Lesson 7: Color Perception
Perception of Color
As you just learned our eyes are lined with receptor cells that detect light, but what exactly are we detecting? Visible light is a form of electromagnetic energy described in wavelengths. Here are 2 key terms for understanding light:
Wavelength: Distance from 1 peak to another
Nanometer: 1 billionth of a meter
The range of visible light is about 380 - 760 nanometers and is a tiny fraction of the electromagnetic spectrum. Look at the image below. Of all the EM (electromagnetic) energy bouncing around us, we can only see that tiny sliver. Yet, that sliver is enough for use to distinguish millions of colors!
Source:http://www.werkstattworkshop.com/?q=education/lessons/vcosci5 Links to an external site.
What is Color?
So, we are able to detect a specific range of EM energy, but what is color?
Importantly, colors are a perception - colors do not exist until we see them! Without the specific mechanics of our eyes there is no such thing as color; in other words the colors are not "in" the objects. Color, then, is an interaction between the physical energy bouncing off objects and our receptor cells (specifically our cones).
Color is truly a psychological experience. Light, however is measurable. Therefore, scientists try to quantify color in terms of physical properties. It is important to remember that the two are distinguishable. A quantification of light is not a quantification of the psychological experience of it.
Objects absorb some wavelengths are reflect others. White reflects all visible wavelengths whereas black absorbs all wavelengths. Our cones are able to detect the energy reflected by an object within the visible spectrum. Certain wavelengths are longer and interpreted as red; medium lengths may appear yellow whereas short wavelengths may look blue. Here are a few diagrams that may help you understand:
Qualities of Color
Hue, brightness and saturation are qualities of color.
Hue is defined as the quality of a color as determined by its dominant wavelength, i.e. a hue is a unique wavelength on the color spectrum. Hue is independent of saturation or brightness (definitions to follow). It is measure of color - hue is basically what we think of when we think of a color, for example: red maroon, blue, and aquamarine. Have fun playing with this example Links to an external site..
Brightness: A measure of the overall intensity of the image. The lower the brightness value, the darker the image; the higher the value, the lighter the image will be. Brightness measure of luminosity.
Saturation: The purity of a color's hue, moving from gray to the pure color. A high saturation corresponds to a strong color.
To investigate this yourself, you can use this interactive web-site Links to an external site. that lets you change the 3 properties.
Alternatively, you can open Microsoft Word, Highlight some words and then go where you are able to change the font color. Select HSL (for hue/saturation/luminance - another word for brightness). You should see a box with all the colors. Note that at the bottom, the colors fade to gray and toward the top, they are more clear. This is the saturation quality. Notice on the side that you can go from white to black and all shades of your color in between. This is brightness. Also, note the hue can be changes from left to right.
Take a minute to take some notes: Recreate Magritte's color palette using the tools from Word or using this link
Links to an external site. What did you learn from this experience?
TEST YOUR KNOWLEDGE: Hue, Brightness, or Saturation?
Theories of Color
General Color Theory:
Based on Newton's discovery of Prismatic Colors
Links to an external site., fundamental colors that can't be broken down or changed and Chevreul's 1839 Color Wheel
Links to an external site., Color theory presents a systematic way to mix colors harmoniously (or not).
When you want something to stand out, use complementary colors - or the opposite color on the wheel. For example, red-green and purple-yellow combinations tend to "pop." If you want something with a little less "pop" you could choose a split-complementary scheme - that is choose a color, find it's opposite and choose the two colors next to that opposite color. So, you might have a palette of blue-yellow-orange. If you want a more harmonious, tranquil look choose analogous colors, that is colors right next to each other on the wheel. So, you may choose a range of blues and greens for a cozy feel to a composition. A triadic color scheme includes 3 colors equally spaced apart on the color wheel, like purple-orange-green. This creates a more vibrant look.
TEST YOUR KNOWLEDGE: Complementary, analogous, triadic or split
All of this is based on the idea of simultaneous contrast, or that a hue appears different when the surrounding hues change. Josef Albers is the king of simultaneous contrast experiments and is famous for his color experiments Links to an external site.. The two squares below are exactly the same color.
Take a minute to take some notes: What kind of color palette does Magritte use in The Human Condition (above)? For example, analogous, split-complimentary, complimentary, or triadic - or a unique combination?
Trichromatic Theory (a.k.a. the Young Hemholtz theory)
According to this theory, there are three kinds of cones that are uniquely suited to detect a certain range of wavelengths. That means we can only see three colors, right? Not at all (obviously)!!! We perceive the colorful world by rates of response in these 3 cones.
This theory has been verified - we have 3 types of cones and each responds to a different range of wavelengths.
Here is an example of how we may be able to distinguish colors according to the trichromatic theory:
Patterns of Activation: 450 nm (blue) may excite:
- Short: 65% of maximum response rate
- Medium: 40% of maximum response rate
- Long: 10% of maximum response rate
Patterns of Activation: 460 nm (blue a little closer to green) may excite
- Short: 65% of maximum response rate
- Medium: 50% of maximum response rate
- Long: 10% of maximum response rate
Patterns of Activation: 510 nm (orangey-red) may excite
- Short: 5% of maximum response rate
- Medium: 15% of maximum response rate
- Long: 60% of maximum response rate
<<Little known fact: It was Thomas Young of the Young-Hemholtz theory that deciphered the Rosetta Stone!!!>>
Opponent-Process Theory
According to this theory, we perceive color in terms of paired opposites. According to this theory know that photoreceptors form opposing color pairs such as red/green or blue/yellow. Activation of one actually inhibits activation of the other. This may explain why we don't commonly experience"greenish red" or "blueish yellow."
TED ED color: Color Theory and exercises
Links to an external site.
Many Psychology of Art students are very interested in color associations with emotions. We do associate certain colors with different emotions.Theories of Color Associations represent the idea that certain colors trigger emotional and cognitive responses. Often, these responses reflect our interactions with nature but may also be associated with cultural ideas such as myths. Below is a synopsis from Malchiodi (2007).
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RED |
Warmth, love, passion, birth, heat, life Blood, fire, wounds, anger |
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ORANGE |
Harvest, warmth, energy, power, fire, misfortune |
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YELLOW |
Sun, light, warmth, wisdom, intuition, hope, energy, riches, masculinity |
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GREEN |
Earth, fertility, vegetation, nature, growth, envy, overprotectiveness, creativity |
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BLUE |
Sky, water, sea, heaven, spirituality, relaxation, calm, nourishing, loyalty |
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VIOLET |
Royalty, spirituality, wealth, authority, death, imagination, attention, excitement, paranoia, persecution |
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WHITE |
Light, virginity, purity, moon, timelessness, resurrection, clarity, loss, enlightenment, creativity |
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BROWN |
Fertility, soil, sorrow, roots, excrement, dirt, worthlessness, new beginnings |
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BLACK |
Darkness, emptiness, mystery, beginning, unconsciousness, depression, loss, death |
Take a minute to take some notes: What psychological properties does Magritte's palette suggest to you? Would the image be just as effective with different hues?