ASTM E1336-96

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E 1336 – 96
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Obtaining Colorimetric Data From a Visual Display Unit by
Spectroradiometry
This standard is issued under the fixed designation E 1336; 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 (e) 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 Method E 308. The procedures for obtaining
spectroradiometric data are contained in Test Method E 1341. This test method includes some
modifications to the procedures given in Method E 308 that are necessary for computing the absolute
luminance values of VDUs. This procedure is intended to be generally applicable to any VDU device,
including but not limited to cathode ray tubes (CRT), liquid crystal displays (LCD), and electrolu-
minescent displays (ELD).
1. Scope Publication CIE No. 18 Principles of Light Measurements
Publication CIE No. 15.2 Colorimetry, 2nd ed., 1986
1.1 This test method prescribes the instrumental measure-
Publication CIE No. 63 Spectroradiometric Measurement of
ments required for characterizing the color and brightness of
Light Sources, 1984
VDUs.
2.3 IEC Publications:
1.2 This test method is specific in scope rather than general
Publication No. 441 Photometric and Colorimetric Methods
as to type of instrument and object.
of Measurement of the Light Emitted by a Cathode-Ray
1.3 The values stated in SI units are to be regarded as the
Tube Screen, 1974
standard.
1.4 This standard does not purport to address all of the
3. Terminology
safety concerns, if any, associated with its use. It is the
3.1 The definitions of appearance terms in Terminology
responsibility of the user of this standard to establish appro-
E 284 are applicable to this test method.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4. Summary of Test Method
2. Referenced Documents 4.1 Procedures are given for obtaining spectroradiometric
data and for the calculation of CIE tristimulus values and other
2.1 ASTM Standards:
color coordinates to describe the colors of VDUs. Modifica-
E 284 Terminology Relating to Appearance
tions to the standard calculation procedures of Practice E 308
E 308 Practice for Computing the Colors of Objects by
are described.
Using the CIE System
E 1341 Practice for Obtaining Spectroradiometric Data
5. Significance and Use
from Radiant Objects
5.1 The most fundamental method for obtaining CIE tris-
2.2 CIE Publications:
timulus 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
This test method is under the jurisdiction of ASTM Committee E-12 on
Appearance and is the direct responsibility of Subcommittee E12.06 on Appearance
of Displays. Currently available through the U.S. National Committee of the CIE, c/o Mr.
Current edition approved May 10, 1996. Published July 1996. Originally Thomas M. Lemons, TLA-Lighting Consultants, Inc., 7 Pond Street, Salem, MA
e1
published as E 1336 – 91. Last previous edition E 1336 – 91 . 01970-4819.
2 4
Annual Book of ASTM Standards, Vol 06.01. Available from International Electrotechnical Commission (IEC), P.O. Box
131, 1211 Geneva, 20 Switzerland. Electronic mail: dn@iec.ch.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E 1336
are used by summation together with numerical values repre- more stable than the flux from a VDU.
senting the 1931 CIE Standard Observer and normalized to K , 7.2.4 There should be a standard for length measurements
m
the maximum spectral luminous efficacy function. available (such as a high quality metric rule) since absolute
5.2 The special requirements for characterizing VDUs pos- irradiance calibration must be performed at an exact distance
sessing narrow or discontinuous spectra are presented and from the filament of the calibration lamp.
discussed. Modifications to the requirements of Practice E 308 7.3 Receiving Optics—To maximize the light throughput
are given to correct for the unusual nature of narrow or the number of optical surfaces between the source of light
discontinuous sources. should be kept to a minimum. In extended diffuse sources
(such as VDUs) only a set of limiting apertures will be needed.
6. Requirements When Using Spectroradiometry
In some instances, it may be desirable to image the VDU with
6.1 When describing the measurement of VDUs by spectro-
an intermediate focusing lens or mirror assembly. Care should
radiometry, the following must be specified:
be taken to use a magnification that will adequately fill the
6.1.1 The radiometric quantity determined, such as the
entrance slit when viewing both the calibration and test source.
2 2
irradiance (W/m ) or radiance (W/m -sr), or the photometric
2 8. Calibration and Verification
quantity determined, such as illuminance (lm/m ) or luminance
2 2
8.1 Calibration and its verification are essential steps in
(lm/m -sr or cd/m ). The use of older, less descriptive names or
ensuring that precise and accurate results are obtained by
units such as phot, nit, stilb is not recommended.
spectroradiometric measurements. They require the use of
6.1.2 The geometry of the measurement conditions, includ-
physical standards, some of which may not be normally
ing, whether a diffuser was used and the material from which
supplied by commercial instrument manufacturers. It remains
it was constructed, the distances from the VDU, the size of the
the user’s responsibility to obtain and use the physical stan-
area to be measured on the VDU, the uniformity of the VDU
dards necessary to keep his instrument in optimum working
across the area to be measured, the microstructure of the VDU
condition.
picture elements, and the presence of any special intermediate
8.2 Radiometric Scale:
optical devices such as integrating spheres.
8.2.1 Zero Calibration or Its Verification—All photometric
6.1.3 The spectral parameters, including the spectral region,
devices have some inherent photocurrent, even in the absence
wavelength measurement interval, and spectral bandwidth.
of light. This so called “dark current” must be measured and
These must be specified since the various VDU technologies
may demand more or less stringent requirements. subtracted from all subsequent readings either electrically or
computationally.
6.1.4 The type of standard used to calibrate the system, a
standard lamp, a calibrated source, or a calibrated detector, and 8.2.2 Radiometric Scale Calibration—A physical standard
of spectral irradiance is normally used for calibration. After the
the source of the calibration.
6.1.5 The physical and temporal characteristics of the VDU dark current has been measured, the calibration source is
positioned in front of the receiving optics at the specified
including, refresh or field rate, convergence and purity adjust-
distance and operated at the specified electric current. This
ments (if the manufacturer allows such), luminance level, and
provides a good approximation to a Plankian radiator across
any spectral line character in the emission from the VDU. The
the visible spectrum. The calibration source is measured and
integration time of the detector system should be noted in
the values of the dark-current-corrected photocurrent are re-
relation to the refresh or field rate of the VDU. (See IEC No.
corded. These photocurrents are then related to the calibration
441.)
values of spectral irradiance that were provided by the stan-
7. Apparatus
dardizing laboratory. The ratio of spectral irradiance to photo-
7.1 The basic instrument requirement is a spectroradiomet- current becomes the instrument calibration factor. All subse-
ric system designed for the measurement of spectral radiance quent measurements are multiplied by this ratio.
or irradiance of light sources. See Practice E 1341 for details 8.2.3 Linearity Verification—Periodically after the radio-
on each of the parts of a spectroradiometer and how to calibrate metric and zero scale readings are established, the linearity of
and use the instrument. the scale should be verified.
7.2 Calibration Sources: 8.2.4 All calibrations should be performed using the same
7.2.1 The standard calibrat
...