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Color - Chapter 28

Red: Strength, pioneering spirit, alertness, sense of power, vitality, overcoming negative thoughts.

Orange: Social confidence, cheerfulness, resourcefulness, enjoyable relationships.

Yellow: Concentration, mental clarity, optimism.Green: Balance, peace, stress reduction,

calmness, self control, hope.Aqua: Openness, confidence, sensitivity.

Blue: Mental relaxation, peace, calmness, vitality, creativity, clear communication.

Indigo: Serenity, imagination, accurate perception, understanding, strong deep sleep.

Violet: Inspiration, calm nerves, creativity, beauty.Magenta: Relaxing, soothing, balance of emotions

Pink: Calming aggression, appetite suppressant.

Set of 10$106.95

Pink Floyd

The Color Spectrum –Newton’s Explanation

The Color Spectrum

• Newton—sunlight can be separated into a spectrum of colors when passed through a prism.

Red, orange, yellow, green, blue, violet

– White is a combination of all the colors.

– White objects reflect all visible frequencies.

– Black is the absence of light.

– Black objects absorb light of all visible frequencies.

• Visible black objects reflect some light—otherwise they would not be visible.

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How Humans See ColorDistribution of Cones – no blue at fovea

to avoid chromatic aberration.

Retina Map Secondary Colors

Blind Spot Test

http://en.wikipedia.org/wiki/Blind_spot_%28vision%29#Blind_spot_test

Color by Reflection• Different materials have different natural frequencies

for absorbing and emitting radiation.– Light is absorbed at the resonant frequencies where the amplitudes are

large.

– Frequencies above or below the resonant frequency are reemitted.

– Reemitted light passes through transparent materials.

– Reemitted light passes back into the medium from which it came if the material is opaque.

• The appearance of a colored object depends on the light source.– Things look yellowish in candlelight

– Incandescent lamps are rich in the low frequencies, enhancing reds

– Fluorescent lamps are rich in high frequencies, enhancing blues

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Color By Transmission

• The color of transparent materials depends on the color of the light they transmit.

– Pigments in the material selectively absorb certain frequencies of light.

– Red glass absorbs all the colors except for red.

– The energy of the absorbed light increases the kinetic energy of the atoms, warming the material.

Sunlight• White sunlight is a composite of all the

visible frequencies.

• The brightness of solar frequencies is

uneven

– Red and blue regions are not as bright as the yellow-green region.

– Humans are most sensitive to yellow-green light.

• This is why more and more fire engines are being painted yellow-green instead of red.

• This is also why yellow sodium-vapor lamps are often used for

street lights.

• Pay attention to the examples on the next

slides

• Understand what causes each color to

happen

– What is absorbed/reflected/transmitted, ect.

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Negative After Image

Adding Filters

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What Will You See?

What Will You See?

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Can you see color?

Color Blind Tests

Both the normal and those with all sorts of color vision deficiencies read it as 12.

The normal read this as 8.

Those with red-green deficiencies read this as 3.

Those with total color blindness cannot read any numeral.

The majority of those with red-green deficiencies read this as 5.

The majority of the normal and those with total color blindness cannot read any numeral.

Test Plate 3:

Normal will trace the orange line between the two X's.

The majority of those with color vision deficiencies will be unable to follow the line or will follow a line different to the normal one.

Test Plate 7:

The majority of those with red-green color

blindness can trace the winding line

between the two X's.

The majority of those with normal and total

color blindness are unable to follow the

line.

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Life's minor frustrations for the color blind:

• Weather forecasts - especially the Weather Channel - where certain colors just can not be distinguished on their weather maps.

• Maps in general because of the color coding on the legends. • Color observation by others: "Look at those lovely pink flowers on that

shrub". My reply, looking at a greenish shrub "What flowers?" • Test strips for hard water, pH, swimming pools, etc.: A color blind person is

generally unable to : – interpret some chemical reactions– see that litmus paper turns red by acid – identify a material by the color of its flame such as lead blue or potassium purple – interpret the chemical testing kits for swimming pool water, test strips for hard

water, soil or water pH tests - all of which rely on subtle color differences and a band of similar colors to compare against.

• Cooking and foods: – When cooking, red deficient individuals cannot tell whether their piece of meat is

raw or well done. Many can not tell the difference between green and ripe tomatoes or between ketchup and chocolate syrup.

– Some food can even look definitely disgusting to color deficient individuals. For example, people with a green deficiency cannot possibly eat spinach which to them just look like cow pat. They can however distinguish some citrus fruits. Oranges seem to be of a brighter yellow than that of lemons.

Pigments and Paints

Remember – Humans See Primarily Three Colors – Red,

Green, Blue

Each Paint Continues to Absorb Light – Even When Mixed with

Other Colors of Paint

• Cyan absorbs Red

• Yellow absorbs Blue

• Magenta absorbs Green

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Mixing Pigments

Mixing Colored Light

• White light is a mixture of all visible frequencies.

• White light can also be produced by overlapping red, green, and blue light.

– Red + green = yellow

– Red + blue = magenta (bluish red)

– Green + blue = cyan (greenish blue)

• Almost any color can be made by overlapping light of 3 colors and adjusting the brightness of each

color.

• Red, green, and blue are the additive primary colors.

– Color television uses only these three colors.

Complementary Colors• Colors produced by adding 2 of the 3 additive primary colors

together:Red + green = yellow

Red + blue = magenta

Blue + green = cyan

• Adding the 3rd additive primary color to the color produced by another two produces white:

Yellow + blue = white

Magenta + green = white

Cyan + red = white

• Complementary colors—two colors that produce white when they are mixed together.– White light from which a color is subtracted will produce the

complement of the subtracted color.

• Light that is absorbed by a material is subtracted from the incident light.– White light that strikes a pigment that absorbs red light will appear to be

cyan.

Mixing Colored Pigments

• Paints and dyes contain pigments that absorb light of certain frequencies and reflect light of other frequencies.– Blue paint reflects mostly blue, but also violet and

green.

– Yellow reflects mostly yellow light, but also red, orange, and green; it absorbs blue and violet.

– Blue and yellow together absorb all colors except for green.

• This is color mixing by subtraction.

• The subtractive primary colors are magenta, yellow, and cyan.

Cyan + Magenta

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Black CAN be created by mixing.

White CANNOT be created by

mixing.

Black is cheaper and better if it is just made from really black coal rather than

mixed from other pigments.

Why is the sky blue?

(28.8)

On the moon…Scattering

On Earth…

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Why is the Sunset Red?

28.9

Why are Clouds White?

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Why is Water Blue-Green?

28.10

Colors as they appear

underwaterOn some days, the water “looks” blue because blue light from the sky is reflected from the surface.

Red Sky reflected from water.

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Aurora Reflected

The Effect A Glacier Silt

Sometimes algae in the water make it “look” green.

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Thin Film Interference

Thin Film Interference

If the Thickness is Right – the Color Undergoes Constructive

Interference

Soap Bubbles Vary in

Thickness

Other Thin Film Colors – blue pigment is rare

Stop

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Kinds of Spectra Spectral Lines

Lines from excited sodium gas in the laboratory