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Color, Light, and Metamerism

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©2008 · Table of Contents Slide 2 of 69

Color, Light and Metamerism

Presented By: The Sherwin-Willliams Company2100 Lakeside Blvd. Suite 500Richardson, TX 75082

Description: Provides an overview of color, light, and metamerism and how they affect design choices.

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Learning Objectives

At the end of this program, participants will be able to:

• describe the nature of color and how it is perceived by the human eye

• explain metamerism and identify the different types

• illustrate how color temperature, color rendering index and spectral distribution curves aid in the selection of lighting fixtures and color, and

• predict how reflectance, texture and lamp choice will affect color and color choice.






Table of Contents

13

6

19

38

53

Click on title to view

Color and Vision

Light

Metamerism

Effects of Light on Color

Light Sources

66Summary






Color and Vision






What is Color?

Color is a sensation just like your sense of touch. It is caused by physical reality, but doesn’t have any physical reality of its own – an apple is not red and the sky is not blue. However, they have physical properties that make you perceive their color as red and blue. Color is not the property of the object which is causing the sensation.

Color and Vision






Color is Qualitative

Color is a property of visible light. It is one part of the electromagnetic spectrum that includes both radiation and infrared light. Each color is differentiated from one another by its wavelength. The eye and brain perceive variations in wavelengths to give the sensation of light.

Most data on color is qualitative, therefore it is a perceived quality.

“If one says red and there are 50 people listening, it can be expected

there will be 50 different reds in their minds.”

Joseph Albers

Interaction of Color

Color and Vision






Color and Vision

The eye is a complex receptor with rods and cones housed in the retina that respond to light by means of vibrations. Through an electrical-chemical process, these rods and cones send signals by way of the optic neurons to the visual center of the brain.

There are three types of cones within the eye: blue, green, and red, a tri-chromatic system. Through a complicated system of cell collaboration within the rods and cones, different colors are experienced. The three types of cones allow the human eye to see roughly seven million colors.

Not all signals are sent to the brain. Approximately 20% of the signals go to the pituitary gland, which is responsible for controlling growth hormones. When these signals get mixed up, an individual suffers from colorblindness.

Color and Vision






Color and Vision cont’d…

Most vision takes place in the brain, which reconstructs and interprets what it receives from the eye. What the eye really sees is very different from what we see. The picture below is a representation of an image as perceived by the left eye before processing by the brain.

Image as seen by the left eye

Color and Vision






Transforming Sight to an Image

There are several steps the brain has to do to transform the information the eye receives to an image we can “see”. Firstly, the brain has to merge the three colors perceived by the rods. This tri-chromatic system is similar to that of a TV, monitor or digital camera where three colors are the basis for all colors. The image at right is an enlargement of the previous image.

Enlarged portion of the previous image

The brain then performs color, light, and contrast enhancements to make the image appear real. It rotates what is seen by 180 degrees since what is projected on the retina is not in the proper orientation, but is upside down and mirrored. Next, the brain must take our binocular vision and merge the two images into a single image, different from the original two, but containing all of the two points of view of the two eyes. Finally, the brain must make corrections for errors, which can be myriad. If there is a problem with one eye, the brain will adapt and take some pieces of the image from both eyes. It is quite a complex series of functions.

Color and Vision






Color and Vision

As you can see, the image processed by the brain is much different from what is viewed from an individual eye. The brain transforms the view from our eyes in about 1/25 of a second so it is only reasonable that signals can get crossed and is remarkable that individuals can see colors and images with any degree of synchronicity.

Image after being processed by the brain

Color and Vision






Light






Light and the Visible Spectrum

Light is visual electromagnetic radiant energy with wavelengths ranging from 380nm to 780nm.

From left to right on top the scale, the range of waves present in the atmosphere ranging from cosmic rays to power and light rays are shown. Visible light is only a very small part of the waves in the universe. The colored chart below shows light waves including: ultra violet, visible, and infrared rays.

Light






Lighting Basics

Lighting can be described as:

• Art: Lighting designs have the potential to create drama and evoke a response. They can excite, motivate, and please.

• Science: There must be an understanding of science and the laws of physics for designers to comprehend how natural and artificial lighting works. To make a design work, an awareness of the technology of fixtures, lamps, and controls must be had so that they are combined in the correct way to meet the needs of the client.

• Theory: There are standard theories of application for all sources of types of fixtures. These theories are used because they have been proven over time with the use of science to create the art of an appropriately lit space.

Light






Lighting Basics cont’d…

Lighting is:

• a functional component of a space - we need it for vision and to see color

• a design element – it creates a sense of volume

• a complex subject dealing with the physics of electricity and light

• the creation and motivation for those in the space, and

• a creator of substantial energy demands, so it must be used wisely.

Light






Light

In 1666, Sir Isaac Newton was the first to realize that white light was a combination of all of the colors of the rainbow. Newton used the prisms to break sunlight up into its constituent colors. He discovered that if you take red, orange, yellow, and all the other colors of the rainbow in color pigments and mix them up, a murky brown-black is created, but if you do the same thing by mixing light from red, blue, and green filters, the result is white.

His experiments with prisms led the way for other scientists to probe the secrets of the spectrum.

Light






Light vs. Pigment

There is a basic difference between color in pigments, like paint, and color in light. That is, that the color in light is an additive system. All colors added together move toward white. With pigment, when you add all colors together you move towards black. It is a subtractive system.

Light

Source: www.wikipedia.org

http://www.wikipedia.org/






Metamerism






What is Metamerism?

Metamerism is the phenomenon that occurs when a pair of spectrally different specimens match under one illuminant and not another.

The fundamental reason for metamerism is that color is a sensation rather than a property of an object. As a result, the cones in the eyes can register the same sensation from an essentially infinite variety of combinations of different light frequencies.

Metamerism

Source: www.wisegeek.com

http://www.wisegeek.com/






Metameric Matches

Metameric matches occur when spectrally different colors appear identical under certain lighting conditions, but mismatched under others. Paints, finishes, textiles may look identical under incandescent lighting, but show a marked dissimilarity under fluorescent or other lighting sources.

Luminaires with different spectral compositions account for this mismatch as well as the use of different pigments and dyestuffs in the original materials. Since metamerismmakes it seemingly impossible to generate color matches under every light source, the color reproduction industry has grown immensely to take on the challenge.

The basis for nearly all commercially available color image reproduction processes such as photography, television, digital imaging are based on the ability to make metameric color matches.

Metamerism






Metameric Matches cont’d…

Metameric matches are quite common, especially in near neutral (grayed or whitish colors) or dark colors. As colors become lighter or more saturated, the range of possible metameric matches (different combinations of light wavelengths) becomes smaller, especially in surface colors. The appearance of surface colors is defined by the product of the spectral reflectance curve of the material and the spectral emittance curve of the light source shining on it. As a result, the color of surfaces depends on the light source used to illuminate them.

Making metameric matches using reflective materials is more complex. The appearance of surface colors is defined by the product of the spectral reflectance curve of the material and the spectral emittance curve of the light source shining on it. As a result, the color of surfaces depends on the light source used to illuminate them.

Metameric matches made between two light sources provide the tri-chromatic basis of colorimetry, the science of measuring color. Colorimetry is used in chemistry, in industries such as color printing, textile manufacturing, paint manufacturing, and in the food industry.

Metamerism






Types of Metamerism

There are four types of metamerism:• Sample• Illuminant• Observer• Geometric

Metamerism

Metamerism illustrated here by the graphic images at right. The original two dimensional triangle is filled with the RGB color r=255, g=0, and b=0. By changing the two-dimensional triangle to a three-dimensional image, adding a light source, and adjusting the viewing angle, this same color appears different even though the color resolution has not been changed. The images are all the same size and same color. There has also been no adjustment to the surface finish, which would add another element to the equation.






Sample Metamerism

Sample metamerism is defined as two color samples that appear to match under a particular light source, but do not match under a different light source.

The spectral reflectance distributions of the two samples differ slightly and their plotted reflectance curves cross in at least two regions. By illuminating them with light sources with considerably differing spectral power distributions, you can witness and even exaggerate the visual differences between the two samples.

Metamerism

Source: www.wisegeek.com and www.wikipedia.com

http://www.wikipedia.com/







Sample Metamerism cont’d…

For instance, when you put on two socks that appear to be black in a bedroom illuminated by incandescent lamps, then go into a kitchen that is illuminated by fluorescent lighting and discover that you have on a blue and a black sock. The differences in the wavelength distribution between the incandescent and fluorescent lights interact with the differences in the spectral reflectance curves of the socks to make them appear the same in one light source and different in another.

Incandescent light sources contain relatively little light in the shorter (blue) wavelengths, and therefore, it would be more difficult to distinguish blue colors under such lighting conditions. The fluorescent illumination in the kitchen emits more short-wavelength light, making the dark blue more easily distinguished from black. In incandescent light, the socks are a metameric match, but in fluorescent light they do not match.

Metamerism









Illuminant Metamerism

Illuminant metamerism occurs when you have a number of spectrally matched samples, but when each is independently, yet simultaneously illuminated and viewed under light sources whose spectral power distributions differ, significant variations in the color are observed. This phenomenon is rarely witnessed, unless you have a light box that allows you to view both light sources and samples separated by a divider.

Metamerism









Observer Metamerism

Since color is a perception, every individual perceives color in a different way, using a tri-chromatic system of red green and blue cones. This is assuming normal color signals traveling without incidence to the brain.

Observer metamerism occurs when two spectrally different objects viewed under an illuminant may appear to one observer to match and to another to not match. This is the reason there were 31 individuals tested to derive the 1931 International Commission on Illumination (CIE) “standard observer" values. These values are the chromatic response of the average human and have been adopted by the ISO (International Standards Organization) and are still used as the basis for the majority of color science study today.

Metamerism






Causes of Observer Metamerism

The common source of observer metameric failure is colorblindness, but it is also not uncommon among normal observers. In all cases, the proportion of long-wavelength-sensitive cones to medium-wavelength-sensitive cones in the retina, the profile of light sensitivity in each type of cone, and the amount of yellowing in the lens and macular pigment of the eye differs from one person to the next. This is particularly true of the aging eye and care should be taken to consider the yellowing of the lens as a perception difficulty.

This alters the relative importance of different wavelengths in a spectral power distribution to each observer's color perception. As a result, two spectrally dissimilar lights or surfaces may produce a color match for one observer, but fail to match when viewed by a second observer.

Metamerism






Geometric Metamerism

A geometric metamerism is defined as identical colors that appear different when viewed at different angles, distances, light positions, etc.

Metamerism

Note the squares labeled A and B in the image on the left. Are they the same or different colors? Now look at the image on the right and locate the same squares.

Source: www.wisegeek.com and www.wikipedia.org








Geometric Metamerism cont’d…

Normally, material attributes such as translucency, gloss, or surface texture are not considered in color matching. However, geometric metameric can occur when two samples match when viewed from one angle, but then fail to match when viewed from a different angle. A common example is the color variation that appears in pearlescent auto finishes.

It can be argued that one reason men and women often perceive color differently is that the distance between a woman's eyes is, on average, slightly less than a man's, and that slightly different angle of stereoscopic viewpoint also falls under the category of geometric metamerism.

Design professionals mitigate metameric failure by choosing the correct light source. Two crucial factors in choosing the right light source are:

1. Color temperature (chromaticity)2. Color rendering index (CRI)

Metamerism






Simultaneous Contrast/Bezold Effect

Take a moment and evaluate the images on this slide.

In the image on the left, the juxtaposition of the colors make it appear as if there are two different greens in the image, when in fact there is only one green in the image.

In the image on the right showing the brick wall, several things can be noted. The brick wall on the right appears to be a lighter shade of red than that on the left. Also, mortar joints in the right brick appear larger than the left wall.


Metamerism







Simultaneous Contrast/Bezold Effect cont’d…

Another bothersome complication for design professionals trying to match colors, is that colors actually change depending on the colors around them. The Bezold effect is an optical effect, named after a German professor of meteorology, Wilhelm von Bezold(1837-1907), who discovered that a color may appear different depending on its relation to adjacent colors.

The change in appearance of a central area in your field of vision because of a change in another area is called simultaneous contrast. It affects not only how much detail you can see, but shades and color as well.

Field-size metameric failure occurs because the relative proportions of the three cone types in the retina vary from the center of the visual field to the periphery, so that colors that match when viewed as very small, centrally fixated areas, may appear different when presented as large color areas. In many industrial applications, large field color matches are used to define color tolerances.


Metamerism







Metamerism and Industry

Using materials that are metameric color matches rather than spectral color matches is a significant problem in industries where color matching or color tolerances are important. A classic example is in automobiles: the interior fabrics, plastics and paints may be manufactured to provide a good color match under a standard light source (such as the sun), but the matches can disappear under different light sources (fluorescent or halide lamps). Similar problems can occur in apparel manufactured from different types of dye or using different types of fabric, or in quality color printing using different types of inks. Papers manufactured with brighteners are especially susceptible to color changes when lights differ in their short wavelength radiation, which can cause some papers to fluoresce.

Metamerism

Color matches in the paint industry are aimed at achieving a spectral and metameric color match. A spectral color match attempts to give two colors the same spectral reflectance characteristic, making them a good metameric match with a low degree of metamerism, and thereby reducing the resulting color matches sensitivity to changes in illuminant, or differences between observers.






Dealing with Color, Light, and Metamerism

The choice of lamp color and space color(s) is the prerogative of the lightingconsultant, the interior designer, and the owner. The decisions should be made jointlysince the interaction of the light and colored objects will affect the success of the installation.

There are a number of common sense rules of thumb that can help make color selection easier:• All space colors (wall and floor covering, furniture, drapes, accents, etc.) should be

chosen under the lamp color specified for the installation. Experience suggests that warm sources should be used at low lighting levels, cool sources at high levels. However, the choice may be influenced by space colors and by degree of luminaire brightness control.

• Warm color schemes may appear overpoweringly warm if lighted with a warm source to relatively high levels - use a cooler source.

• Cool color schemes may need warm sources, particularly at low lighting levels.• Where color rendition is critical, use high CRI continuous spectrum sources such as

fluorescent lamps with Chroma 50 (C50) or Chroma 75 (C75) phosphors.

Metamerism

Source: http://www.gelighting.com/na/business_lighting/education_resources/learn_about_light/color_matching.htm

http://www.gelighting.com/na/business_lighting/education_resources/learn_about_light/color_matching.htm






Dealing with Color, Light, and Metamerism cont’d…

• Where both color and lighting level are important, use the SP30, SP35, or SP41 tri-Phosphor fluorescent lamps for good color rendering and high efficiency. For even better color rendering and higher efficacy, consider GE's SPX30, SPX35 or SPX41 lamps.

• Tri-Phosphor lamps tend to make spaces look more colorful because the 3-peak phosphors compress all colors into the blue, green, and red-orange bands. This increases the contrast between colors. Three peak lamps do not, however, increase the contrast of black and white tasks. Claims that less light is needed for typical office and industrial tasks when they are used are scientifically unfounded.

• The color of a light source does not affect the visual performance of people doing black-on-white visual tasks. Vision and productivity studies, however, indicate that productivity may be affected by the color contrast and appearance of the visual environment and that color can contribute strongly to appearance.

Metamerism






Overcoming Metameric Failure

There are two crucial factors when choosing lighting in order to overcome metameric failure, Kathy Presciano, ASID says:

1. The light source’s color temperature, or chromaticity, which refers to the perceived warmth or coolness. This is a scientific measurement of the wavelengths making up the light, called the degrees Kelvin. The higher the degrees Kelvin, the cooler the light.

2. The color rendering index, or CRI, is a number between 1 and 100. The higher the CRI, the better the lamp will make colors appear.

Metamerisim






Considerations to Counter Metamerism

Other lighting factors to consider to control how color is rendered:• color temperature of lamps• light intensity of lamps• position from which the color is viewed• condition and age of any filters applied to light sources• cleanliness of light sources• age and condition of lamps• voltage of input power• age and condition of electronics• ambient viewing condition, presence of smoke, dust, bright fabrics or colors, and

ambient light entering the area

Metamerism







The type of light under which color is viewed makes a tremendous difference in how we perceive a particular hue. In addition, the chosen color may look different at various times of the day or night. Color shifts are usually the result of the attributes of the light source; i.e., the color rendering index and the color temperature.







Color Temperature

Color temperature is a way to characterize the color quality of white light. It is used in a variety of applications including photography (determining the correct film depending on the lighting) and lighting design (specifying the right light source types).

Color temperature is measured, in degrees Kelvin, by comparing it to the light radiated by a theoretical black body when heated. When heat is applied to the black body, the first color emitted is deep red. With increasing amounts of heat and increasing temperatures, the colors move from red to orange, through the visible spectrum to white, blue and violet.

When the black body reaches 2,800 degrees K, it looks like a normal incandescent lamp. At 5,000 degrees, the quality of its light is akin to daylight.







Color Temperature cont’d...

The temperatures at which specific colors are emitted from the black body are used to describe the color quality of light. For instance, the general color temperature emitted by an incandescent lamp is 2600-3100 °K.

Color temperature is associated with the apparent color of the light emitted by the black body and not the intensity of the light being emitted.

1800°K (sunlight at sunrise or a candle flame)

Cool Black Body

25,000°K (northwest sky)

2600-3100°K (incandescent lamp)

4870°K (sunlight at noon)







Color Temperature cont’d..

Color temperature runs opposite to how designers most often describe colors. For designers, a red or yellowy light such as incandescent, would be referred to as “warm” and a white or blue light would be referred to as “cool”. The warm colored light from a setting sun has a lower color temperature than the cool color of daylight during a cloudy day. Remember, color temperature and light intensity are two independent quantities.

CoolWarm

Increasing Color Temperature

1800°K 4,870°K 25,000°K







Color Temperature cont’d..

Most lighting manufacturers use the baseline of the incandescent lamp at 2600-3100°K.

The standard “cold, blue/green fluorescent lighting” is a thing of the past. Warm, white fluorescents are available with a color temperature of 3000°K and cool whites at 4200°K.

Thus, it is critically important to the designer to understand the color temperature of lamps as well as the Color Rendering Index (explanation to follow) to avoid costly mistakes in color matching.







Color Rendering - Chromaticity

The chromaticity of a light source defines its whiteness, yellowness, or blueness as well as its warmth or coolness. However, it does not define how natural or unnatural colors of objects will look when lighted by the source. Two colors of lamps can have the same chromaticity, but render colors very differently.

Whiteness/CoolnessBlueness Yellowness/Warmth

Metal Halide Low Pressure Sodium







Color Rendering Index (CRI)

The Color Rendering Index (CRI) is a quantitative measure of the ability of a light source to reproduce the colors of various objects faithfully in comparison with an ideal or natural light source at the same color temperature. Light sources with a high CRI are desirable in color-critical applications such as photography and cinematography.

The CRI ranges from 0 to 100 with 100 being the best possible reproduction of color. In theory, the CRI is supposed to compare the color rendering ability of a light source operating at a given color temperature to that of a black body at the same color temperature.

For a source like a low-pressure sodium vapor lamp which is monochromatic, the CRI is nearly zero, but for an incandescent lamp, which emits essentially black body radiation, it is nearly 100. CRI is a general indicator of how natural colors appear when illuminated by a particular light source. Generally, a CRI of 80 and above will be required for most lighting applications.







Color Rendering Index cont’d…

The color rendering index is only one measure used to help identify how accurately a color will appear. However, the lighting source must have the same color temperature for this to be completely accurate that is why CRI is not the only measure that should be used and why many people do not rely solely on the CRI.

The CRI is most frequently used by daylight fluorescent manufacturers in proving that the light provided by their lamps has good color rendering abilities. However, in practice, the CRI has its limitations which will be explained on the next slide.







Color Rendering Index Limitations

CRI is useful in specifying color only if its limitations are understood. It was designed to compare continuous spectrum sources whose CRI’s were above 90. With CRI’s below 90, it is possible to have two sources with the same CRI, but which render color very differently. At the same time, the colors lighted by sources whose CRI’s differ by 5 points or more may look the same. Colors viewed under sources with line spectra such as mercury, metal halide, or high pressure sodium lamps may actually look better than their CRI would indicate. However, some exotic fluorescent lamp colors may have very high CRI’s while distorting some object colors substantially.

CRI’s can only be compared with sources of the same chromaticity. This is dramatically noticed when one considers that white fluorescents at 3000K and daylight fluorescents at 6250K have CRI’s of 77 and 75. Colors under white fluorescents look significantly better than under daylight, yet the CRI’s are essentially the same.







CRI Comparison – Artificial Light

The table on this slide illustrates the differing color rendering indices of artificial light sources. Note that incandescentand halogen sources have equal CRI numbers, while the degrees of Kelvin are a bit more disparate. Also, while the color temperature of warm white fluorescent is in the incandescent and halogen range, the CRI is very low, meaning the color rendering under this light source would be poor.







Spectral Power Distribution (SPD)

Spectral Power Distribution curves provide the user with a visual profile of the color characteristics of a light source. They show the radiant power per unit area per unit wavelength emitted by the source at each wavelength or band of wavelengths over the visible region (400 to 700nm). Lamp manufactures publish SPD curves of specific light sources. The spectral make-up of a light source affects its ability to render colors “naturally”.







Spectral Power Distribution (SPD) Curves – Sun/Sky and Incandescent

An incandescent lamp has a CRI close to 100. This does not mean that an incandescent lamp is a perfect color rendering light source. It is very weak in blue and black under low levels of incandescent lighting. On the other hand, outdoor north sky daylight is weak in red, so it is not a perfect color rendering source either, but it also has a CRI of 100 by definition.

Note that incandescent lamps and natural daylight produce smooth, continuous spectra.







Spectral Power Distribution (SPD) Curves – Fluorescent

This slide illustrates the Spectral Power Distribution (SPD) curves of two types of fluorescent lamps. In both the warm white and cool white lamps the area of blue and green light, including spikes in these areas, outweighs the warm colors.

Warm White Cool White







Spectral Power Distribution (SPD) Curves – Fluorescent cont’d…

In the deluxe lamp examples shown below, power is lower overall, allowing the warm color representation to be more prominent, however they still show marked spikes in the blue and green ranges.

These SPD curves are in direct contrast to the smooth, continuous spectra of the incandescent spectral power distribution curve.

Cool White DeluxeWarm White Deluxe







Light Sources






Light Sources

There is no "best" color lamp nor is there any formal definition of "true" color. Each spectral distribution distorts object colors compared to another, whether the light comes from a natural source such as sunshine, north skylight, sunset, or electric sources such as incandescent, fluorescent, and HID. The right color source for a given application depends on personal preferences, custom, and, to a very large extent, an evaluation of the tradeoffs in efficiency, cost, and color rendition.

Light Sources






Light Source Contributions to Color

The type and amount of artificial lighting in a room will affect the perception of color and should be considered when making selections. A quick guide to the effects of the most popular lighting sources follows:

• incandescent lights cast warm yellow or amber tones that can intensify wall colors • standard fluorescent fixtures bring out cool tones and green casts • warm fluorescents, while not as rich as incandescent sources, add warm casts • halogen lighting is bright and white and distorts color less than any other artificial light

source - however, it does tend to cool colors

Light Sources






Light Reflectance and Color

Reflectance is the proportion of light that a surface reflects compared to the amount of light that falls on that surface. Light reflective values (LRV), as noted on paint chips, measure the reflection from painted surfaces that cause them to act as a secondary light source. In environments with low amounts of natural light, a color with high LRV may be most suitable.

Light Sources






Light Reflectance and Color cont’d…

The reflectance value of an individual color indicates the amount of light and heat thatcolor will reflect. Black has a reflectance value of zero and absorbs all light and heat.Surfaces low in reflectance value are generally very dark and can get very hot (such asthe black leather seats in a car). On the other hand, white has a reflectance value of nearly 100 and keeps a building light and cool. All colors fit between these two extremes. A color with a reflectance value of 60 (which means it reflects 60% of thelight that falls on it) will reflect more light than a color with a reflectance value of 30(which means it reflects only 30% of the light that falls on it).

Typical reflectance values for room surfaces:• white acoustical ceiling tile - 70-80%• light–colored walls - 40-60%• carpet - 15-30%

Light Sources

Please remember the exam password REFLECT. You will be required to enter it in order to proceed with the online examination.






Light Reflectance and Finishes

The amount of light reflected off a color is the degree of gloss or sheen.

There are four types of sheen:• flat• satin• semi-gloss• gloss

Light Sources






Light Reflectance and Finishes cont’d…

Flat finishes:• offer matte appearance• absorb more light• reflect less light, but hide surface blemishes

Satin Finishes: • absorb less light than flat finishes• work best in high traffic areas• are easier to clean• are useful in environments with elder

residence as there is no undue glare

Semi-gloss:• more highly reflective• very durable

Gloss Finishes:• most light reflective• provide a lustrous, hard wearing finish• produces quite a bit of glare (dependent

on light source)

There are no industry standards regarding these finishes. Due to advances in paint technology, higher sheen does not always mean more washable.

Light Sources






Light, Color, and Texture

Light, color, and texture are inherently linked. If a room’s color is changed from bright lemon yellow to British racing green, the light reflectance of the room will decrease, making the room appear darker.

In the adjacent image all exterior surfaces were painted the same color – due to the various textures of the materials, the color appears to be different.

Remember that matte surfaces will absorb the light and will always appear darker and deeper than glossy reflective surfaces. This can make colors that were custom colored appear to be mismatched when applied to surfaces that are of differing textures. For instance, the same color can have a different appearance on carpet or fabric than it does on paint.

Light Sources






Light, Color, and Texture cont’d…

On the interior view, shown at right, the same paint was selected for all surfaces: walls, trim, and ceiling. Since these surfaces have somewhat different textures, they appear to be a different color.

However, the primary reason for the appearance of differing colors is the juxtaposition of intersecting planes and the natural light on some surfaces.

Light Sources






Layers of Color and LRV

What happens when color is layered upon color? When dealing with paint color matching, a gray-tinted basecoat can help you avoid metameric problems.

Gray-tinted basecoats allow designers to achieve the ideal balance of light absorption and reflection by working within the color space of the topcoat color. For certain deep, bright or transparent colors, a gray basecoat:

Sherwin-Williams.comSherwin-Williams.com

• allows an accurate color match in fewer coats • allows better touch-up and superior coverage

of surface imperfections, and• provides uniform colors with less streaking.

Light Sources






Light, Color and Texture Merged

This image of the Craft Restaurant in New York City, illustrates the symbiotic merging of color, texture and light and is a treat to our senses.

Light Sources






Adaptation

First impressions of the color of an environment will not last and will change with time, just as a hand adapts to the temperature of hot water in which it is placed, so the eye will adapt to color.

Sources used for general lighting will gradually appear to become white to the viewer, whether they are yellow/white like incandescent, or blue/white like daylight.

Within reason, the human color vision process tends to compensate or fill in for those colors lacking in the spectrum; red in the case of daylight, blue for incandescent, etc.

Light Sources






Adaptation cont’d…

The eye's previous state of adaptation is also a factor. A warm environment will look even warmer to an occupant if he or she enters it from a cold, bluish space. It will look cooler if he or she has been in a yellowish or pinkish one. The eye then slowly adapts until the space appears to be lighted with white light, no matter what the eye was adapted to previously.

This suggests that, while side-by-side color comparisons are an excellent way to show the differences between light sources, they are not practical since the eye never becomes adapted to either source, but to a combination of both. A final color evaluation would be better made using a relatively large space, with only one color lamp lighted at a time.

In the final analysis, the ultimate test is to live with the color or colors for an extended period of time. This way color can be viewed under a variety of light sources and situations, mitigating first impressions and adaptation effects.

Light Sources






Summary






Summary

Color is a property of visible light. It is one part of the electromagnetic spectrum that includes both radiation and infrared light. Each color is differentiated from one another by its wavelength. There are myriad of methods to quantify and calibrate color to aid in color use and choice and an equal number of effects like reflectance, adaptation and quality of light that can make these choices difficult.

In the end….

“Artists and designers have been studying the effects of colors for centuries and have developed a multitude of theories on the uses of color. The number and variety of these theories demonstrates that no universally accepted rules apply; the perception of color depends on individual experience."

Encyclopedia Britannica

Summary






Course Evaluations

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©2008 The Sherwin-Williams Company. The material contained in this course was researched, assembled, and produced by The Sherwin-Williams Company and remains their property. Questions or concerns about this course should be directed to the instructor.

Conclusion of This Program

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