IEC 62977-2-1:2021

IEC 62977-2-1 ®
Edition 1.0 2021-01
INTERNATIONAL
STANDARD
colour
inside
Electronic displays –
Part 2-1: Measurements of optical characteristics – Fundamental measurements

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IEC 62977-2-1 ®
Edition 1.0 2021-01
INTERNATIONAL
STANDARD
colour
inside
Electronic displays –
Part 2-1: Measurements of optical characteristics – Fundamental measurements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.120; 31.260 ISBN 978-2-8322-9225-9

– 2 – IEC 62977-2-1:2021 © IEC 2021
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
2 Normative references . 9
3 Terms, definitions and abbreviated terms . 10
3.1 Terms and definitions . 10
3.2 Abbreviated terms . 11
4 General . 11
4.1 Measured basic quantities . 11
4.2 Electrical driving of the display (depending on the nature of the display) . 11
4.3 Data acquisition timing and display driving . 12
4.3.1 Stationary measurements . 12
4.3.2 Properties of display under test . 12
5 Standard measuring conditions . 12
5.1 Standard measuring environmental conditions . 12
5.2 Standard measuring darkroom conditions . 12
5.3 Standard setup conditions . 12
5.3.1 General . 12
5.3.2 Adjustment of display . 12
5.3.3 Starting conditions of measurements . 13
5.3.4 Conditions of measuring equipment . 13
5.4 Location of measurement field . 15
5.5 Standard test patterns . 16
5.6 Viewing direction coordinate system . 16
6 Simple box optical measurement methods . 17
6.1 General . 17
6.2 Test patterns. 17
6.3 Luminance . 18
6.3.1 Purpose . 18
6.3.2 Measuring conditions . 18
6.3.3 Measuring method . 18
6.4 Darkroom contrast ratio . 19
6.4.1 Purpose . 19
6.4.2 Measuring conditions . 19
6.4.3 Measuring method . 19
6.5 Luminance uniformity . 20
6.5.1 Purpose . 20
6.5.2 Measuring conditions . 20
6.5.3 Measuring method . 20
6.6 Chromaticity . 21
6.6.1 Purpose . 21
6.6.2 Measuring conditions . 21
6.6.3 Measuring method . 22
6.7 White chromaticity and correlated colour temperature . 22
6.7.1 Purpose . 22
6.7.2 Measuring conditions . 22

6.7.3 Measuring method . 22
6.8 Chromaticity non-uniformity . 23
6.8.1 Purpose . 23
6.8.2 Measuring conditions . 23
6.8.3 Measuring method . 23
6.9 Chromaticity/colour gamut area. 24
6.9.1 Purpose . 24
6.9.2 Measuring conditions . 24
6.9.3 Measuring method . 25
6.9.4 Chromaticity/colour gamut area in CIE 1931 and CIE 1976 chromaticity
diagram . 27
6.10 Luminance and colour variation with viewing direction . 28
6.10.1 Purpose . 28
6.10.2 Measuring conditions . 28
6.10.3 Measuring method . 28
7 Display multi-colour optical measuring methods . 30
7.1 General . 30
7.2 Test patterns. 30
7.3 Luminance . 33
7.3.1 Purpose . 33
7.3.2 Measuring conditions . 33
7.3.3 Measuring method . 34
7.4 Darkroom contrast ratio . 35
7.4.1 Purpose . 35
7.4.2 Measuring conditions . 35
7.4.3 Measuring method . 35
7.5 Luminance uniformity . 35
7.6 Chromaticity, tristimulus values, and spectra . 35
7.6.1 Purpose . 35
7.6.2 Measuring conditions . 36
7.6.3 Measuring method . 36
7.7 White chromaticity and correlated colour temperature . 36
7.7.1 Purpose . 36
7.7.2 Measuring conditions . 36
7.7.3 Measuring method . 36
7.8 Chromaticity/colour gamut area. 37
7.8.1 Purpose . 37
7.8.2 Measuring conditions . 37
7.8.3 Measuring method . 37
7.8.4 Chromaticity/colour gamut area in CIE 1931 and CIE 1976 chromaticity
diagram . 37
7.9 Chromaticity non-uniformity . 38
7.10 Luminance and colour variation with viewing direction . 38
7.10.1 Purpose . 38
7.10.2 Measuring conditions . 38
7.10.3 Measuring method . 38
8 CIELAB colour gamut volume . 39
8.1 Purpose . 39
8.2 Measuring conditions . 40

– 4 – IEC 62977-2-1:2021 © IEC 2021
8.3 Measuring method . 40
Annex A (normative) RGB boundary colours for CIELAB colour gamut volume
measurements . 43
A.1 General . 43
A.2 Equally-spaced 98 boundary colours on the RGB cube . 43
A.3 Recommended 602 boundary colours on the RGB cube . 46
Annex B (informative) Calculation method for CIELAB gamut volume. 61
B.1 Purpose . 61
B.2 Procedure for calculating the colour gamut volume . 61
B.3 Number of sampled colours . 62
B.4 RGB cube surface subdivision method for CIELAB colour gamut volume
calculation . 62
B.4.1 General . 62
B.4.2 Assumption . 62
B.4.3 Uniform RGB grid algorithm . 62
B.4.4 Software example execution . 65
Annex C (informative) Significance of Clause 6 . 74
C.1 Summary . 74
C.2 Significance of Clause 6 during the research and development stage . 74
C.3 Significance of Clause 6 during the manufacturing stage . 75
C.4 Significance of Clause 6 during the evaluation of other test results . 76
Annex D (informative) Colour-signal luminance . 77
Annex E (informative) Gamut rings . 78
E.1 General . 78
E.2 Visualization method . 79
E.3 Software example . 80
Bibliography . 82

Figure 1 – Layout diagram of measurement setup with terminology. 14
Figure 2 – Example of measurement locations with nine measurement locations
equally spaced in the display active area . 16
Figure 3 – Representation of the viewing direction, or direction of measurement . 17
Figure 4 – Example of centre box test patterns using the standard 4 % and 10 % area

boxes . 18
Figure 5 – Example of uniformity measurement locations with nine measurement
locations . 20
Figure 6 – Examples of a display with colour boundaries represented by the black
triangle in two common chromaticity diagrams . 26
Figure 7 – Top view example of configurations for measuring luminance and colour in

the horizontal viewing direction . 29
Figure 8 – Side view example of configurations for measuring luminance and colour in
the vertical viewing direction . 30
Figure 9 – Standard medium APL loading version of the colour tile test pattern with red,
green, blue, and white boxes used for luminance and colour measurements . 31
Figure 10 – Medium APL loading version of colour tile patterns illustrating the

sequence of test patterns used for luminance and colour measurements . 31
Figure 11 – Standard medium APL RGBCMY test pattern used for centre luminance
and colour measurements with 25 % APL . 33

Figure 12 – Sequence for measuring luminance at the nine display locations for all
coloured tile patterns . 34
Figure 13 – Example of range in colours produced by a given display as represented

by the CIELAB colour space . 42
Figure B.1 – Analysis flow chart for calculating the CIELAB gamut volume . 61
Figure B.2 – Example of tessellation using a 5 x 5 grid of surface colours on the
RGB cube . 64
Figure B.3 – Example of tessellation for the RGB cube using a 3 x 3 grid . 66
Figure B.4 – Example of tessellation for the CIELAB gamut volume using a 3 x 3 grid . 66
Figure C.1 – Example of conceptual scheme for the supply chain of displays and the
usage of the measurement methods (MM) of Clause 0 and Clause 0 . 74
Figure C.2 – Conceptual example of the evaluation of the components . 75
Figure C.3 – Example of a mechanical stress test . 76
Figure E.1 – Example of transformation of the CIELAB gamut volume (top) illustrated
by L* slices into the concentric areas of the gamut ring representation (bottom) . 79
Figure E.2 – Example of calculation of gamut rings using the data from Table B.1 . 80

Table 1 – Summary of display characteristics . 8
Table 2 – Example of luminance of white, red, green, and blue measured at nine
screen locations and the resulting average luminance . 21
Table 3 – Example of a white colour measured at nine screen locations and the
resulting chromaticity non-uniformity . 24
Table 4 – Standard digital-equivalent input signals for rendering the white, primary and
secondary colours in test patterns . 25
Table 5 – Example of report format for CIELAB gamut volume . 42
Table A.1 – Equally-spaced 98 RGB boundary colours used for CIELAB colour gamut
volume measurements . 44
Table A.2 – Recommended RGB boundary colours used for CIELAB colour gamut
volume measurements . 46
Table B.1 – Example data format used for CIELAB colour gamut volume
measurements . 65

– 6 – IEC 62977-2-1:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRONIC DISPLAYS –
Part 2-1: Measurements of optical characteristics –
Fundamental measurements
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62977-2-1 has been prepared by IEC technical committee 110:
Electronic displays.
The text of this International Standard is based on the following documents:
FDIS Report on voting
110/1256/FDIS 110/1275/RVD
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 62977 series, published under the general title Electronic displays,
can be found on the IEC website.

The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 8 – IEC 62977-2-1:2021 © IEC 2021
INTRODUCTION
This document describes the common optical measurement methods applicable in the field of
electronic display devices, which can overlap with some of the parts of existing documents
developed within TC 110 (IEC 61747-30-1 [1] , IEC 62341-6-1, IEC 61988-2-1 [2],
IEC 62715-5-1 [3]), that describe the optical measurement methods of the individual
technologies, such as LCD, OLED, PDP and others. This document on common optical
measurement methods is intended to be used as the reference document in future documents
and in revisions of existing documents (e.g. IEC 61747-30-1, IEC 62341-6-1, IEC 61988-2-1,
IEC 62715-5-1). The existing documents will be revised in their maintenance time to refer to
this document to the largest extent possible.
All documents in IEC TC 110 that are concerned with the measurement of optical properties of
electronic displays refer to a set of methods and procedures that are similar to each other, or
sometimes even identical. This document is intended to identify these methods and to describe
them, together with suitable precautions and diagnostics, as a reference for forthcoming
documents to make the work of the involved experts more efficient and to avoid duplication of
efforts.
Introduction of the common optical measurement method (COMM) is also related to a structure
where each kind of optical measurement finds its unambiguous position for identification of
similarities to other methods or for clarification of distinctions. This structural classification
together with a general taxonomy is supposed to make the process of document production
easier, faster and thus more effective.
The above characteristics are summarized in Table 1. The display characteristics that are
addressed in this part of IEC 62977 are indicated by a check mark √ in the table.
Table 1 – Summary of display characteristics
Location Direction Test pattern,
Illumination Temperature,
Variables Time electrical driving,
conditions humidity
(x, y)
(θ, φ) input signal
Data
sampling Fast Slow Slow √ Slow Slow √
condition
Evaluation
Results transitions temporal uniformity √ uniformity, √ static pattern, √ darkroom, √ standard
from one stability environment √
characteristic
indoor,
optical state (uniformity)
function (electro-
to another
optic transfer
outdoor
state
function, EOTF)
characteristic values
(e.g. threshold,
saturation)
Evaluation turn-on, luminance, √
1st order turn-off,
contrast, √
delay
chromaticity, √
(latency)
threshold, saturation
time periods,
values, steepness of
temporal
transitions, etc.
modulations
Evaluation flicker EOTF from which
2nd order prediction, the exponent gamma
moving is evaluated
picture
chromaticity/ colour
response
gamut area, √
time, etc.
colour gamut
volume, √
___________
Numbers in square brackets refer to the Bibliography.

ELECTRONIC DISPLAYS –
Part 2-1: Measurements of optical characteristics –
Fundamental measurements
1 Scope
This part of IEC 62977 specifies standard measurement conditions and measuring methods for
determining the optical characteristics of electronic display modules and systems. These
methods apply to emissive and transmissive direct view displays that render real 2D images on
a flat panel. This document evaluates the optical characteristics of these displays under
darkroom conditions. This document applies to the testing of display performance in response
to standard analogue or digital input signals that are not absolute luminance encoded. The input
signal is relative RGB without metadata information that codes for real luminance, colour space
or colour coordinates. These methods are limited to input signals with typical OETFs such as
defined in IEC 61966-2-1, ITU BT. Rec. 601, ITU BT. Rec.709, and ITU BT. Rec.2020. The tests
in this document are not approved for use with HDR input signals.
NOTE A flat panel or flat panel display is a display with a flat surface and minimal depth that emits visible light from
the surface. The display is subdivided into an array of electronically driven pixels which can be light valves modulating
a backlight, or self-luminous. Emissive/transmissive/reflective hybrid displays can be flat panel or flat panel displays.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60050-845, International Electrotechnical Vocabulary – Part 845: Lighting (available at
www.electropedia.org)
IEC 61966-2-1, Multimedia systems and equipment – Colour measurement and management –
Part 2-1: Colour management – Default RGB colour space – sRGB
IEC 62341-6-1, Organic light emitting diode (OLED) displays – Part 6-1: Measuring methods of
optical and electro-optical parameters
IEC TR 62977-2-3, Electronic display devices – Part 2-3: Measurements of optical properties –
Multi-colour test patterns
ISO 9241-305, Ergonomics of human-system interaction – Part 305: Optical laboratory test
methods for electronic visual displays
ISO 15076-1:2010, Image technology colour management – Architecture, profile format and
data structure – Part 1: Based on ICC.1:2010
ISO/CIE 11664-1, Colorimetry – Part 1: CIE standard colorimetric observers
ISO/CIE 11664-4, Colorimetry – Part 4: CIE 1976 L*a*b* colour space
rd
CIE 15:2004, Colorimetry, 3 edition

– 10 – IEC 62977-2-1:2021 © IEC 2021
CIE 168:2005, Criteria for the evaluation of extended-gamut colour encodings
CIE 233:2019, Calibration, characterization and use or array spectroradiometers
ITU-R BT.601, Studio encoding parameters of digital television for standard 4:3 and wide
screen 16:9 aspect ratios
ITU-R BT.709, Parameters values for the HDTV standards for production and international
programme exchange
ITU-R BT.2020, Parameters values for ultra-high definition television systems for production
and international programme exchange
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-845 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
signal pixel
smallest encoded picture element in the input image
Note 1 to entry: Signal pixel is defined as the unit of signal resolution.
3.1.2
pre-gamma average picture level
average input level of all signal pixels relative to an equivalent white pixel driven by a digital
RGB input
Note 1 to entry: Unless otherwise stated, the pre-gamma average picture level (APL) will simply be referred to as
average picture level in this document.
Note 2 to entry: The APL will normally be expressed as a percentage, where a full white screen at maximum drive
level would be 100 % APL.
Note 3 to entry: The pre-gamma APL is also called gamma-corrected APL in IEC 62087-2 [4]. In addition, it is noted
that the tone rendering curve may not have a power law function with a well-defined exponent (gamma).
3.1.3
APL loading
influence of average picture level on display performance, for example luminance
3.1.4
chromaticity difference
geometric distance between two colour coordinates in a CIE chromaticity diagram, usually the
CIE 1976 chromaticity diagram
3.1.5
chromaticity gamut area
colour gamut area
maximum area of chromaticity reproducible by a display

Note 1 to entry: "Colour gamut area" has been used in textbooks, industry, and the market for a long time. However,
the CIE (eilv.cie.co.at) indicates that the term "colour gamut" should be regarded as a volume in a colour space.
Therefore, a two-dimensional representation should be described as a chromaticity gamut area.
3.1.6
direct view
non-projection display technology where the image rendering surface is viewed directly without
any optical components between the viewer and the surface
3.2 Abbreviated terms
APL average picture level
CAT chromatic adaption transform
CCT correlated colour temperature
CIE Commission Internationale de L’Eclairage (International Commission on
Illumination)
CIELAB CIE 1976 (L*a*b*) colour space
CMY cyan, magenta, and yellow
DUT device under test
EOTF electro-optic transfer function
HDR high dynamic range
LCD liquid crystal display
LED light-emitting diode
LMD light measuring device
OETF opto-electronic transfer function
RGB red, green, and blue
RGBCMY red, green, blue, cyan, magenta, and yellow
SDR standard dynamic range
sRGB a standard RGB colour space defined in IEC 61966-2-1
SPD spectral power distribution
UCS uniform chromaticity scale

4 General
4.1 Measured basic quantities
The basic quantities for luminance and chromaticity can be measured directly, for example with
photometers and colorimeters, or they can be obtained from measured spectra (i.e. the spectral
power distribution (SPD)) by a spectroradiometer. Spectroradiometers are generally more
accurate than photometers or colorimeters, and should be used when higher accuracy is needed.
Photometers and colorimeters allow for fast data acquisition as required for evaluation of optical
transitions (e.g. "switching times"). The acquisition of the spectral power distribution is usually
restricted to steady optical states.
4.2 Electrical driving of the display (depending on the nature of the display)
The electrical driving conditions of the display are as follows:
– driving voltage (waveform), current, frequency, etc.;
– RGB input (analogue, digital);
– test pattern (independent of display electrical interface).

– 12 – IEC 62977-2-1:2021 © IEC 2021
4.3 Data acquisition timing and display driving
4.3.1 Stationary measurements
After application of a new driving state (test pattern), a delay (wait) period is introduced for the
optical response to settle to a steady state before the measurement is carried out.
4.3.2 Properties of display under test
The physics of the display itself or the signal processing measures can affect the optical
response (image), for example via luminance loading (luminance dependence on APL). The
display to be measured shall be checked for this effect and the test patterns used during the
measurement procedure shall be chosen and applied accordingly.
5 Standard measuring conditions
5.1 Standard measuring environmental conditions
Measurements shall be carried out under the standard environmental conditions:
– temperature: 25 °C ± 3 °C,
– relative humidity: 25 % to 85 %,
– atmospheric pressure: 86 kPa to 106 kPa.
When different environmental conditions are used, they shall be noted in the report.
5.2 Standard measuring darkroom conditions
The luminance contribution from unwanted background illumination reflected off the test display
shall be less than 1/20 of the display’s black state luminance. The reflected background
luminance can be approximated by turning off the display. When the reflected background
luminance and total (reflected plus black) luminance are greater than the sensitivity limit of the
LMD, then it is possible to calculate the black luminance by subtracting the background
luminance from the total luminance. If the reflected background luminance or total luminance
are similar to the sensitivity limit of the LMD, this shall be reported. In cases where the display
has a very low luminance black state, a stray light elimination tube (according to ISO 9241-305)
should be used to minimize the contribution of the background illumination. This method can
be used to estimate the reflected luminance from the black state luminance.
NOTE Blackout curtains are a solution for reducing the reflection from the DUT.
5.3 Standard setup conditions
5.3.1 General
Standard setup conditions are given in 5.3. Any deviations from these conditions shall be
reported.
5.3.2 Adjustment of display
The display shall be configured to the specified settings, and the settings recorded in the test
report. These settings shall be held constant for all measurements. It is important, however, to
make sure that not only the adjustments are kept constant, but also that the resulting physical
quantities remain constant during the measurement. This is not automatically the case because
of, for example, warm-up effects or auto-dimming features. Any automatic luminance or gain
control shall be turned off. Otherwise it should be noted in the report. The ambient light (or
brightness) control (ABC), which can reduce the display luminance level with dim ambient
illumination, shall be turned off. If that is not possible, it is recommended to set it to turn on no
lower than 300 lx to minimize the influence of the ABC. The state of the ABC shall be reported.
In addition, if the display has an auto-dimming feature which reduces the display luminance of

a static image after a prolonged time, then at least an 8 s black frame shall be rendered prior
to rendering and measuring the desired test pattern. The measurements shall be completed
before the dimming feature is triggered. When the display has the option to be set for different
viewing modes, the viewing mode shall be defined by the test specification, and be used with
consistency for all measurements. Additional viewing modes can also be measured. The
viewing mode used during testing shall be reported. The display should be operated in a mode
that does not have overscan.
5.3.3 Starting conditions of measurements
Measurements shall be started after the displays and measuring instruments achieve stability.
The DUT shall be turned on first and operated for at least 30 min prior to the measurement.
Some display technologies may need a loop of colour patterns rendered on the screen during
the warm-up period. Sufficient warm-up time has been achieved when the luminance of the test
feature to be measured varies by less than ±3 % over the entire measurement period (e.g.
uniformity measurements) for a given display image.
5.3.4 Conditions of measuring equipment
5.3.4.1 General conditions
Optical properties of displays shall generally be expressed in photometric or colorimetric units
using the CIE 1931 standard colorimetric 2° observer (according to ISO/CIE 11664-1).
Luminance can be measured by a photometer, and CIE tristimulus values (X, Y, Z) or CIE
chromaticity coordinates by a colorimeter. A spectroradiometer can also obtain photometric and
colorimetric values through a numerical conversion of the measured spectral radiance data (see
for example [5]). The following requirements are given for these instruments.
The LMD shall be a luminance meter, colorimeter, or a spectroradiometer. For DUTs that have
sharp spectral peak full-width-at-half-maximums (FWHMs) smaller than 20 nm, such as LCDs
with fluorescent lamp backlights or LEDs with narrow-peak phosphors, quantum-dot phosphors,
or narrow-spectrum OLEDs, a spectroradiometer should be used. A filter colorimeter should
generally not be used for light sources with sharp spectral peaks. If a colorimeter is used, it
shall be calibrated with the measured colorimetry values obtained from a narrow bandwidth
spectroradiometer. Even with this procedure, the colorimeter will give lower accuracy results
than the spectroradiometer. Report the characteristics of the spectroradiometer (as given in
CIE 233) which is used for calibration. For light sources with sharp spectral peaks, the maximum
bandwidth of the spectroradiometer shall be ≤ 5 nm. In those cases, the wavelength accuracy
shall be within ±0,3 nm. The spectroradiometer shall be capable of measuring spectral radiance
over at least the 380 nm to 780 nm wavelength range, with a maximum bandwidth of 10 nm for
smooth broadband spectra (i.e. broad spectrum with no sharp spikes).
Care should be taken to ensure that the LMD has enough sensitivity and dynamic range to
perform the required task. Before measuring the DUT, it is recommended to check the LMD
specification.
The following additional best practices shall be followed:
a) The LMD shall be focused on the image plane of the display and generally al
...