have, for example, when standing at the edge of the Grand Canyon at sunset, or when walking through the galleries of the Uffizi Museum in Florence. We can identify without difficulty with the statement of the philosopher Bertrand Russell: “I know [a] color perfectly and completely when I see it” (Russell 1912). But communication about color is problematic. There is little if anything objective about color experiences, only each individual knows what she or he experiences. Any objective part of color deals entirely with the definition of color stimuli, but, as discussed in more detail in Chapter 4, there is considerable variation in color stimuli perceived as having unique hues, particularly for green and red. There is as yet no indication that selection of such stimuli is tied to variation in specific cone sensitivity of the observers and the presumed resulting subtractive opponent color functions. Color perceptions seem to be generated in detail at a level of brain activity beyond that of the first generation of cone opponent signals.