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CIELab

100

What is the range of L* a* and b*?

L* 0-100 

a* (-) infinity - (+) infinity

b* (-) infinity - (+) infinity

200

+ a* represents ________

 -a* represents_________

a*

+Red, -Green

b*

+ yellow, -blue  

300

Which CIELab variable(s) would you use to evaluate the reproduction of tones? 

L*

400

What would be the CIELab Notation for a pure black 

L*= 0

a* = 0 

b* = 0

500

Please write/say the equations to solve Hue Angle, and Chroma for the following CIELab values. (Don’t solve) 

L* = 22   a*= 35   b*=8 

hue angle = tan-1(8/35) 

chroma = SQRT (35^2 + 8^2) or SQRT (1225+64)

Chroma diagram

100

T/F 

XYZ are chromaticity coordinates  

False 

200

What are the variables that represent the standard observer 

xbar, ybar, zbar 

300

On the chromaticity diagram, the outer edge is called the _______. The ________ is where all the chromaticities for a BBR will plot, and along the __________ are colors that cannot be reproduced with monochromatic light. 

Spectral locus, planckian locus, line of purples 

400

Which of variables that we have learned about would you use to plot a color gamut? Do we need all of them? 

Chromaticity coordinates. No.( which ones?) 

500

tristimulus values and chromaticity coordinates both have a variable using “X.” State the equations to solve for both of these “X” variables. (2 separate equations) 

X= kSUM(Sλ*Rλ*xbar)

x = X/(X+Y+Z)

Color Management

100

T/F The goal of color management is for all devices to have the same color gamut 

False 

200

Name the three common color spaces spoken about in lecture 

Prophoto RGB 

Adobe 1998

sRGB 

300

T/F a densitometer is not an adequate measurement tool for providing color information 

True 

400

When speaking about adequate editing conditions, why is middle gray recommended for walls and monitor backgrounds 

It helps avoid simultaneous contrast 

500

Give an example of the calibration and characterization of the same device (try to be creative and not use the scale example)  

Calibration -bringing something to a known state 

Characterization - knowing the characteristics of a device and adjusting to them 

Random

100

T/F Mobile operating systems do not support ICC profiles 

True 

200

Which of the following are not necessary for seeing color? 

A light source 

A measurement device 

An observer 

An objects reflectance 

Measurement device 

An objects reflectance 

(This question was worked differently with these as incorrect options^) 

300

An object that is blue will most likely be reflecting the most in what nanometer or nanometer range? 

400nm or anything around there 

400

The exact dimensions of the color checker were made to ____________? 

fill/fit 35mm film 

500

You’re hired by a print house that asks you to determine if their printer has a color cast. Describe what you would do? (She’s not going to ask this but I want you guys to exercise critical thinking and not just copy paste definition answering) 

I would print a black and white image that is set to grayscale in printing settings (not just converted to black and white) to make sure that my monitor is not influencing the process. I would then print this same image on multiple types of paper using the printer I’m testing. I would then use a spectrophotometer (or colorimeter) to take readings in the same spots on each print and compare the data. I would look to if the a* and b* CONSISTENTLY trend in a certain direction.