ASTM E1336-96(2003)
(Test Method)Standard Test Method for Obtaining Colorimetric Data From a Visual Display Unit by Spectroradiometry
Standard Test Method for Obtaining Colorimetric Data From a Visual Display Unit by Spectroradiometry
SIGNIFICANCE AND USE
The most fundamental method for obtaining CIE tristimulus values or other color coordinates for describing the colors of visual display units (VDUs) is by the use of spectroradiometric data. (See CIE No. 18 and 63.) These data are used by summation together with numerical values representing the 1931 CIE Standard Observer and normalized to Km, the maximum spectral luminous efficacy function.
The special requirements for characterizing VDUs possessing narrow or discontinuous spectra are presented and discussed. Modifications to the requirements of Practice E 308 are given to correct for the unusual nature of narrow or discontinuous sources.
SCOPE
1.1 This test method prescribes the instrumental measurements required for characterizing the color and brightness of VDUs.
1.2 This test method is specific in scope rather than general as to type of instrument and object.
1.3 The values stated in SI units are to be regarded as the standard.
1.4 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:E1336–96(Reapproved2003)
Standard Test Method for
Obtaining Colorimetric Data From a Visual Display Unit by
Spectroradiometry
This standard is issued under the fixed designation E1336; 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 characterizing the color and luminance of a visual display unit
(VDU) is to obtain the spectroradiometric data under specified measurement conditions, and from
these data to compute CIE chromaticity coordinates and absolute luminance values based on the 1931
CIE Standard Observer.The considerations involved and the procedures to be used to obtain precision
colorimetric data for this purpose are contained in this test method. The values and procedures for
computing CIE chromaticity coordinates are contained in Practice E308.The procedures for obtaining
spectroradiometric data are contained in Test Method E1341. This test method includes some
modifications to the procedures given in Practice E308 that are necessary for computing the absolute
luminance values ofVDUs.This procedure is intended to be generally applicable to anyVDU device,
including but not limited to cathode ray tubes (CRT), liquid crystal displays (LCD), and electrolu-
minescent displays (ELD).
1. Scope E308 Practice for Computing the Colors of Objects by
Using the CIE System
1.1 This test method prescribes the instrumental measure-
E1341 Practice for Obtaining Spectroradiometric Data from
ments required for characterizing the color and brightness of
Radiant Sources for Colorimetry
VDUs.
2.2 CIE Publications:
1.2 This test method is specific in scope rather than general
Publication CIE No. 18 Principles of Light Measurements
as to type of instrument and object.
Publication CIE No. 15.2 Colorimetry, 2nd ed., 1986
1.3 The values stated in SI units are to be regarded as the
PublicationCIENo.63 SpectroradiometricMeasurementof
standard.
Light Sources, 1984
1.4 This standard does not purport to address all of the
2.3 IEC Publications:
safety concerns, if any, associated with its use. It is the
Publication No. 441 Photometric and Colorimetric Methods
responsibility of the user of this standard to establish appro-
of Measurement of the Light Emitted by a Cathode-Ray
priate safety and health practices and determine the applica-
Tube Screen, 1974
bility of regulatory limitations prior to use.
3. Terminology
2. Referenced Documents
3.1 The definitions of appearance terms in Terminology
2.1 ASTM Standards:
E284 are applicable to this test method.
E284 Terminology of Appearance
4. Summary of Test Method
This test method is under the jurisdiction of ASTM Committee E12 on Color
4.1 Procedures are given for obtaining spectroradiometric
and Appearance and is the direct responsibility of Subcommittee E12.06 on Image
data and for the calculation of CIE tristimulus values and other
Based Color Measurement.
Current edition approved July 10, 2003. Published July 2003. Originally
approved in 1991. Last previous edition approved in 1996 as E1336 – 96. DOI:
10.1520/E1336-96R03. 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 from International Electrotechnical Commission (IEC), 3 rue de
Varembé, Case postale 131, CH-1211, Geneva 20, Switzerland, http://www.iec.ch.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E1336–96 (2003)
color coordinates to describe the colors of VDUs. Modifica- preferable to have more than one standard lamp to permit
tions to the standard calculation procedures of Practice E308 cross-checks and to allow calibration at a range of luminance
are described. levels.
7.2.2 Monochromatic emission sources such as a low-
pressure mercury arc lamp or tunable laser should also be
5. Significance and Use
available for use in calibrating the wavelength scale.
5.1 The most fundamental method for obtaining CIE tris-
7.2.3 The electrical supplies for the calibration sources
timulus values or other color coordinates for describing the
should be of the constant current type. The supply should be
colors of visual display units (VDUs) is by the use of
linear and not a switching supply. Current regulation should be
spectroradiometric data. (See CIE No. 18 and 63.) These data
maintained to better than 0.1 %. At this level the radiant flux
are used by summation together with numerical values repre-
from the calibration source is at least an order of magnitude
sentingthe1931CIEStandardObserverandnormalizedto K ,
m
more stable than the flux from a VDU.
the maximum spectral luminous efficacy function.
7.2.4 There should be a standard for length measurements
5.2 The special requirements for characterizing VDUs pos-
available (such as a high quality metric rule) since absolute
sessing narrow or discontinuous spectra are presented and
irradiance calibration must be performed at an exact distance
discussed. Modifications to the requirements of Practice E308
from the filament of the calibration lamp.
are given to correct for the unusual nature of narrow or
7.3 Receiving Optics—To maximize the light throughput
discontinuous sources.
the number of optical surfaces between the source of light
should be kept to a minimum. In extended diffuse sources
6. Requirements When Using Spectroradiometry
(such asVDUs) only a set of limiting apertures will be needed.
6.1 When describing the measurement of VDUs by spectro-
In some instances, it may be desirable to image the VDU with
radiometry, the following must be specified:
an intermediate focusing lens or mirror assembly. Care should
6.1.1 The radiometric quantity determined, such as the
be taken to use a magnification that will adequately fill the
2 2
irradiance (W/m ) or radiance (W/m -sr), or the photometric
entrance slit when viewing both the calibration and test source.
quantitydetermined,suchasilluminance(lm/m )orluminance
2 2
8. Calibration and Verification
(lm/m -sr or cd/m ). The use of older, less descriptive names
8.1 Calibration and its verification are essential steps in
or units such as phot, nit, stilb is not recommended.
ensuring that precise and accurate results are obtained by
6.1.2 The geometry of the measurement conditions, includ-
spectroradiometric measurements. They require the use of
ing, whether a diffuser was used and the material from which
physical standards, some of which may not be normally
it was constructed, the distances from the VDU, the size of the
supplied by commercial instrument manufacturers. It remains
area to be measured on the VDU, the uniformity of the VDU
the user’s responsibility to obtain and use the physical stan-
across the area to be measured, the microstructure of the VDU
dards necessary to keep his instrument in optimum working
picture elements, and the presence of any special intermediate
condition.
optical devices such as integrating spheres.
8.2 Radiometric Scale:
6.1.3 The spectral parameters, including the spectral region,
8.2.1 Zero Calibration or Its Verification—All photometric
wavelength measurement interval, and spectral bandwidth.
devices have some inherent photocurrent, even in the absence
These must be specified since the various VDU technologies
of light. This so called “dark current” must be measured and
may demand more or less stringent requirements.
subtracted from all subsequent readings either electrically or
6.1.4 The type of standard used to calibrate the system, a
computationally.
standard lamp, a calibrated source, or a calibrated detector, and
8.2.2 Radiometric Scale Calibration— A physical standard
the source of the calibration.
of spectral irradiance is normally used for calibration.After the
6.1.5 The physical and temporal characteristics of the VDU
dark current has been measured, the calibration source is
including, refresh or field rate, convergence and purity adjust-
positioned in front of the receiving optics at the specified
ments (if the manufacturer allows such), luminance level, and
distance and operated at the specified electric current. This
any spectral line character in the emission from the VDU. The
provides a good approximation to a Plankian radiator across
integration time of the detector system should be noted in
the visible spectrum. The calibration source is measured and
relation to the refresh or field rate of the VDU. (See IEC No.
the values of the dark-current-corrected photocurrent are re-
441.)
corded. These photocurrents are then related to the calibration
values of spectral irradiance that were provided by the stan-
7. Apparatus
dardizing laboratory. The ratio of spectral irr
...
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