Chapter 1 – Introduction to Color Study
1. What is the difference between direct light and reflected light? Give examples of each.
Direct light travels from the source to the destination without being interrupted while reflected light is the light produced when the direct light bounces off a material. One example of direct light is the sunlight while reflection from the mirror is an example of reflected light (Young, Freedman & Ford, pp. 1080).
2. Describe the cause of color, the means used to generate it, and the effect.
Light consists of a spectrum of light wavelengths which have a representative color; thus, upon reaching the retina of the eye, a particular color is seen. When light reaches a prism, the colors become dispersed producing the colors red, orange, yellow, green, blue and violet. White is produced when all of these wavelengths reach the retina at the same time; On the contrary, black is produced when none of these wavelengths reaches the retina (“the Electromagnetic and Visible Spectra”).
3. What are some reasons why colors can be unstable?
There are two reasons for the instability of colors: (1) relationship between the colorant and the lighting and (2) the arrangement of colors. Changes in the lighting can greatly influence the instability of the color because it affects the subtractive colors in terms of the hues and brightness while the arrangement of colors affects the hue, value, and saturation of the color when two or more colors are used together (Holtzschue).
4. What is color temperature?
Color temperature is the color produced by a black body when it reaches the temperature above absolute zero (Young, Freedman & Ford).
5. How does the PANTONE color system work?
The pantone color system is the standardization of the colors and naming these colors using numbers. The standardization can help manufacturers from different location to choose a particular color from the numbered colors to prevent color changes during processing of products.
6. What are the three attributes that every color possesses?
The three attributes that every color possess are hue, value, and intensity (Young, Freedman & Ford)
The Nature of Light
1. What is light? Sketch a light wave and label the wavelength.
Light or visible light is a type of an electromagnetic wave which can stimulate the retina found in human’s eyes.
2. How are electromagnetic waves and sound waves different? Discuss what causes the wave oscillations, the wave speeds, the medium required (if any), the range of frequencies, and whether the waves are transverse or longitudinal.
Electromagnetic wave is different from sound waves because the former is capable of transmitting energy through a vacuum. EM waves are transverse waves produced by the vibration of charges particles and its speed of light is always constant. In addition, the relationship of wavelength and frequency is inversely proportional. On the other hand, sound wave is a longitudinal wave which requires a media for it to travel, its frequency determines the pitch of the sound, and its amplitude determines its volume (Young, Freedman & Ford)
3. What are the different types of EM waves found in the electromagnetic spectrum?
The waves found in the electromagnetic spectrum are radio waves, microwaves, infrared light waves, visible light waves, ultraviolet light waves, x-rays, and gamma waves.
4. What is the range of wavelengths of visible light?
The range of wavelengths of visible light is approximately 700 nm to 400 nm.
5. For the following EM waves, either their wavelength or frequency is specified. You are to first calculate the missing quantity (frequency or wavelength) using the equation c = fλ, where the speed of light c = 3*108 m/s. Then look up the wave in the EM spectrum table and state which type of wave it is (radio, infrared, microwave, visible light, ultraviolet, x-ray, gamma ray). If the wave is visible light, state what color it is. Note that 1 nm = 10-9 m, 1 mm = 10-3 m, and 1 μm = 10-6 m.
a) 450 nm f = 6.67*1014 Hz visible (blue/indigo)
b) 5.0*1014 Hz λ = 6.00*10-7 m = 600 nm (yellow/orange)
c) 4.7 m f = 6.38*107 Hz (radio)
d) 3.3*1019 Hz λ = 9.09*10-12 m (gamma rays)
e) 2 mm f = 1.5*1011 Hz (microwaves)
f) 2.5 μm f = 1.2*1014 (infrared)
g) 6.1*1015 Hz λ = 4.91*10-8 m (ultraviolet)
6. What is a photon?
Photon is a tiny particle of light which carries energy proportional to the frequency of the radiation but has a rest mass of zero
7. What is the law of reflection?
The law of reflection states that the angle of reflection and the angle of incidence is equal. Additionally, it also states that the incident ray, the reflected ray, and the normal ray (ray to the surface of the mirror) all lie in the same plane.
8. What is refraction?
Refraction refers to the bending process of a wave as it enters a medium which changes its speed.
9. What is dispersion?
Dispersion is the phenomenon where light wave is separated according to its wavelength (color) as it passes through an object.
10. What causes the rainbow?
Rainbows are caused by the reflection, refraction, and the dispersion of light found in water droplets.
Chapter 2 – A Little Light on the Subject
1. What are common sources of light?
The common sources of light include sun, stars, moon, artificial light (candles, fires, and oil lamps, lasers), electric light (light bulb, neon light, and fluorescent tubes), infrared, and ultraviolet lights.
2. What are the pure hues of light?
The pure hues of light are red, green, and blue-violet
3. Does additive color apply to direct or reflected light? What about subtractive color?
Additive color apply to direct light while subtractive color apply to reflected light.
4. What factors influence color in the illuminant mode (direct light) of vision?
The factors that influence color in the illuminant mode of vision are gloss, texture, luster, surface, scene, and background.
5. What factors influence color in the object mode (reflected light) of vision?
The factors that influence color in the object mode of vision are source, intensity, background, and scene.
6. How does mixing colored light differ from mixing colored paints?
The primary colors of paint are magenta, yellow, cyan while the primary colors of light are red, green, and violet. Thus, the mixing of the paint result which make up the secondary colors of paint are the primary colors of light. Additionally, mixing of paint can produce any color but the mixing of light can only produce fixed colors.
7. What are the primary additive colors? The primary subtractive colors?
The primary additive colors are red, green, and blue while the primary subtractive colors are cyan, magenta, yellow, and black.
8. The surface of the sun is 5800 K.
a) Use Wien’s Displacement Law to calculate the peak wavelength emitted.
Use λmax = (2.899*10-3 mK)/T. Answer: 499.6 nm
b) What color is this? (Look up the wavelength on a spectrum.) light blue
9. Average human body temperature is 98.6 °F.
Use TK = (5/9)(TF – 32) + 273
a) Convert this to degrees Kelvin. 310 K
b) Calculate the peak wavelength emitted by a human. Use Wien’s Displacement Law. 9348 nm
c) In what portion of the electromagnetic spectrum is this wavelength? Would you be able to see this with your eyes? If not, how could you detect this radiation? infrared
10. How does an incandescent lamp work?
Incandescent lamp contains tungsten filament which produces a light when heated at a particular temperature upon the passage of electric current.
11. How does a fluorescent lamp work?
Fluorescent lamp emits photons when the ionizing mercury vapor found in the glass tube excites the electrons causing it to convert UV light into visible light using the coating of the tube which is made up of phosphor “The Fluorescent Lamp”.
12. How does an LED lamp work?
Led lamp emits light through electroluminescence which occurs in a semiconductor material. Electroluminescence occur when an electric current passes through a light emitting material and fill electron holes “LEDs and OLEDs”.
13. What is metamerism? What could cause it?
Metamerism is the phenomenon where there is an observed color change when the colors are viewed under different sources of light. The metamerism is caused by differences in the sources of light.
14. White light passes through a red filter. What color is seen? Why?
Red is seen because only red light is allowed to pass through.
15. Green light passes through a red filter. What color is seen? Why?
Black because only red light is allowed to pass through, thus green is absorbed by the filter.
16. Green light passes through a cyan filter. What color is seen? Why?
Green because cyan consists of green and blue light. Since the light is green, it will be allowed to pass through the filter.
Chapter 3 – The Human Element
1. Identify the following parts of the eye. Explain the function of each.
Retina is responsible for transmiting light into chemicals and electrical pulses; Choroid provides blood supply and nutrition to the eye; Fovea provides the clearest vision of the eye; optic nerve transfers visual information received by the retina to the brain; Sclera provides structure and safety in the inner parts of the eye; Vitreous humor helps hold the shape of the eye; Lens is responsible of focuseing the light entering the pupil; Aqueous humor allows the maintenance of the eye’s shape; Pupil is the hole that takes in light; Iris contains pigment that gives the eye its characterictic color; and cornea protects the eye from outer elements.
2. What is a visual threshold?
Visual threshold refers to the minimum light intensity that evokes a visual sensation
3. What is an interval?
Interval is the term used to identify the conical image space bounded by the two focal lines of a lens.
Chapter 4 – The Vocabulary of Color
1. What is hue?
Hue refers to the name of the color labeled in the color wheel.
2. How is hue expressed in different color models: RGB (red/green/blue), CMYK (cyan/magenta/yellow/black), Hue/Saturation/Value (HSV)?
Hue is expressed in the RGB model is additive while the CMYK model is subtractive. On the other hand, in the HSV color model, hue is expressed in terms of shade and brightness.
3. What are primary, secondary, and intermediate colors? Give examples in the RGB and CMYK systems.
The primary colors in the RGB system are red, green, and blue while the secondary colors are yellow, magenta, and cyan. The intermediate color of the RGB system is white. On the other hand, the primary colors of the CMYK system are cyan, magenta, yellow, and black. The secondary colors are red, green, and blue.
4. What are complementary colors? Give examples.
Complementary colors are the colors which are opposite each other on the color wheel. Some of the examples include red and green, violet and yellow, and blue and orange.
5. What are black, white, and gray? How are these produced in RGB, CMYK, and HSV?
Black, white, and gray are neutral colors. White is produced when the primary colors are combined in the RGB system while black is produced when the primary colors are combined in the CMYK system. Lastly, gray is produced when all of the colors are combined in the HSV system.
6. What is value?
Value refers to the darkness or lightness of a color.
7. How can different values be produced?
High-value colors can be produced when the color is light while low-value colors are produced when the color is made dark.
8. What is saturation?
Saturation is the term used to determine the intensity of colors in an image.
9. Explain how additive color mixing works in the RGB model with direct light.
Additive colors using direct light works with direct light by combining two or more colors and creating a lighter color which is close to white.
10. Explain how subtractive mixing works in the CMYK model for print with reflected light.
Subtractive mixing using the CMYK model for reflected light works by adding color which results to a darker color and eventually black. The color displayed or seen by the naked eye depends on the color not absorbed by the pigment
11. Describe how computer monitors produce color. (Hint: additive mixing.)
Computer monitors uses red, green, and blue dots which stimulate the retina by adding or blending the light of the dots together creating a composite color.
12. Describe how a video projector produces color. (Hint: additive mixing, reflection off a white screen.)
Video projector produces color by driving three small but very close red, green, and blue light sources which seems to be indistinguishable at a distance. The proximity of the light sources tricks the eye to give a solid color. The pixels can be arranged in the screen to give and form a particular image.
13. Describe how print inks produce color. (Hint: subtractive mixing.)
Print inks produce color by using color inks as filters which can subtract portions of the white light that strikes the image on paper to be able to produce other colors. The primary colors of inks are cyan, magenta, yellow, and black.
Works Cited
Holtzschue, L. (2012). Understanding Color: An Introduction for Designers. New York, New York: John Wiley & Sons, Inc.
“LEDs and OLEDs.” Edison Tech Center: The Miracle of Electricity and Engineering. 2013. Web. 01 May 2016.
“the Electromagnetic and Visible Spectra.” the Physics Classroom. 2016. Web. 01 May. 2016.
“The Fluorescent Lamp.” Edison Tech Center: The Miracle of Electricity and Engineering. 2013. Web. 01 May 2016.
Young, H.D., Freedman, R.A., & Ford, A.L. (2012). Sears and Zemansky’s University Physics: With Modern Physics. Boston, US: Addison-Wesley.
