In-house seminar on the how's and why's of color measurement for detergency evaluation March 3, 2011 Prepared by MdMo, SJsm, NBS and TDa Human color perception, physical phenomena and color coordinates Instruments for color measurement (in Nz) and associated software Processing of data from the various instruments – comparisons between the instruments based on real-life sample data The special problem of UV light and optical brighteners – some real-life sample data Whiteness measurements/calculations (advanced topic – postponed)
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In-house seminar on the how's and why's of color measurement for detergency evaluation
March 3, 2011Prepared by MdMo, SJsm, NBS and TDa
Human color perception, physical phenomena and color coordinates
Instruments for color measurement (in Nz) and associated software
Processing of data from the various instruments – comparisons between the instruments based on real-life sample data
The special problem of UV light and optical brighteners – some real-life sample data
UV light (UV = ultraviolet) UV-lys light with a wavelength between 50 and 400 nm (approx)
UV filter UV-filter
value ? lightness, L*
vividness ? see saturation, b*
whiteness hvidhed
Measurable quantities (in principle)
irradiance irradians radiant power per area received at an illuminated surface
radiant energy strålingsenergi
radiant power strålingseffekt radiant energy per time
radiance factor
reflectance, spectral reflectance reflektans ratio of reflected radiant power to incident radiant power
at a certain wavelength
diffuse reflectance
remission remission 'remittance' or the like would have been more consistent terminology
spectral irradiance spektral irradians radiant power, received at a surface, per area and per wavelength interval as a function of wavelength
spectral radiance spektral radians radiant power in the direction of the point from which the source is being observed, per area and per wavelength interval as a function of wavelength
spectral excitance (not exitance) spektral excitans (ikke exitans) total emitted radiant power per area of the radiation source
transmittance transmittans
Measurement process &equipment
aperture (måle)åbning
10/04/2023 NOVOZYMES PRESENTATION 3
Human color perception, physical phenomena and color coordinates
X
Y
Z
R
G
B
x
y
z
L
a
b
L*
a*
b*
r
g
b
10/04/2023 NOVOZYMES PRESENTATION 4
OBJECT
LIGHT SOURCE
OBSERVER / DETECTOR
Observing situation
10/04/2023 NOVOZYMES PRESENTATION 5
Daylight Tungsten Fluorescent
400 500 600 700
Wavelength [nm]
E l D65
400 500 600 700
Wavelength [nm]
E l A
400 500 600 700
Wavelength [nm]
F2E l
LightSource
Illuminant
Light source and illuminant
10/04/2023 NOVOZYMES PRESENTATION 6
Daylight
400 500 600 700
Wavelength [nm]
E l D65
D65 simulates noon daylight in Western/Northern Europe.
Explanation for the D65 nomenclature:
D65: 6500 K (~6503.6 K) = corrected color temperature.
Reduction to one number – quantifying color difference in 3D
ΔE* = (ΔL*2+ Δa*2 + Δb*2)1/2
10/04/2023 NOVOZYMES PRESENTATION 21
Human color perception, physical phenomena and color coordinates
X
Y
Z
R
G
B
x
y
z
L
a
b
L*
a*
b*
r
g
b
10/04/2023 NOVOZYMES PRESENTATION 23
Color Eye 7000
Color Eye 7000
• Pulsed xenon light source• Measuring geometry d/8• Two spectral analyzers• Spectral range 360 nm to 750 nm (??)• Reflection registered at every 10 nm (??)• Calibration (according to message from Largo in 1996):
– 6 ceramic tiles calibrated by Macbeth in the US against a tile set traceable to NIST (National Institute of Standards and Technology)
– Tolerances 0.3 ΔE CMC 1:1 (white, medium gray, gray) and 0.5 ΔE CMC 1:1 (yellow, green, cyan)
– Daily calibration on black and white standards, control with green tile
MCS 521 VIS diode-array spectrophotometers from Zeiss (340-1000 nm)
Tidas 1
CLX 75 W xenon lamp
measuring unit OFR 90 with integrating sphere
Tidas 2
measuring unit OMK 500-H (380-900 nm)
with SVS CLH 500 halogen lamp (360-2400 nm)- measuring geometry 0/45 (15 individual optical fibersin 15×24 arrangement, double beam to spectrophotometer)- this measuring unit is recommended for textured samples
[Taken from Zeiss MCS 500 spectrophotometer brochure]
Konica-Minolta spectrophotometer CM-3610d
10/04/2023 NOVOZYMES PRESENTATION 29
Konica-Minolta spectrophotometer CM-3610d
• 4 pulsed xenon lamps• Numerical gloss control for excluding/including specular
component• Numerical UV control with filter cut-off at 400 nm or 420 nm• Dual channel sensor (photodiode arrays) arrangement • Spectral range 360 nm to 740 nm (??)• Reflection registered at every 10 nm (??)• Measuring geometry d/8
Number of colors that the image will be able to show (RGB16 enables 281,474,976,710,656 colors – because 216 x 216 x 216 = 281*1012 )
Sharpness function compensates for loss insharpness during ”scanning and printing”
Red\Green\Blue
10/04/2023 NOVOZYMES PRESENTATION 33
Using our ”Color Analyzer” software for the scanner, the image data is reduced to coordinates in the rgb-space. This is then further reduced into ”intensity”, which is
Black = (0, 0, 0)White = (1, 1, 1) or (255, 255, 255)
Red = (1, 0, 0) or (255, 0, 0)Green = (0, 1, 0) or (0, 255, 0)Blue = (0, 0, 1) or (0, 0, 255)