Color Analysis Flashcards
Colorant
Any chemical that imparts color
Natural or synthetic
Pigment
Natural substance in plant or animal tissue that imparts color
Dyes
Any substances that lend color to material
Food grade water soluble colorant
Certified by FDA
Lakes
Oil dispersible colorants
Properties of materials
Gloss
Transparency
Haziness
Turbidity
Factors in color detection
Light source
Object
Observer or detector
Light may be
Reflected
Transmitted
Absorbed
Refracted
White color
All radiant NRG is reflected
Black color
Light is absorbed almost completely
Color
Sensation experienced when visible light falls upon retina
Cones
Responsible for daylight and color vision
Rods
Responsible for night vision
No color discrimination
Types of cones
Sensitive to red, green, blue
Short, medium, long wavelengths
Opponent color theory
Signals from receptors transformed to 1 brightness signal + 2 hue signals (red/green, yellow/blue)
Reflect
Light ray approaches a surface and bounces back
Transmit
Light ray hits and object and penetrates through the material
Absorb
Material soaks up light and absorbs it as energy
Refract
Light wave changes direction as it passes from one medium to another
USDA color standards ex
Honey
French fries
Peanut butter
Orange juice
Lovibond scale
Tintometer
Vegetable oils
Beer
Syrups
Lab color space
L = lightness (0-100)
a = red (+) or green (-)
b = yellow (+) or blue (-)
Colorimeter
Spectrophotometers that scans the visible spectrum
Evaluate how much of the wavelength was absorbed
Total color difference
dE indicates the magnitude of difference
Tolerance contours
Colors in ellipses are indistinguishable from the color at the center
Contour of the ellipse represents just noticeable differences
Spectrophotometer
Measures transmittance
More sensitive
More versatile
How colorimeters work
Light shines onto surface of sample
As light reflects back into device, it passes through 3 filters
Filters provide values that match how our eyes see color
