ASTM E2152-01(2006)
(Practice)Standard Practice for Computing the Colors of Fluorescent Objects from Bispectral Photometric Data
Standard Practice for Computing the Colors of Fluorescent Objects from Bispectral Photometric Data
SIGNIFICANCE AND USE
The bispectral or two-monochromator method is the definitive method for the determination of the general radiation-transfer properties of fluorescent specimens (4). In this method, the measuring instrument is equipped with two separate monochromators. The first, the irradiation monochromator, irradiates the specimen with monochromatic light. The second, the viewing monochromator, analyzes the radiation leaving the specimen. A two-dimensional array of bispectral photometric values is obtained by setting the irradiation monochromator at a series of fixed wavelengths (μ) in the ultraviolet and visible range, and for each μ, using the viewing monochromator to record readings for each wavelength (λ) in the visible range. The resulting array, once properly corrected, is known as the Donaldson matrix, and the value of each element (μ,λ) of this array is here described as the Donaldson radiance factor (D(μ,λ)). The Donaldson radiance factor is an instrument- and illuminant-independent photometric property of the specimen, and can be used to calculate its color for any desired illuminant and observer. The advantage of this method is that it provides a comprehensive characterization of the specimen’radiation-transfer properties, without the inaccuracies associated with source simulation and various methods of approximation.
SCOPE
1.1 This practice provides the values and practical computation procedures needed to obtain tristimulus values, designated X, Y, Z and X10, Y10, Z10 for the CIE 1931 and 1964 observers, respectively, from bispectral photometric data for the specimen. Procedures for obtaining such bispectral photometric data are contained in Practice E 2153.
1.2 Procedures for conversion of results to color spaces that are part of the CIE system, such as CIELAB and CIELUV are contained in Practice E 308.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:E2152–01(Reapproved2006)
Standard Practice for
Computing the Colors of Fluorescent Objects from
Bispectral Photometric Data
This standard is issued under the fixed designation E2152; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The fundamental procedure for evaluating the color of a fluorescent specimen is to obtain bispectral
photometric data for specified irradiating and viewing geometries, and from these data to compute
tristimulus values based on a CIE (International Commission on Illumination) standard observer and
a CIE standard illuminant. Procedures for such computation are contained in this practice. This
practice also contains procedures for computing illuminant-specific spectral radiance factor values
from illuminant-independent bispectral photometric data.
1. Scope 2.2 CIE Standards:
CIE Publication 15.2, Colorimetry
1.1 This practice provides the values and practical compu-
tation procedures needed to obtain tristimulus values, desig-
nated X, Y, Z and X ,Y ,Z for the CIE 1931 and 1964
10 10 10
2.3 ISO Standards:
observers, respectively, from bispectral photometric data for
ISO 11476 Paper and Board—Determination of CIE-
the specimen. Procedures for obtaining such bispectral photo-
Whiteness, C/2 Degrees
metric data are contained in Practice E2153.
1.2 Procedures for conversion of results to color spaces that
3. Terminology
are part of the CIE system, such as CIELAB and CIELUV are
3.1 Definitions—The definitions contained in Terminology
contained in Practice E308.
E284 are applicable to this practice.
1.3 This standard may involve hazardous materials, opera-
3.2 Definitions of Terms Specific to This Standard:
tions, and equipment. This standard does not purport to
3.2.1 bispectrometer, n—an optical instrument equipped
address all of the safety concerns, if any, associated with its
with a source of irradiation, two monochromators, and a
use. It is the responsibility of the user of this standard to
detection system, such that a specimen can be measured at
establish appropriate safety and health practices and deter-
independently-controlled irradiation and viewing wavelengths.
mine the applicability of regulatory limitations prior to use.
The bispectrometer is designed to allow for calibration to
2. Referenced Documents provide quantitative determination of the bispectral radiation-
transfer properties of the specimen.(5)
2.1 ASTM Standards:
E284 Terminology of Appearance
NOTE 1—Typically, a reference detection system monitors the radiation
E308 Practice for Computing the Colors of Objects by incident on the specimen. This reference detection system serves to
compensate for both temporal and spectral variations in the flux incident
Using the CIE System
upon the specimen, by normalization of readings from the instrument’s
E2153 Practice for Obtaining Bispectral Photometric Data
emission detection system.
for Evaluation of Fluorescent Color
3.2.2 diagonal elements, n—elements of a bispectral matrix
for which irradiation and viewing wavelengths are equal.
3.2.3 fluorescence, n—this standard uses the term “fluores-
This practice is under the jurisdiction of ASTM Committee E12 on Color and
cence” as a general term, including both true fluorescence
Appearance and is the direct responsibility of Subcommittee E12.05 on Fluores-
cence.
Current edition approved Dec. 1, 2006. Published December 2006. Originally
approved in 2001. Last previous edition approved in 2001 as E2152 - 01. DOI:
10.1520/E2152-01R06. AvailablefromU.S.NationalCommitteeoftheCIE(InternationalCommission
For referenced ASTM standards, visit the ASTM website, www.astm.org, or on Illumination), C/o Thomas M. Lemons, TLA-Lighting Consultants, Inc., 7 Pond
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM St., Salem, MA 01970, http://www.cie-usnc.org.
Standards volume information, refer to the standard’s Document Summary page on Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E2152–01 (2006)
-8
(with a luminescent decay time of less than 10 s) and 6.2.1 When object will be viewed indoors, by daylight
phosphorescence with a delay time short enough to be indis- filtered through a glass window, use values for the extended
tinguishable from fluorescence for the purpose of colorimetry. version of Illuminant C defined in ISO 11476.
3.2.4 off-diagonal element, n—any element of a bispectral 6.2.2 When object will be viewed outdoors, by unfiltered
matrix for which irradiation and viewing wavelengths are not daylight, use values for CIE Illuminant D65, or other daylight
equal. illuminants, as defined by the formulas developed by Judd, and
presented in CIE 15.2.
4. Summary of Practice
6.2.3 When object will be viewed under well-defined spe-
4.1 Procedures—Procedures are given for computing from cial conditions of irradiation which are not similar to any
bispectral photometric measurements the CIE tristimulus val-
standard illuminant, a provisional illuminant may be defined.
ues X, Y, Z for the CIE 1931 standard observer and the CIE Such a provisional illuminant must represent the relative
1964 supplementary standard observer. While recognizing the
spectral irradiance upon the object surface under these special
CIErecommendationofnumericalintegrationat1nmintervals conditions.
(in Publication 15.2) as the basic definition, this practice is
limited in scope to measurements and calculations using 7. Calculation
spectral intervals greater than or equal to 5 nm.
7.1 Calculation of Colorimetric Quantities—Use the
4.2 Calculations—CIE tristimulus values X, Y, Z or X ,
10 method of calculating tristimulus values at 5 nm intervals over
Y ,Z are calculated by numerical summation of the prod-
10 10 the viewing wavelength range 380 to 780 nm, and irradiation
uctsofweightingfactorsforselectedilluminantsandobservers
wavelength range 300 to 780 nm.
with the bispectral Donaldson radiance factor of the specimen.
7.2 Calculation of Tristimulus Values—The calculation pro-
The tristimulus values so calculated may be converted to
cedures described below involve numerical summation of the
coordinates in a more nearly uniform color space such as
products of the Donaldson radiance factor of the specimen and
CIELAB or CIELUV.
a bispectral factor derived from the tabulated standard illumi-
nant and observer functions.After normalization, the sums are
5. Significance and Use
the CIE tristimulus values X, Y, Z. (3, 4, 5)
5.1 The bispectral or two-monochromator method is the
7.2.1 Application of Illuminant Weights—Select the desired
definitive method for the determination of the general
CIE standard illuminant from Tables given in Practice E308.
radiation-transfer properties of fluorescent specimens (4).In
Multiply each element D(µ,l) of the specimen’s Donaldson
this method, the measuring instrument is equipped with two
matrix by the tabulated value of the relative spectral power of
separate monochromators. The first, the irradiation monochro-
the illuminant F at the element’s irradiation wavelength (µ).
mator, irradiates the specimen with monochromatic light. The
7.2.2 Calculation of Stimulus Function—Obtain the sum
second, the viewing monochromator, analyzes the radiation
over µ of these products at 5 nm intervals over the wavelength
leaving the specimen. A two-dimensional array of bispectral
range 300 to 780 nm. The sum obtained at each viewing
photometric values is obtained by setting the irradiation
wavelength l is the value of the specimen’s stimulus function
monochromator at a series of fixed wavelengths (µ) in the
(relative spectral radiance) F(l), under the specified conditions
ultraviolet and visible range, and for each µ, using the viewing
of irradiation. From these values, either tristimulus values or
monochromator to record readings for each wavelength (l) in
spectral radiance factor values may be derived.
the visible range. The resulting array, once properly corrected,
is known as the Donaldson matrix, and the value of each
F~l! 5 F~µ!D~µ,l! (1)
(
µ 5 300
element (µ,l) of this array is here described as the Donaldson
radiance factor (D(µ,l)). The Donaldson radiance factor is an 7.2.3 Derivation of Tristimulus Values—Use the color-
matching functions selected in 6.1. Multiply the specimen’s
instrument- and illuminant-independent photometric property
of the specimen, and can be used to calculate its color for any stimulus function at each viewing wavelength (l) by the
corresponding tabulated values of the observer color-matching
desired illuminant and observer. The advantage of this method
functions. Obtain the sum of these spectral products at 5 nm
is that it provides a comprehensive characterization of the
intervals over the wavelength range 380 to 780 nm:
specimen’s radiation-transfer properties, without the inaccura-
cies associated with source simulation and various methods of
–
X 5 k x~l!F~l! (2)
approximation. (
l5 380
6. Procedure
–
Y 5 k y~l!F~l!
(
l5 380
6.1 Selecting Standard Observer—Select standard observer
according to the guidelines of Practice E308.
–
Z 5 k z l!F l!
~ ~
(
6.2 Selecting Illuminants—Select illuminants that are simi-
l5 380
lar to the light under which the objects will be viewed or for
where:
which their colors will be specified or evaluated. In general,
k = the normalization constant:
follow the recommendations of Practice E308. For fluorescent
samples, however, special attention must be given to the
k 5 (3)
relative UV content of the selected illuminants and the light
–
F~l!y~l!
(
under which the objects will be viewed. l5 380
E2152–01 (2006)
7.3 Derivation of Other Colorimetric Quantities—Other 7.6.2 Viewing Wavelength Range Less Than 380-780 nm—
col
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