nist2000 wht bkgrd
TRANSCRIPT
Color and Appearance Attributes
Richard W. HaroldColor and Appearance Consulting LLC
NOTE: This presentation was originally presented in the year 2000 at the NIST Color Workshop as a Keynote Speaker
Presentation. It is only 7.2 MB in Length. Additional, vastly improved Recent Presentations are available, but all far exceed 10
MB in Length
APPEARANCE: A Visual Sensation
CHROMATIC ATTRIBUTESRelated to color-hue, saturation, purity
GEOMETRIC ATTRIBUTESSurface properties associated with
the distribution of light from the object, such as gloss or haze
Opaque Non-MetalINCIDENT
LIGHT
SPECULARREFLECTION
DIFFUSEREFLECTION
MetalINCIDENT
LIGHTSPECULAR
REFLECTION
DIFFUSEREFLECTION
Translucent MaterialINCIDENT
LIGHT
SPECULARREFLECTION
DIFFUSEREFLECTION
DIFFUSETRANSMISSION
Transparent MaterialINCIDENT
LIGHT
SPECULARREFLECTION
DIFFUSETRANSMISSION
REGULARTRANSMISSION
Visual Observing Situation
OBJECT
LIGHT SOURCE
HUMAN OBSERVER
300 nm 450 550 650 1000 nm
VISIBLE SPECTRUM INFRAREDULTRAVIOLET
Spectral Power Distribution
UVX-
RAYSGAMMA
RAYSCOSMIC
RAYSINFRA-
REDMICRO-WAVES
TV RADIOELECTRIC
POWER
.00001nm .001nm 1nm 10nm .01cm .1 m 10 m 100m 106m
DaylightRelativeEnergy
Light Sources CIE Illuminants
Common Illuminants
CIE X,Y,Z Tristimulus Values for Orange
X = 41.73Y = 33.77Z = 2.34
Non-Uniformity of CIE Color Space
x
y
OPPONENT COLORS THEORY
BRAIN
BLUE RECEPTORS
GREEN
RECEPTORS
RED RECEPTORS
BLUE-YELLOW SIGNAL
BLACK-WHITE
SIGNAL
RED-GREEN SIGNAL
+60
-20
+20-40-60
-60-40
-20
0
+20
+60
+40
BLUE
RED
GREEN
YELLOW
WHITE
BLACK
LIGHTNESS
L = 58.12a = + 30.41b = + 36.26
100
+40
Comparison of Color Formulas
Hunter L, a, b (1958) CIE 1976 L* a* b*
CIE 1976 L* C* h
Hunter L, a, b (1958) CIE 1976 L*a*b*
Comparison of Hunter L, a, b to CIELAB
L* = 64.79a* = +32.21b* = +83.43
L = 58.12a = +30.41b = +36.26
Rectangular L* a* b* Color DifferencesSAMPLE STANDARD
COLORDIFFERENCE
S
L* = 75.7a* = +4.1b* = +87.6
L* = 71.6a* = +6.9b* = +78.7
Total Color Difference in Rectangular Coordinates
Sample Color
Standard Color
Sample Color
Standard Color
Interpretation of Color Differences
Instrumental Limit
10
1.0
2.0
5.0
0.5
0.2
0.01
TypicalIndustrialTolerance
Range
ApproximateVisual Limit
CIELAB UNITS
TYPICAL RECTANGULAR-COORDINATE TOLERANCES
Clothing Manufacturer
COLOR
Reds/Oranges
Greens
Yellows/Tans
Blues
Problem of Rectangular ± ∆ L* a* b* Tolerances
±∆ b*
±∆ a*
Product Standard
Acceptable Match
Visually Unacceptable Match
Yellow
+b*
Blue-b*
Red+a*
Green-a*
L* White
L* Black
C*ab
hab
L* = 64.79a* = 32.21b* = 83.43
L* = 64.78C*ab = 89.43hab = 68.89º
Tolerance Improvementwith ± ∆L* ± ∆C* ± ∆H* Coordinates
± ∆ L*
± ∆ C*
± ∆ H*
Product Standard
Acceptable Match
∆ECMC Total Color Difference
l:c = lightness to chroma ratio
Product Standard
HS
CcS
lSL
∆E*94 Total Color Difference
SL = 1SC = 1 + 0.045 C*ab
SH = 1 + 0.015 C*ab
kL = kC = kH = 1 under reference conditions
HS
CS
SL
Product Standard
∆E*2000? Total Color Difference
SL = 1
SH = 1 + 0.015 C*Tf
RT=HSCS
SL
Product Standard
45°/ 0°
ASTM D1729 Standard Practice for Visual Evaluation
• LIGHT SOURCESo Daylight (D50 ,D65 or D75) - Specifyo Incandescent - 2856Ko Cool White Fluorescent - 4200K
• PHOTOMETRIC CONDITIONS o Illumination of 810-1880 Lux
• GEOMETRIC CONDITIONSo Lighting overhead (0°)o Viewing (45°)
• BACKGROUND and SURROUNDo Neutral Greyo Uncluttered
Visually Evaluating Appearance
GLOSSCOLOR
60° 60°
85°85°20°20°
ASTM D523 Glossmeter Geometries
Variations in Paint Finish – “Orange Peal”
DISTINCTNESS
OF IMAGESPECULAR
HAZE
DIFFUSE30° 30°
DOI Abridged Goniophotometer
0°/45° 45°/ 0°
CIE Reciprocal Geometries
1928 Hardy Recording Photoelectric Color Analyzer
High Gloss
Matte
Textured
HIGH-GLOSS
Light Distribution Varies with Surface Smoothness
MATTE
SEMI-GLOSS
Goniophotometric Data for 45º Incident Light
Comparison of Glossy Red Plastic Other Textures
Goniophotometric Data for 45º Incident Light
Comparison of Different Textures of Red Plastic
Goniophotometric Data for 45º Incident Light
Comparison of Different Textures of Red Plastic
Integrating Sphere
White or BlackSpecular Port
Cover
Detector
Baffle
Lamp
CIE d/0 Geometry
CIE 45/0 Geometry
The Ideal Sample for Color Measurement
• Totally Opaque or Transparent• Flat• Smooth• Uniform• No-directionality• Not-photochromic• Not-thermochromic• Not-hygrochromic
FluorescenceDaylight
Illumination
Ultra Violet Illumination
ChromaFlair® Interference Pigments
Top half 45º/0º – Bottom half 0º/10º
ASTM Illuminating/Viewing Angle Nomenclature
Illumination angle=45º, Viewing Angle=65º, Aspecular Angle=45+65=110º
Dynamic Color AreaPearlescent/Interference
Samples
100 a*
b*
Sources of Measurement Differences
• Instrumental – sphere (d/8°) or 0°/45° or ?• Specimen Preparation• Specimen Presentation
BCRA Standards Set
Small Area View BCRA Tile Holder
Use And Care of Instrument Standards
• Permanent reference base against which instrumental measurements are made
• Accuracy and precision of appearance measurements depend upon initial calibration and condition of the standards
• Should be handled with care, cleaned according to instructions, and stored in the box provided