CIELab
What is the range of L* a* and b*?
L* 0-100
a* (-) infinity - (+) infinity
b* (-) infinity - (+) infinity
T/F
XYZ are chromaticity coordinates
False
T/F The goal of color management is for all devices to have the same color gamut
False
T/F Mobile operating systems do not support ICC profiles
+ a* represents ________
-a* represents_________
a*
+Red, -Green
b*
+ yellow, -blue
What are the variables that represent the standard observer
xbar, ybar, zbar
Name the three common color spaces spoken about in lecture
Prophoto RGB
Adobe 1998
sRGB
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^)
Which CIELab variable(s) would you use to evaluate the reproduction of tones?
L*
Spectral locus, planckian locus, line of purples
T/F a densitometer is not an adequate measurement tool for providing color information
An object that is blue will most likely be reflecting the most in what nanometer or nanometer range?
400nm or anything around there
L*= 0
a* = 0
b* = 0
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?)
When speaking about adequate editing conditions, why is middle gray recommended for walls and monitor backgrounds
The exact dimensions of the color checker were made to ____________?
fill/fit 35mm film
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)
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)
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
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)