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Past Test Questions from Applied Colorimetry (1993-1998)

1. The following figure represents a page from the Munsell Book of Color, 5Y. Draw a line of constant chroma and a line of constant saturation (2). Which line is more representative of the color change of a uniform pigmented ball that is spot illuminated (1)? Draw these two lines on a chromaticity diagram (2).

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2. Make a graph of the Sc functions for CIE94 and CMC color difference equations (2). Be sure to label your axes.

3. Define brightness according to the CIE Lighting Vocabulary or ASTM E284 (1).

4. The following is a diagram of a visual colorimeter in which fields A, B, and C are independently controlled.

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(A) Field C is set to 0 cd/m2. Field A is a broadband green filtered tungsten source. Field B is a mixture of three monochromatic lights. Can fields A and B be made to match for a CIE standard observer? How do you know? (2)

(B) Field C is set to 0 cd/m2. Field A is a tungsten source. Field B is a mixture of three monochromatic lights. Fields A and B are adjusted to match in chromaticity and luminance for the 1931 observer. Will the two fields match for the 1964 observer? Why or why not? (2)

(C) Field C is a blue filtered tungsten (similar in chromaticity to D65) set to 0 cd/m2. Field A is a tungsten source at 100 cd/m2. Field B is a mixture of three monochromatic lights. Fields A and B are adjusted to match in color for you. Estimate a color name for these two fields (1).

As the luminance of field C is raised to 200 cd/m2, will fields A and B continue to match? Why? (2)

Will fields A and B continue to have the same color name. If not, estimate their new color name (1).

(D) Field C is set to 0 cd/m2. Field A is a tungsten source. Field B is a mixture of three monochromatic lights. The two fields subtend a 10° field of view. Fields A and B are adjusted to match in chromaticity and luminance for the 1964 observer. By coincidence, the two fields also match for you. Will they continue to match to you as their luminances are decreased? Why or why not? (2)

5. CIELAB can be considered a simple color appearance model. Explain how (2).

6. The following are CIELAB coordinates for two different color reproductions of a caucasian face using two different imaging technologies. Which technology do you think is better? Why? (2)

Ill. D50 Ill. A

System L* a* b* L* a* b*

A 70 20 20 71 24 24

B 68 22 22 69 22 19

7. The following are CIELAB coordinates of two pairs of colors consisting of a standard and batch. Which batch is a closer in color to its standard when viewed by a color-normal observer. (2)

Pair 1

L* a* b*

Standard 50 10 -7

Batch 52 11.5 -4

Pair 1

L* a* b*

Standard 65 8 70

Batch 66 9.2 74.1

8. CIELAB coordinates are calculated for an object illuminated by D65. Can CIELAB be used to predict the color of the object illuminated by A? How or how not? (2)

9. Describe a procedure to determine whether a color imaging system is an additive color imaging system (2)?

10. The following are a set of sensor responses. Estimate the matrix that converts their signals to color matching functions (1). (Write out the complete matrix equation)

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11. What is a parametric factor. List four. (2)

12. When a television is displaying an image, one perceives a full range of colors including black. The measured luminance of the black is the same as the luminance of the television when it is turned off. Yet, when the television is turned off, it has a gray appearance, not black. Why? (2)

13. What CIE geometry will yield the largest color gamut for a glossy paint? Why? (2)

14. You are a colorist in charge of color matching automotive interiors. Should you be concerned that you use D65 in your calculations and a fluorescent daylight simulator in your light booth? Why or why not? (2)

15. The following equation is used in the Acme spectrophotometer for calibrating its scale of reflectance factor. What assumptions are made when using this equation? (2)

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16. A new CRT display has been developed with four primaries. What is it's peak white point chromaticity and luminance (2)?

Primary x y Y(Cd/m2)

B 0.200 0.100 10

C 0.160 0.500 35

G 0.400 .580 40

R 0.700 0.240 15

What are the advantages of this display compared with typical broadcast monitors? (1)

1. What has to be done in order for the CRT’s peak white luminance to match a perfect reflecting diffuser placed in the floor of the booth?

2. After the adjustment, will the two whites match in color if you look at them? Why or why not?

(Questions 3 and 4 ) Two fields are viewed by a color-normal observer:

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3. Field A: Luminance = 0.1 cd/m2, x=0.3, y=0.3

Field B: Luminance = 1000 cd/m2, x=0.2, y=0.6

Estimate a color name for fields A and B.

4. Field A: Luminance = 2000 cd/m2, x=0.4, y=0.4

Field B: Luminance = 400 cd/m2, x=0.4, y=0.4

Calculate the opponent signals sent to the brain for field B. Estimate a Munsell designation.

5. List the five principal hues of Munsell. List the principal hues of Hering. Why didn’t Munsell use Hering’s principal hues?

6. List differences between the CIE 2° and 10° observers.

7. What is the alychne?

8. According to the Fairman article, the chromaticity diagram is perpendicular to what tristimulus primary?

9. Based on the two-part Berns article, if Hardy had never existed, do you think there would have been an XYZ colorimetric system? Why?

10. You are interested in building a new color display. Having done a careful literature review, you discover the pioneering researches of Guild and Wright. You decide to use one of their primary sets. Which researches set will you use? Why?

11. What are the equations most commonly used to calculate tristimulus values for objects? Can colorfulness be calculated from these tristimulus values? Why or why not? (Include a definition for colorfulness.)

12. Define metamerism. Draw the spectra of a metameric pair encountered in color imaging. Label your axes and spectra.

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13. What is the difference between “basic” and “advanced” colorimetry?

14 and 15. In graphic arts, lighting is well standardized to a single spectral power distribution. They also have a standard set of inks that should be used for all process printing and proofing. (A proof is equivalent to a laboratory simulation of what the image will look like when printed on press.) Discuss the underlying theoretical bases for these standardization practices.

1. A metameric match is produced with a visual colorimeter for the 10° observer. Will the two stimuli continue to match as their luminance is reduced from 500 to 0.1 cd/m2? Why or why not? (5 points)

2. Define chroma according to the CIE Lighting Vocabulary or ASTM E284. Write an equation to predict chroma from spectral radiance and L, M, and S cone responses for a reflecting object. (5 points)

3. List three physiological reasons for variance among the observers used to define the 2° CIE standard observer. (5 points)

4. For color reproduction, should we match basic or relative appearance attributes? Why? (5 points)

3. You have been hired as a color scientist. You have to write a specification for light booths used for visual judgments. What is the specification? (5 points)

4. Make a graph of the SL functions for CIE94 and CMC color difference equations. Why are the SL functions for CIE94 and CMC so different? (5 points)

5. A spectral match will always yield a colorimetric match. Is the reverse true? Why or why not? (5 points)

6. If two objects have the same X,Y, and Z tristimulus values, will they have the L, M, and S retinal responses? (5 points)

7. Is it possible for two objects with the same CIELAB coordinates to match under all of the CIE recommended illuminants? How or how not? (5 points)

8. Why are all three-primary imaging systems color gamut limited? (5 points)

9. Describe a procedure to determine whether a color imaging system is an additive color imaging system? (5 points)

10. Tristimulus values can be defined in luminance units or in units relative to the perfect reflecting diffuser. Should there be the same choice for CIELAB coordinates? Why or why not? (5 points)

11. An original and reproduction have the same Y values but different chromaticities as shown in the following graph. Describe their difference in color appearance. (The x marks the white point.) (5 points)

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12. Describe a procedure for deriving a set of theoretical television camera spectral sensitivities for a defined CRT display. (5 points)

13. You are given a detector and four filters (red, green, yellow, blue). You want to build a colorimeter that is as accurate as possible when measuring the tristimulus values (D65, 2° observer) of photographic color prints. Describe how you will accomplish this. Be as complete as possible. (10 points)

14. You have been hired at a company that manufactures custom automotive lacquer for car enthusiasts. Your customers only like antique automobiles so you only have to manufacture “solid colors” (that is, you can forget about metallic and pearlescent coatings). You have been asked to develop a system of color measurement and control rather than using visual assessments. Write out this system. Be as complete as possible. (30 points)

1. If two stimuli match in their “basic” colorimetry attributes, will they match in their “advanced” colorimetry attributes? Why or why not?

2. List assumptions associated with Grassmann’s laws?

3. List a total of five similarities and differences between the human visual system and broadcast television (within the context of this class!).

4. Because our retinal spectral sensitivities are highly overlapping, it is difficult to engineer most color reproduction systems. Why?

5. Write the equations for calculating tristimulus values for objects.

6. Give an example where the vonKries law fails.

7. Given two sets of color matching functions, each derived from different primaries. Can you tell which primary set would yield the largest color gamut? How?

8. When one goes to a store to buy a television set, the salesperson will quote luminance specifications. Why aren’t the specifications given in illuminance?

9. Why is the 10° different than the 2° color-matching functions?

10. Draw the spectra of a metameric pair encountered in color imaging. Label your axes and spectra.

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11. Define lightness.

12. In the paint, textiles, and plastics fields, there is very little concern for the choice of color-matching functions. For that matter, there is no interest in using Judd’s modification of V( |[pic][pic]## £[pic][pic][pic]{"ç– ¡ µ¡¶λ), despite it’s higher correlation to physiology. Why?

13. Define device independent color. Are Grassmann’s laws incorporated into device independent color?

Two fields are viewed by a color-normal observer:

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14. Field A: Luminance = 0.1 cd/m2, x=0.3, y=0.3

Field B: Luminance = 1000 cd/m2, x=0.2, y=0.6

Estimate a color name for fields A and B.

15 and 16. Field A: Luminance = 2000 cd/m2, x=0.4, y=0.4

Field B: Luminance = 1000 cd/m2, x=0.4, y=0.4

Calculate the opponent signals sent to the brain for field B.

Estimate a Munsell designation.

Why did Guild have more negative tristimulus values than Wright?

List differences between the 2° and 10° observer.

What is the alychne?

According to the Fairman article, the chromaticity diagram is perpendicular to what tristimulus primary?

List the 5 principle primaries of the Munsell system. List Hering’s primaries. Why didn’t Munsell use Hering’s primaries?

You are defining a system of color matching. What aspects of the primaries need to be standardized?

1. What is the difference between "basic" and "advanced" colorimetry?

2. Why does Grassmann's proportionality law fail?

3. List five similarities or differences between the human visual system and broadcast television (within the context of this class!).

4. What is the main advantage to having our retinal spectral sensitivities highly overlapping?

5. What does the abbreviation CIE stand for?

6. What is the von Kries law? (Use equations and words.)

7. Given two sets of color matching functions, each derived from different primaries. Can you tell which primary set would yield the largest color gamut? How?

8. You want to specify properties of the room lights to insure that there is sufficient light to read. Would the specification be one of illuminance or luminance? Why (in a few words)?

9. For a 2° field of view, why does the blue channel color matching function have more variance than the red or green channels?

10. Draw the spectra of a metameric pair. Label your axes.

[pic]

11. Define colorfulness.

12. Write an equation to estimate chroma from integral retinal responses.

13. A color matching experiment was performed by one observer. The apparatus used low luminance monochromatic lights as primaries. The maximum saturation method was used. The bipartite field was 15°. List five problems associated with using these color matching functions for color specification?

14. Why did the CIE transform the RGB color matching functions to XYZ color matching functions?

15. To define a color specification system based on color matching, what must be standardized?

1. List three physiological reasons for variance among the observers used to define the 2° CIE standard observer.

2. Spatial compression is commonly performed in imaging. It has been stated that compressing in a device-independent space is better than a device-dependent space. Does it matter which device-independent space is used? Which device-independent space would you use? Why?

3. List five parametric factors that affect color discrimination.

4. Define lightness according to the CIE Lighting Vocabulary. Write an equation to predict lightness from integrated cone responses.

5. Many color spaces are based on the unique hues of red, green, yellow, and blue. The Munsell system is based on five principal hues. What are they? Why did he use five instead of four?

6. Define color constancy. Define metamerism in terms of color constancy.

7. When a television is displaying an image, one perceives a full range of colors including black. The measured luminance of the black is the same as the luminance of the television when it is turned off. Yet, when the television is turned off, it has a gray appearance, not black. Why?

8. Why did the CIE develop a standardized matching system rather than a system based on physiology?

9. Why can a chromaticity diagram have any triangular shape?

10. Draw the spectrum locus of an imaging system with monochromatic primaries of R=450 nm, G=550 nm, and B=650 nm.

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11. Two imaging devices have very different color gamuts. A color consultant suggests gamut mapping using the x,y,Y space and maintaining lines of constant dominant wavelength to insure that hue will not change. Would you hire this consultant for color advice? Why or why not?

12. What is the purpose of the 13L* term in the CIELUV equation?

13. For additive imaging systems, there is a linear relationship between each primary's radiometric scalar and the tristimulus values for colors within the imaging system's gamut. Describe a simple experiment and analysis to determine whether an imaging system is an additive imaging system.

14. A projection display has the following relationship between digital counts and luminance for each channel. Is this display an additive system? Why or why not?

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15. What CIE geometry will yield the largest color gamut for automotive coatings? Why?

16. You are a colorist in charge of color matching textiles. Should you be concerned that you use D65 in your calculations and a fluorescent daylight simulator in your light booth?

17. Describe the development of the CIELAB equation and color difference formula.

18. What color is X=67, Y=40, Z=13?

19. What is the main deficiency in CIELAB that CIE94 corrects? How does it accomplish the correction?

20. Develop a color space and color difference equation that has a physiological basis and good performance for setting industrial tolerances.

Two fields are viewed by a color-normal observer:

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1. (2) Field A: Luminance = 0.1 cd/m2 CCT = 2500K

Field B: Luminance = 1000 cd/m2 CCT = 6500K

Circle one.

Field A will appear: Field B will appear:

A. Yellow A. Yellow

B. Blue B. Blue

C. Gray C. Gray

D. White D. White

E. Black E. Black

2. (2) Field A: Luminance = 1000 CCT = 5000K

Field B: Luminance = 700 CCT = 20,000K

Circle one.

Field A will appear: Field B will appear:

A. Brown A. Brown

B. Blue B. Blue

C. Yellow C. Yellow

D. Bluish gray D. Bluish gray

E. White E. White

3. (2) A Munsell sample of Hue=10G, Value=6, and Chroma=10 is viewed under source C at an illuminance of 500 lux. It is then viewed under an increased illuminance of 1500 lux. Circle which appearance attributes have remained largely unchanged.

A. hue B. brightness C. lightness D. colorfulness E. chroma

4. (3) Two lamps with the same correlated color temperature of 5500K are used to photograph a scene. The first has a general color rendering index of 70. The second has a general color rendering index of 95. Which photograph will have better color quality? Why?

5. (3) The following are three plots of fluorescent sources (normalized spectral radiance vs. wavelength). Label the spectra with the highest and lowest CCT. Draw the spectral responsivities of a two detector color temperture meter optimized for fluorescent sources.

[pic][pic] [pic]

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6. (2) Two televisions are viewed side by side. Television "A" has a peak white luminance of 50 cd/m2 while television "B" has a peak white luminance of 100 cd/m2. Both televisions have the same relative spectral radiances for their primaries. Televisions have controls that vary "brightness," "saturation," and "hue" (color balance). Can these controls be adjusted to make the two televisions match in color appearance? How?

7. (2) Define metamerism using spectral-based equations.

8. (2) Define color constancy.

9. (3) How would you test a CCD camera to determine whether it has a linear photometric response?

10. (3) To measure the color attributes of materials with different gloss in order to get the best correlation to visual judgment when viewed in sunlight, which CIE geometry would you use? Why?

11. (2) The following geometry for a spectrophotometer best measures what properties of materials?

[pic]

A. hue, brightness, colorfulness

B. gloss

C. luminance factor

D. hue, chroma, lightness

12. (3) An integrating sphere spectrophotometer with polychromatic illumination has a dark current of 2 milliamps. The detector reads 200 milliamps with a white tile in the reflectance port. The reading of a filter placed between the sphere and the source with the white tile still in the reflectance port is 40 milliamps. Calculate the filter's transmittance.

13. (2) What evidence led Hering to propose the opponent theory of color vision?

14. (2) List two examples of metameric pairs associated with color imaging.

15. (3) Develop a model of color vision starting from spectral data and ending with the perceptual attribute of lightness. Be as complete as possible (including assumptions).

1. Will a photographic film accurately record the color of a metameric pair (1)? Why or why not (2).

2. List two color imaging systems that have benefited from the understanding of the human visual system's spatial color processing (2).

3. Why does an ink-jet printer using glossy paper generate a larger color gamut than the same printer using mat paper (2)?

4. What CIE geometry best correlates with visual observations of materials illuminated outside on a cloudy day (1)?

5. How can an integrating sphere spectrophotometer be used to measure diffuse transmittance (2)?

6. What CIE illuminant best approximates cool-white fluorescent light (1)?

7. Do rods and cones share similar neural pathways to the brain (1)?

8. Why is the CIE 1964 observer different than the CIE 1931 observer (2)?

9. Why did the CIE technical committee TC 1-29 reject the CMC equation (2)?

10. What features of CMC and CIE94 (TC 1-29 equation) are approximately the same (1)? What features are different (1)?

11. Why can CIELAB be considered a color vision model(3)?

12. An image is scanned and digitized using a CCD-type desktop scanner. It is then displayed on a CRT. The image looks very dark. What might have caused this (1)? How can this be corrected so that this doesn't keep occurring (1)?

13. An imaging system has the following primaries. Draw the color matching functions that would result if you used this system to repeat the experiments of Wright and Guild (3). Be sure to label your axes.

Primary x y Y(Cd/m2)

1 1.000 0.000 0

2 0.000 0.000 0

3 0.000 1.000 10

14. What perceptual attributes are most changed with changes in scene luminance (2)?

15. A new CRT display has been developed with four primaries. What is it's peak white point (2)?

Primary x y Y(Cd/m2)

B 0.200 0.100 10

C 0.160 0.500 35

G 0.400 .580 40

R 0.700 0.240 15

16. A three channel display has a peak white point of 160 Cd/m2. Which CRT would be preferred by a typical consumer when this display and the four channel display described in question 15 are viewed side by side (1)? Why (1)?

17. How would you deal with implementing the 4-primary display in a current broadcasting system (3)?

18. A photographic transparency is viewed in a transparency viewer as shown below where the image does not fill the viewing surface. The chromaticities and luminance of the viewing background and image "white" are given below. Calculate the color of the image white using CIELAB (2). What color name would you give it (1)?

[pic]

Background: x=.32 y=.32 Y=85cd/m2 Image white: x=.40 y=.40 Y=70cd/m2

19. The photographic transparency from question 18 is now projected in a darkened room. Calculate the color of the image white using CIELAB (2). What color name would you give it (1)?

20. How would you evaluate the color quality of a color imaging system (4). Be as complete as possible.

Two fields are viewed by a color-normal observer:

[pic]

1. Field A: Luminance = 0.1 cd/m2 CCT = 6500K

Field B: Luminance = 1000 cd/m2 CCT = 3200K

Circle one.

Field A will appear: Field B will appear:

A. Yellow A. Yellow

B. Blue B. Blue

C. Gray C. Gray

D. White D. White

E. Black E. Black

2. Field A: Luminance = 70 CCT = 3500K

Field B: Luminance = 100 CCT = 7500K

Circle one.

Field A will appear: Field B will appear:

A. Yellow A. Yellow

B. Blue B. Blue

C. Gray C. Gray

D. White D. White

E. Black E. Black

3. Two filtered detectors, one blue and one red, are used to measure daylight sources. Complete the plot:

[pic]

4. A Munsell sample of Hue=5R, Value=6, and Chroma=12 is viewed under D65 at an illuminance of 500 lux. It is then viewed under an increased illuminance of 1000 lux. Circle which appearance attributes have remained unchanged.

A. hue B. brightness C. lightness D. colorfulness E. chroma F. saturation

5. Two televisions with the same phosphor types are viewed side by side. One's peak white has a luminance of 60 cd/m2 while the other has a peak white of 100 cd/m2. Which television looks better? Why?

6. Two lamps with the same correlated color temperature of 5500K are used to photograph a scene. The first has a general color rendering index of 80. The second has a general color rendering index of 95. Which photograph will have better color quality? (Circle one)

A. First B. Second

7. List the three groups of fluorsecent lamps and give an example of each type.

8. Define color constancy.

9. How would you test a desktop scanner to determine whether it has a linear photometric response?

10. To measure the color attributes of materials with different gloss in order to get the best correlation to visual judgment when viewed in our class room, which CIE geometry would you use? Why?

11. The following geometry for a spectrophotometer best measures what properties of materials?

[pic]

A. hue, brightness, colorfulness

B. gloss

C. luminance factor

D. hue, chroma, lightness

12. An integrating sphere spectrophotometer with polychromatic illumination has a dark current of 2 milliamps. The detector reads 200 milliamps with a white tile in the reflectance port. The reading of a filter placed between the sphere and the source with a white tile still in the reflectance port is 40 milliamps. Calculate the filter's transmittance.

13. Define the stage theory of color vision?

14. Define metamerism and discuss its importance in color reproduction

(3)1. Define saturation according to the International Lighting Vocabulary.

(3)2. Field B has chromaticities of x=0.60 y=0.30 and a luminance of 10 cd/m2. Field A has chromaticities of x=0.30 y=0.35 and luminances as shown in the table. Complete the table.

[pic] [pic]

|Field A |Color name |

| (cd/m2) | |

|1 | |

|100 | |

|1000 | |

(3)3. The CIE has been considering updating its method of calculating its color rendering index. A suggestion was made to use CIELUV. A KAAoACgAKAAoACgAKAAoA

CgAIAhAAAAIAABAACAEAAFQwAAESAAgCEAABAgAAEAAIAQAAEgAAAQIACAIQAAICAAAQAAgB

AAAAΔE*ab would be calculated between a test color viewed with a reference illuminant and a test illuminant with the same correlated color temperature. This is repeated for 8 test colors and the results averaged to yield a general index. The committee rejected CIELUV. List plausible reasons why.

(3)4. How would you measure diffuse transmittance using a spectrophotometer with a CIE recommended geometry?

(3)5. Why do all spectrophotometers that are used for colorimetry have white light illumination?

(3)6. A sample is made using an injection-molded plastic where it has two different surface attributes, textured and smooth. Draw the reflectance factor of each surface measured with the following geometries. You can choose its color.

[pic][pic]

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(3)7. List three physiological factors that contribute to color matching function variance.

(3)8. How do rods influence the 10° observer?

(3)9. Mathematically define a color match.

(3)10. Define spectral color reproduction and give an example where achieving spectral color reproduction would be much more desirable than achieving colorimetric color reproduction.

(6)11. The following are Wright and Guild's color matching function results. How would you analyze them to determine whether they are statistically the same or different.

[pic][pic]

(3)12. The XYZ system is based on imaginary primaries. Should the CIE abandon this system and return to a real RGB system based on real primaries? Why or why not.

(3)13. What are the differences between relative and absolute tristimulus values?

(3)14. Absolute tristimulus values are often used in modern color appearance models. Why?

(3)15. Define a colorimetric projective transformation. Why have colorimetrists found projective transformations so useful?

16. A new three tunable-laser projection display has been invented for a new cable television network.

[pic]

(1)A. What wavelengths would you tune each laser to? Why?

(1)B. What white point would you use for the display? Why?

(2)C. Assuming current television cameras meet NTSC specifications, could existing cameras be used for this new display? Why or why not?

(2)D. Describe how you would define a new camera for use with this new display that minimizes signal processing.

(3)17. Since u'v' is a uniform chromaticity scale diagram, wouldn't a Euclidean distance metric based on Yu'v' perform as well as CIELUV given that CIELUV is based on u'v'? Why or why not?

(3)18. Describe a visual experiment that would yield data effective for evaluating and deriving an improved color difference equation in comparison with the current CIE recommendations. Describe also how you would derive the equation from the data.

(3)19. Compare and contrast the CMC and TC1-29 color difference equations.

(3)20. Color reproduction is often defined in terms of analysis and synthesis stages. Define CIE colorimetry by these same terms.

(6)21. A computer graphics workstation is used to generate synthetic imagery for the next Star Wars movie. It has a CRT with a peak white point having chromaticities equal to D65 and a luminance of 50 cd/m2. The images will be written to movie film using a laser-based film recorder. You have been hired to consult with the company that manufactures the film recorder. They want the projected slides to have the same appearance (or better!) as the CRT images. They are currently optimizing three look-up tables to insure their slides are gray balanced and are sampling the full dynamic range of the film. What advise will you give them? Assume the movie projector uses a Xenon source with a CCT of 9000K and white image areas have a luminance of 250 cd/m2. (Help from Heloise: Don't stress out about the technology, focus on the colorimetry.)

1. Write a set of equations that could approximate the conversion from L, M, and S to Munsell hue, lightness, and chroma. (5 points)

2. According to the Fairman article, the chromaticity diagram is perpendicular to what tristimulus primary? (5 points)

3. List five causes of variability in color matching functions. (5 points)

4. Draw a sampling of color space that uses hue, lightness, and saturation. (5 points)

5. What is the relationship between chroma and saturation? (5 points)

6. What are the equations for calculating x, y, Y (lm/m2) from spectral irradiance? (5 points)

7. Describe an experiment that supports opponent color vision theory. (5 points)

8. Two image capture systems are proposed. In system A, the beam splitters transmit 50% of the light and reflect 50% of the light. A color filter is placed in front of each detector. In system B, dichroic beam splitters are used such that a detector receives either 400-500 nm, 500-600 nm, or 600-700 nm.

[pic]

8. Discuss the advantages and disadvantages of each camera. (5 points)

9. Assume the detector has a uniform spectral sensitivity with respect to wavelength. Draw the filter transmittances in each system that will lead to the best color accuracy. (5 points)

10. Define chromatic adaptation. (5 points)

11. Draw V(λ) and V'(λ).(5 points)

12. Guild defined a color matching "box" for use in industry. What is the definition? (5 points)

13. Here are three colored objects illuminated by D65.

A: Y = .5, x=0.4, y=0.5

B: Y = 0.3, x=0.4, y=0.5

C: Y = 0.2, x=0.4, y=0.5

Describe their differences using Munsell terminology. (5 points)

15.

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Field B has the following chromaticities and luminance: x=0.7, y=0.7, L=200 cd/m2. Field A is adjustable to any color you want. Can you make Field B appear black? How? (5 points)

16. Where's black on the chromaticity diagram? (5 points)

17. You are building a visual colorimeter to measure color-matching functions where a CRT display is used to generate red, green, and blue light. Describe the apparatus (use schematics if it helps), the experiment you will perform, and how you will generate XYZ color matching functions where one of the color matching functions is the 1924 luminous visual efficiency function. (20 points)

18. (3) The CIE/ASTM definition of lightness is:

19. (2) List two examples where defining stimuli by their hue, brightness, and colorfulness will give better correlation with visual judgments of color quality than hue, lightness, and chroma.

20. Two televisions have the same phosphors, gamma, and white point chromaticities. Television "A" has a peak luminance of 200 cd/m2 while television "B" has a peak luminance of 85 cd/m2. They both receive the identical program signals.

9. (3) Which television better reproduces the chroma of the original scene?

10. (3) Which television would you want to own? Why?

11. (3) Television "A" has a poor set up where the chromaticities of its black point (equivalent to 0 digital counts) are x=0.2, y=0.2. What color name would you give to image "blacks"?

21. (4) A German scientist, K. Richter, derived a chromaticity diagram that is a projective transformation of tristimulus space with the same uniformity of spacing as CIELAB for the Munsell Book of Color at Value = 5. List a total of four advantages and disadvantages of this chromaticity diagram in comparison to CIELAB.

22. (3) A room has two ceiling heights. Will the luminance of light fixtures installed in the ceiling that are measured from the floor be different? How?

23. (3) What industrial application was the "driving force" behind the CIE in developing colorimetry?

24. (2) List two important reasons why the x,y chromaticity diagram should not be used for setting industrial tolerances.

25. (3) List three of Grassmann's laws.

26. (2) Give two examples where Grassmann's laws often fail.

27. (3) A set of color-matching functions was derived by matching monochromatic lights with the primaries of 450 nm, 550 nm, and 650 nm. Draw a set of color-matching functions that would result from a color-normal observer performing the matching experiment. Be sure to label your axes.

28. (3) The color-matching experiment from question 10 is performed with the following conditions: 10° field of view, peak luminance of 1 cd/m2 when the three primaries are added together, and 100 color-normal observers selected from the Center for Imaging Science. Will the average of the CIS observers match the 1964 standard observer? Why or why not?

29. (5) A color-matching experiment is performed with the following primaries:

P1: x=0.2, y=0.4, P2: x=0.4, y=0.4, P3: x=0.4, y=0.2

Discuss the advantages and disadvantages of this set of primaries compared with the RGB primaries defined by the CIE in 1931.

30. (6) You are manufacturing roofing shingles that consist of colored stone granules glued onto asphalt. You want to develop an instrumental method of quality control. Write out the complete quality control specification.

31. (3) Whose color vision model was the basis of CIELAB?

32. (3) What is the ASTM E 308 method?

33. (5) Write a set of equations that estimate hue, chroma, and lightness from cone fundamentals, L, M, and S.

(3) Write the equation for CIE94.

34. (5) List five similarities or differences between CIE94 and CMC color-difference equations.

35. (3) Can optimized color tolerances be generated using only "pass" data? How?

36. (2) Which CIE geometry best correlates with visual evaluations performed in a typical light booth?

37. (3) How would you measure any haze that might be present in an automobile windshield?

38. (2) Define observer metamerism.

39. (5) It has been argued that acceptability tolerances are perceptibility tolerances scaled by a commercial factor. Describe an experiment to prove or disprove this argument.

(3) Why are colorimeters rarely used anymore to measure the color of materials?

(5) The following plot is the spectral sensitivities of a proposed colorimeter designed by a color "consultant". Can this instrument accurately measure the chromaticities and luminance of CRT displays? If yes, how? If no, why not?

[pic]

40. (3) According to the Fairman article, the chromaticity diagram is perpendicular to what tristimulus primary?

41. (3) A spectral match will always yield a colorimetric match. Is the reverse true? Why or why not?

42. (4) A CRT displays the following image:

[pic]

Field "A" has digital counts of 128, 128, and 128 and colorimetric coordinates: Y=20 cd/m2, x=0.31 and y=0.32. Field "B" has colorimetric coordinates of Y= 10 cd/m2, x=0.31, y=0.32. The display has a gamma of 1.0. The display is in a room without any lights on. Calculate the CIELAB coordinates of fields "A" and "B".

43. Write a set of equations that could approximate the conversion from L, M, and S to Munsell hue, lightness, and chroma. (5 points)

44. According to the Fairman article, the chromaticity diagram is perpendicular to what tristimulus primary? (5 points)

45. List five causes of variability in color matching functions. (5 points)

46. Draw a sampling of color space that uses hue, lightness, and saturation. (5 points)

47. What is the relationship between chroma and saturation? (5 points)

48. What are the equations for calculating x, y, Y (lm/m2) from spectral irradiance? (5 points)

49. Describe an experiment that supports opponent color vision theory. (5 points)

Two image capture systems are proposed. In system A, the beam splitters transmit 50% of the light and reflect 50% of the light. A color filter is placed in front of each detector. In system B, dichroic beam splitters are used such that a detector receives either 400-500 nm, 500-600 nm, or 600-700 nm.

[pic]

50. Discuss the advantages and disadvantages of each camera. (5 points)

51. Assume the detector has a uniform spectral sensitivity with respect to wavelength. Draw the filter transmittances in each system that will lead to the best color accuracy. (5 points)

52. Define chromatic adaptation. (5 points)

53. Draw VwAaAAECBgATAwsAGgABAgYAFAMLABoAAQIGABUDCwAaAAECBgAWAwsA

GgABAgYAFwMLABoAAQIGABgDCwAa(l) and V'(l).(5 points)

54. Guild defined a color matching "box" for use in industry. What is the definition? (5 points)

55. Here are three colored objects illuminated by D65.

A: Y = .5, x=0.4, y=0.5

B: Y = 0.3, x=0.4, y=0.5

C: Y = 0.2, x=0.4, y=0.5

Describe their differences using Munsell terminology. (5 points)

56.

[pic]

Field B has the following chromaticities and luminance: x=0.7, y=0.7, L=200 cd/m2. Field A is adjustable to any color you want. Can you make Field B appear black? How? (5 points)

57. Where's black on the chromaticity diagram? (5 points)

58. You are building a visual colorimeter to measure color-matching functions where a CRT display is used to generate red, green, and blue light. Describe the apparatus (use schematics if it helps), the experiment you will perform, and how you will generate XYZ color matching functions where one of the color matching functions is the 1924 luminous visual efficiency function. (20 points)

58. (3) The CIE/ASTM definition of lightness is:

59. (2) List two examples where defining stimuli by their hue, brightness, and colorfulness will give better correlation with visual judgments of color quality than hue, lightness, and chroma.

60. Two televisions have the same phosphors, gamma, and white point chromaticities. Television "A" has a peak luminance of 200 cd/m2 while television "B" has a peak luminance of 85 cd/m2. They both receive the identical program signals.

61. (3) Which television better reproduces the chroma of the original scene?

62. (3) Which television would you want to own? Why?

63. (3) Television "A" has a poor set up where the chromaticities of its black point (equivalent to 0 digital counts) are x=0.2, y=0.2. What color name would you give to image "blacks"?

64. (4) A German scientist, K. Richter, derived a chromaticity diagram that is a projective transformation of tristimulus space with the same uniformity of spacing as CIELAB for the Munsell Book of Color at Value = 5. List a total of four advantages and disadvantages of this chromaticity diagram in comparison to CIELAB.

65. (3) A room has two ceiling heights. Will the luminance of light fixtures installed in the ceiling that are measured from the floor be different? How?

66. (3) What industrial application was the "driving force" behind the CIE in developing colorimetry?

67. (2) List two important reasons why the x,y chromaticity diagram should not be used for setting industrial tolerances.

68. (3) List three of Grassmann's laws.

69. (2) Give two examples where Grassmann's laws often fail.

70. (3) A set of color-matching functions was derived by matching monochromatic lights with the primaries of 450 nm, 550 nm, and 650 nm. Draw a set of color-matching functions that would result from a color-normal observer performing the matching experiment. Be sure to label your axes.

71. (3) The color-matching experiment from question 10 is performed with the following conditions: 10° field of view, peak luminance of 1 cd/m2 when the three primaries are added together, and 100 color-normal observers selected from the Center for Imaging Science. Will the average of the CIS observers match the 1964 standard observer? Why or why not?

72. (5) A color-matching experiment is performed with the following primaries:

P1: x=0.2, y=0.4, P2: x=0.4, y=0.4, P3: x=0.4, y=0.2

Discuss the advantages and disadvantages of this set of primaries compared with the RGB primaries defined by the CIE in 1931.

73. (6) You are manufacturing roofing shingles that consist of colored stone granules glued onto asphalt. You want to develop an instrumental method of quality control. Write out the complete quality control specification.

74. (3) Whose color vision model was the basis of CIELAB?

75. (3) What is the ASTM E 308 method?

76. (5) Write a set of equations that estimate hue, chroma, and lightness from cone fundamentals, L, M, and S.

77. Write the equation for CIE94.

78. (5) List five similarities or differences between CIE94 and CMC color-difference equations.

79. (3) Can optimized color tolerances be generated using only "pass" data? How?

80. (2) Which CIE geometry best correlates with visual evaluations performed in a typical light booth?

81. (3) How would you measure any haze that might be present in an automobile windshield?

82. (2) Define observer metamerism.

83. (5) It has been argued that acceptability tolerances are perceptibility tolerances scaled by a commercial factor. Describe an experiment to prove or disprove this argument.

84. Why are colorimeters rarely used anymore to measure the color of materials?

85. The following plot is the spectral sensitivities of a proposed colorimeter designed by a color "consultant". Can this instrument accurately measure the chromaticities and luminance of CRT displays? If yes, how? If no, why not?

[pic]

86. (3) According to the Fairman article, the chromaticity diagram is perpendicular to what tristimulus primary?

87. (3) A spectral match will always yield a colorimetric match. Is the reverse true? Why or why not?

88. (4) A CRT displays the following image:

[pic]

Field "A" has digital counts of 128, 128, and 128 and colorimetric coordinates: Y=20 cd/m2, x=0.31 and y=0.32. Field "B" has colorimetric coordinates of Y= 10 cd/m2, x=0.31, y=0.32. The display has a gamma of 1.0. The display is in a room without any lights on. Calculate the CIELAB coordinates of fields "A" and "B".

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