Fred W. Billmeyer, "Precision of Color Measurement with the GE Spectrophotometer. I. Routine Industrial Performance*," J. Opt. Soc. Am. 55, 707-716 (1965)
A round-robin study of color measurement on the General Electric recording spectrophotometer was carried out by 15 participating laboratories, using transparent glass filters and opaque plastic and glass specimens. In terms of CIE Y and x, y for Illuminant C (daylight), 95% confidence limits for individual measurements averaged ±1.5% for Y and ±0.0165 for x and y if all the data were included. Elimination of results known or suspected to contain systematic errors reduced these values to ±0.57% for Y and ±0.0119 for x and y. The confidence limits for x and y are much greater for low-luminance than for high-luminance specimens, but those for Y showed relatively little dependence on luminance. The short-time repeatability of the spectrophotometer averaged ±0.09% for Y and ±0.0007 for x and y, while its reproducibility over a 14-month period averaged ±0.62% for Y and ±0.0028 for x and y.
The results of this round-robin study clearly show, as in the repeatability and reproducibility studies, that the GE spectrophotometer, when suitably calibrated and operated, can still be considered the referee instrument for accurate color measurement. Serious doubt is cast, however, on the suitability of the procedures generally practiced for the calibration and operation of this instrument.
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1 instrument, 4 measurements in rapid succession without removing sample, automatic tristimulus integrator.
1 instrument, 4 measurements in rapid succession without removing sample, digital readout and computer integration.
1 instrument, 30–34 measurements over a 14-month period.
1 instrument, 11 measurements over a 7-month period.
Table V
Confidence limits for CIE coordinates for acrylic reflectance samples.
Four measurements were taken under conditions of Notes a and b of Table IV. Where two numbers are given in parentheses, the first represents measurements with the 100% cam; the second, with the 20% cam.
Table IX
Average, high, low, and median confidence limits.
CIE function
Samples
Data
Average
High
Low
Median
Y (%)
All
All
1.51
4.73
0.41
0.92
Selected
0.57
1.37
0.25
0.50
Note a
0.09
0.38
(0)
0.07
Note c
0.62
1.53
0.16
0.55
x, y
All
All
0.0165
0.1132
0.0007
0.0047
Selected
0.0119
0.1284
0.0006
0.0033
Note a
0.0009
0.0043
(0)
0.0006
Note c
0.0028
0.0184
0.0003
0.0010
x, y
High luminance
All
0.0022
0.0092
0.0007
0.0018
Selected
0.0018
0.0042
0.0006
0.0015
Note a
0.0005
0.0017
(0)
0.0004
Note c
0.0011
0.0033
0.0003
0.0009
x, y
Low luminance
All
0.0293
0.1132
0.0022
0.0170
Selected
0.0209
0.1284
0.0018
0.0100
Note a
0.0012
0.0043
0.0003
0.0008
Note c
0.0053
0.0184
0.0006
0.0015
Table X
Reports omitted in calculations designated “Selected data.”
1 instrument, 4 measurements in rapid succession without removing sample, automatic tristimulus integrator.
1 instrument, 4 measurements in rapid succession without removing sample, digital readout and computer integration.
1 instrument, 30–34 measurements over a 14-month period.
1 instrument, 11 measurements over a 7-month period.
Table V
Confidence limits for CIE coordinates for acrylic reflectance samples.
Four measurements were taken under conditions of Notes a and b of Table IV. Where two numbers are given in parentheses, the first represents measurements with the 100% cam; the second, with the 20% cam.
Table IX
Average, high, low, and median confidence limits.
CIE function
Samples
Data
Average
High
Low
Median
Y (%)
All
All
1.51
4.73
0.41
0.92
Selected
0.57
1.37
0.25
0.50
Note a
0.09
0.38
(0)
0.07
Note c
0.62
1.53
0.16
0.55
x, y
All
All
0.0165
0.1132
0.0007
0.0047
Selected
0.0119
0.1284
0.0006
0.0033
Note a
0.0009
0.0043
(0)
0.0006
Note c
0.0028
0.0184
0.0003
0.0010
x, y
High luminance
All
0.0022
0.0092
0.0007
0.0018
Selected
0.0018
0.0042
0.0006
0.0015
Note a
0.0005
0.0017
(0)
0.0004
Note c
0.0011
0.0033
0.0003
0.0009
x, y
Low luminance
All
0.0293
0.1132
0.0022
0.0170
Selected
0.0209
0.1284
0.0018
0.0100
Note a
0.0012
0.0043
0.0003
0.0008
Note c
0.0053
0.0184
0.0006
0.0015
Table X
Reports omitted in calculations designated “Selected data.”