Chapter 2. Context Influences Color

Learning Objectives

color constancy
perceiving an object as having the same color when viewed under changing illumination
retina
light-sensitive inner surface of the eye, containing rods and cones
color contrast
difference between the color of one object and the surrounding objects
visual cortex
area in the occipital lobes that receives and processes information from the eyes
perception
organizing and interpreting information from the senses to understand its meaning
wavelength
the width of a light wave, measured as the distance between peaks; related to the hue (perceived color) of a light
Context Influences Color
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There are two photos of the same dress. A blue and black dress is on the left. The same dress is on the right but has a filter applied which makes it look white and gold.
AP Images/Ale Ventura/PhotoAlto
Learning Objectives:

Understand the importance of context in color perception.

Describe the difference between color contrast and color constancy.

Review

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Red tomatoes with a yellow lemon in the middle
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1. Our perception of the color of an object always depends on the surrounding colors.

2.0.1 Review

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Red tomatoes with a yellow lemon in the middle
Garry Gay/Getty Images

2. The neural connections within the retina of the eye and the visual cortex of the brain are designed to evaluate the light reflected from any object in comparison to the surrounding objects.

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Red tomatoes with a yellow lemon in the middle
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3. This comparison produces color contrast, and our perception of an object's color changes as the background color changes.

2.0.3 Review

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Red tomatoes with a yellow lemon in the middle. Transparent yellow and blue bands of color are overlayed on the photo but the tomatoes still seem to be red and the lemon still seems to be yellow. Various fruit varying by color. Transparent red and green bands of color are overlayed on the photo but the colors of the fruit still seem to be the same.
Garry Gay/Getty Images
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4. But this comparison also produces color constancy — allowing the perceived color of a familiar object to remain roughly the same even when the lighting changes.

2.0.4 Review

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Red tomatoes with a yellow lemon in the middle. Transparent yellow and blue bands of color are overlayed on the photo but the tomatoes still seem to be red and the lemon still seems to be yellow. Various fruit varying by color. Transparent red and green bands of color are overlayed on the photo but the colors of the fruit still seem to be the same.
Garry Gay/Getty Images
Africa Studio/Shutterstock

5. For example, if we are viewing a yellow lemon, we will continue to perceive the lemon as yellow even if the light falling on the lemon changes from white to blue or green, thus changing the wavelength of the light being reflected from the lemon's surface.

Practice 1: Demonstrating Color Contrast

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Practice 1: Demonstrating Color Contrast

Use the buttons to vary the color of the circles and squares, and observe how the background color of the squares influences your perception of the color of the circles.

The principle of color contrast predicts that the perceived color of an object will change when the surrounding color changes. Try it!

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Circles color:

Squares color:

Practice 2: Demonstrating Color Constancy

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Practice 2: Demonstrating Color Constancy

Use the buttons to vary the color of the beam of light, and observe the color of the fruit.

Red tomatoes with a yellow lemon in the middle. Lamp above shines a transparent colored light beam down over image. Light beam color changes with options A, B, C and D. A is yellow, B is green, C is purple, D is red.
Garry Gay/Getty Images

The principle of color constancy predicts that the perceived color of an object relative to other surrounding objects will not change when the color of the overhead lighting changes. Try it!

Notice that the actual light reflected from the fruit changes as the color of the light beam changes. But, we still perceive the lemon as "yellow" and the tomato as "red."

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Light beam color:

Quiz 1

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Quiz 1

Study the illustration and select an answer to the question. Then, select the CHECK ANSWER button.

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Try to answer the question again.
In the illustration above, the perceived color of the thin green bar demonstrates the principle of:
illusory color
color constancy
color contrast

Quiz 2

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Quiz 2

Match the principles with the examples by dragging each term to the appropriate rectangle. When all the terms have been placed, select the CHECK ANSWER button.

Four different colored squares: black, white, orange and blue. Within each square is a smaller yellow square. Two of the same photo of different colored fruit. The photo on the left has a green filter over it and the photo on the right has a red filter over it. Two of the same photo of a girl holding up different colors of paper. The photo on the left has a green filter over it and the photo on the right has a red filter over it. Two circles are in the middle of a large rectangle. The circle on the left is blue and the circle on the right is green. The rectangle has thin puple and orange vertical lines going through it, with the purple lines going over the blue circle and the orange lines going over the green circle. There is a small blue rectangle connecting the circles, over top of the vertical lines.
In Green/Shutterstock
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Select the NEXT button and move to the Conclusion.
Perhaps you should go back to review the principles of color context.
color contrast
color contrast
color constancy
color constancy

Conclusion

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two photos of the same dress. One is blue and black and one has a filter applied which makes it look white and gold
AP Images/Ale Ventura/PhotoAlto
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