Psychophysics
The human vision is most precise when making …
Side-by-side comparisons
Name the Maxwell Triangle
Yellow, red, magenta, blue, cyan, green
What represents tristimulus values? What represents the chromaticity coordinates?
Tristimulus values → XYZ ; chromaticity coordinates → xyz
What are the three main color spaces?
ProPhoto RGB, Adobe 1998, sRGB
What is the definition of a preset?
Set of saved instructions that can be applied to to an image or set of images in a single step
Who discovered the concept of psychophysics?
Gustav-Theodor Fechner
Red + green = ? ; blue + green = ?
Yellow, cyan
What are the first four patches of the MacBeth ColorChecker?
Dark skin, light skin, blue sky, green foliage
What does the ICC stand for?
International Color Consortium
Dots ______ in density and the dyes used are ________ in continuous tone printing
Vary ; transparent
Name at least two examples of objective measurements.
Gamuts, gammas, total density range, signal to noise ratio
Name the three filter classifications
Selective by wavelength, non-selective by wavelength, selective by angle of polarization
What is the Munsell notation written symbolically? How about neutral colors?
H V/C ; N V/
What are the four rendering intents?
Perceptual, Saturation, ICC absolute colorimetric, media relative colorimetric
True or False, with halftone printing, halftone dots can’t be placed on top of each other
True
Name at least two examples of subjective measurements.
Sharpening artifacts, noise reduction artifacts, tone mapping, etc
Your original exposure is ISO 400, SS 1/60th, f/8. You use a filter with a factor of 4. By only changing shutter speed, what is the new exposure?
Filter factor → 2 stops lost
ISO 400, SS 1/15th, f/8
What are the names of the four sections on the ColorChecker (list them in order)?
Patches 1-4 : Memory Colors
Patches 5-12: Hard to Reproduce Colors
Patches 13-18: Gamut Colors
Patches 19-24: Neutral Colors
Describe gamut clipping and gamut compression.
Gamut clipping: out of gamut colors are mapped to the edge of the available gamut; make image more vibrant but cause loss of detail
Gamut compression: Available gamut is compressed so that out of gamut colors can be mapped; may cause lack of detail in saturated areas
What happens when the dithering path is altered?
The color appearance is changed
What is the definition of psychophysics?
A quantitative study of the relationship between physical stimuli and the sensations and perceptions of the effect
What is the range and peaks of the S, M, and L cones?
S → Blue, 400-500nm, 440nm; M → Green, 450-630nm, 544nm; Red → 500-700nm, 580nm
Label the chromaticity diagram.
A = spectral locus ; B = white point ; C = color gamut ; D = planckian locus ; E = sample ; F = line of purples
Name five ways you should prepare your environment when retouching an image.
Indirect lighting
Hood on your display
No windows
Gray room
Computer background as gray to avoid simultaneous contrast
Name a difference between AM screening and FM screening method. What do AM and FM stand for?
AM screening uses fixed dot spacing and variable dot size, FM screening uses variable dot spacing and variable dot size
Amplitude modulation, frequency modulation