IEC 62977-2-2:2020

Electronic displays - Part 2-2: Measurements of optical characteristics - Ambient performance

IEC 62977-2-2:2020(E) specifies standard measurement conditions and measuring methods for determining the optical characteristics of electronic displays under indoor and outdoor illumination conditions. Standard illumination geometries are specified and the reflection properties of flat screens are determined under those conditions. Reference illumination levels and spectra are used to estimate the photometric and colorimetric characteristics of electronic displays under the same conditions. These methods apply to emissive, transmissive, and reflective displays, or combinations thereof, that render real 2D images on a flat screen.

General Information

• Status: Published
• Publication Date: 20-Sep-2020
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 31.120 - Electronic display devices
• ICS: 31.260 - Optoelectronics. Laser equipment
• Technical Committee: TC 110 - Electronic displays
• Current Stage: PPUB - Publication issued
• Completion Date: 21-Sep-2020

Standards Content (sample)

IEC 62977-2-2
Edition 1.0 2020-09
INTERNATIONAL
STANDARD
colour
inside
Electronic displays –
Part 2-2: Measurements of optical characteristics – Ambient performance
IEC 62977-2-2:2020-09(en)
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IEC 62977-2-2
Edition 1.0 2020-09
INTERNATIONAL
STANDARD
colour
inside
Electronic displays –
Part 2-2: Measurements of optical characteristics – Ambient performance
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.120; 31.260 ISBN 978-2-8322-8816-0

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC 62977-2-2:2020 © IEC 2020
CONTENTS

FOREWORD ........................................................................................................................... 5

INTRODUCTION ..................................................................................................................... 7

1 Scope .............................................................................................................................. 9

2 Normative references ...................................................................................................... 9

3 Terms, definitions, abbreviated terms and symbols .......................................................... 9

3.1 Terms and definitions .............................................................................................. 9

3.2 Abbreviated terms ................................................................................................. 10

3.3 Symbols ................................................................................................................ 10

4 Standard measuring conditions ...................................................................................... 11

4.1 Standard measuring environmental conditions ...................................................... 11

4.2 Viewing direction and light source coordinate system ............................................ 12

4.3 Standard lighting conditions .................................................................................. 12

4.3.1 General ......................................................................................................... 12

4.3.2 Standard measuring darkroom conditions ...................................................... 13

4.3.3 Standard ambient illumination ........................................................................ 13

4.3.4 Standard illumination geometries ................................................................... 14

4.4 Standard setup conditions ..................................................................................... 20

4.4.1 General ......................................................................................................... 20

4.4.2 Adjustment of display .................................................................................... 20

4.4.3 Starting conditions of measurements ............................................................. 21

4.4.4 General conditions of measuring equipment .................................................. 21

4.5 Reflection standards ............................................................................................. 22

4.5.1 General ......................................................................................................... 22

4.5.2 Diffuse reflectance standard .......................................................................... 22

4.6 Locations of measurement field............................................................................. 23

5 Darkroom luminance and spectra................................................................................... 23

5.1 General ................................................................................................................. 23

5.2 Test pattern .......................................................................................................... 23

5.2.1 General ......................................................................................................... 23

5.2.2 Simple box test patterns ................................................................................ 23

5.2.3 Multi-colour test pattern ................................................................................. 24

5.2.4 Measuring conditions ..................................................................................... 25

5.2.5 Measuring method ......................................................................................... 25

6 Reflection measurements .............................................................................................. 26

6.1 General ................................................................................................................. 26

6.2 Measuring conditions ............................................................................................ 26

6.3 Measuring the hemispherical diffuse reflectance ................................................... 27

6.4 Measuring the reflectance factor for a directed light source................................... 28

7 Ambient optical performance ......................................................................................... 30

7.1 General ................................................................................................................. 30

7.2 Ambient contrast ratio ........................................................................................... 30

7.2.1 General ......................................................................................................... 30

7.2.2 Measuring conditions ..................................................................................... 30

7.2.3 Measuring method ......................................................................................... 30

7.3 Ambient display colour .......................................................................................... 31

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IEC 62977-2-2:2020 © IEC 2020 – 3 –

7.3.1 General ......................................................................................................... 31

7.3.2 Measuring conditions ..................................................................................... 31

7.3.3 Measuring method ......................................................................................... 31

7.4 Ambient colour gamut volume ............................................................................... 33

7.4.1 General ......................................................................................................... 33

7.4.2 Measuring conditions ..................................................................................... 34

7.4.3 Measuring method ......................................................................................... 34

Annex A (normative) RGB boundary colours for CIELAB gamut volume measurements ....... 37

A.1 General ................................................................................................................. 37

A.2 Equally-spaced 98 boundary colours on the RGB cube ......................................... 37

A.3 Recommended 602 boundary colours on the RGB cube ........................................ 40

Annex B (informative) Calculation method for CIELAB gamut volume................................... 54

B.1 Purpose ................................................................................................................ 54

B.2 Procedure for calculating the colour gamut volume ............................................... 54

B.3 Number of sampled colours .................................................................................. 55

B.4 RGB cube surface subdivision method for CIELAB gamut volume calculation ....... 55

B.4.1 General ......................................................................................................... 55

B.4.2 Assumption .................................................................................................... 55

B.4.3 Uniform RGB grid algorithm ........................................................................... 55

B.4.4 Software example execution .......................................................................... 57

Bibliography .......................................................................................................................... 67

Figure 1 – Representation of the viewing direction (direction of measurement) and

coordinate system used for light source configuration ........................................................... 12

Figure 2 – Illustrated examples for directional illumination .................................................... 15

Figure 3 – Example of the measuring setup using directional illumination where

θ = 40° and θ = 30° .......................................................................................................... 16

S R

Figure 4 – Example of ring light illumination measuring setup where θ ± ∆ = 35 ± 5

and θ = 20° ......................................................................................................................... 17

Figure 5 – Detailed schematic of ring light characteristics ..................................................... 18

Figure 6 – Example of measurement geometries for hemispherical illumination using

an integrating sphere (left) or sampling sphere (right) ........................................................... 19

Figure 7 – Layout diagram of measurement setup ................................................................. 22

Figure 8 – Example of centre box test patterns using the standard 4 % and

10 % area boxes ................................................................................................................... 24

Figure 9 – Standard medium APL RGBCMYWx test pattern used for centre luminance

and spectra measurements with 25 % APL ........................................................................... 25

Figure 10 – Example of the range in colours produced by a display ...................................... 36

Figure B.1 – Analysis flow chart for calculating the CIELAB gamut volume ........................... 54

Figure B.2 – Example of tessellation using 5 × 5 grid of surface colours on the

RGB cube ............................................................................................................................. 57

Figure B.3 – Example of tessellation for the RGB cube using a 3 × 3 grid ............................. 59

Figure B.4 – Example of tessellation for the CIELAB gamut volume using a 3 × 3 grid .......... 59

Table 1 – Measurement structure from optical quantities to evaluation and to results

(top down) .............................................................................................................................. 8

Table 2 – Summary of symbols ............................................................................................. 11

Table 3 – Eigenvalues M and M for CIE daylight Illuminants D50, D65, and D75 ................ 28

1 2
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– 4 – IEC 62977-2-2:2020 © IEC 2020
Table A.1 – Equally-spaced 98 RGB boundary colours used for CIELAB gamut volume

measurements ...................................................................................................................... 38

Table A.2 – Recommended RGB boundary colours used for CIELAB colour gamut

volume measurements .......................................................................................................... 41

Table B.1 – Example RGB boundary colours used to demonstrate how the CIELAB

colour gamut volume can be calculated ................................................................................ 58

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IEC 62977-2-2:2020 © IEC 2020 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRONIC DISPLAYS –
Part 2-2: Measurements of optical characteristics –
Ambient performance
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

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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

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6) All users should ensure that they have the latest edition of this publication.

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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

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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 62977-2-2 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
110/1213/FDIS 110/1232/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.
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Future standards in this series will carry the new general title as cited above. Titles of existing

standards in this series will be updated at the time of the next edition.

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.
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IEC 62977-2-2:2020 © IEC 2020 – 7 –
INTRODUCTION

This document describes the common optical measurement methods applicable in the field of

electronic display devices, which overlap with some of the parts of existing documents

developed inside TC 110 (IEC 61747-6-2 [17] , IEC 62341-6-2 [18], IEC 61988-2-2 [19],

IEC 62715-5-1 [20], IEC 62679-3-1 [21]), 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 61747-6-2 [17], IEC 62341-6-2

[18], IEC 61988-2-2 [19], IEC 62715-5-1 [20], IEC 62679-3-1 [21]). The existing standards

documents will be revised in their maintenance time and they will refer to this document to the

largest extent.

All documents in IEC TC 110 that are concerned with the measurement of optical properties

of electronic display devices under ambient illumination 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 methods (COMMs) 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

documents 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.

_____________
Numbers in square brackets refer to the Bibliography.
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– 8 – IEC 62977-2-2:2020 © IEC 2020
Table 1 – Measurement structure from optical quantities
to evaluation and to results (top down)
Test pattern,
Illumination Temperature,
Variables Time Location Direction electrical driving,
conditions humidity
input signal
(x, y) (θ, φ)
Data
sampling Fast Slow Slow Slow Slow √
condition
Evaluation

Results Transitions Temporal Lateral Directional Static pattern, √ Darkroom, √ Standard

from one stability uniformity uniformity environment √
Characteristic Indoor,
optical state (uniformity)
function (electro-
to another
Outdoor
optic transfer
state (for
function, EOTF)
example from
test-pattern-1
Characteristic
to test-
values (e.g.
pattern-2)
threshold,
saturation)
Evaluation Turn-on, Luminance, √
1st order turn-off,
Contrast, √
delay
chromaticity, √
(latency)
time periods,
Threshold,
temporal
saturation values,
modulations
steepness of
transitions, etc.
Evaluation Flicker EOTF from which
2nd order prediction,
the exponent γ is
moving
evaluated
picture
Chromaticity/ colour
response
gamut area,
time, etc.
Colour gamut
volume, √
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IEC 62977-2-2:2020 © IEC 2020 – 9 –
ELECTRONIC DISPLAYS –
Part 2-2: Measurements of optical characteristics –
Ambient performance
1 Scope

This part of IEC 62977 specifies standard measurement conditions and measuring methods

for determining the optical characteristics of electronic displays under indoor and outdoor

illumination conditions. Standard illumination geometries are specified and the reflection

properties of flat screens are determined under those conditions. Reference illumination

levels and spectra are used to estimate the photometric and colorimetric characteristics of

electronic displays under the same conditions. These methods apply to emissive,

transmissive, and reflective displays, or combinations thereof, that render real 2D images on

a flat screen.
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 (IEV) – Part 845: Lighting

IEC 61966-2-1, Multimedia systems and equipment – Colour measurement and management

– Part 2-1: Colour management – Default RGB colour space – sRGB
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

ISO 15076-1:2010, Image technology colour management – Architecture, profile format and

data structure – Part 1: Based on ICC.1:2010
CIE 15, Colorimetry
CIE 168, Criteria for the evaluation of extended-gamut colour encoding
3 Terms, definitions, abbreviated terms and symbols
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
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– 10 – IEC 62977-2-2:2020 © IEC 2020
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 [14]. 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
3.2 Abbreviated terms
APL pre-gamma average picture level
CCT correlated colour temperature
CIE Commission Internationale de L’Eclairage (International Commission on
Illumination)
CIELAB CIE 1976 (L*a*b*) colour space
DUT device under test
EOTF electro-optic transfer function
FWHM full-width-at-half-maximum
ILU integrated lighting unit (e.g. an edge-lit front guide plate)
LCD liquid crystal display
LED light emitting diode
LMD light measuring device
OLED organic light emitting diode
RGB red, green, and blue
SDR standard dynamic range
sRGB standard RGB colour space defined in IEC 61966-2-1
3.3 Symbols
A list of symbols used in this document is given in Table 2.
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IEC 62977-2-2:2020 © IEC 2020 – 11 –
Table 2 – Summary of symbols
Symbol Units Definition
E lx illuminance
-2 -1
E(λ) W∙m ∙nm spectral irradiance
-2 -1

E (λ) W∙m ∙nm spectral irradiance from a directed light source at normal incidence

dir
spectral irradiance of a CIE standard illuminant from a directed light
-2 -1
E (λ) W∙m ∙nm
CIE,dir
source at normal incidence
-2 -1
W∙m ∙nm spectral irradiance from a hemispherical diffuse light source
E (λ)
hemi
spectral irradiance of a CIE standard illuminant from a
-2 -1
E (λ) W∙m ∙nm
CIE,hemi
hemispherical diffuse light source
R luminous reflectance factor for a rendered display colour Q
R (λ) spectral reflectance factor for a rendered display colour Q
luminous reflectance or diffuse reflectance for a rendered display
colour Q
spectral reflectance for a rendered display colour Q
ρ (λ)
L cd⋅m darkroom luminance for a rendered display colour Q
−1 −2 −1
L (λ) W⋅sr ⋅m ⋅nm darkroom spectral radiance for a rendered display colour Q
ambient spectral radiance, including reflected and darkroom emitted
−1 −2 −1
L (λ) W⋅sr ⋅m ⋅nm
Q amb
light, for a rendered display colour Q
reflected spectral radiance when the reflection coefficients are
−1 −2 −1
L (λ) W⋅sr ⋅m ⋅nm
Refl
independent of the rendered display colour Q
CIE tristimulus values of the rendered display colour Q in a
X , Y , and Z cd⋅m for Y
Q Q Q Q
darkroom
X , Y equivalent CIE tristimulus values, including reflected and darkroom
Q,amb Q,amb,
cd⋅m for Y
Q,amb
and Z emitted light, for a rendered display colour Q
Q,amb
CIE 1931 chromaticity coordinates of the rendered display colour Q
x , y
Q Q
in a darkroom
equivalent CIE 1931 chromaticity coordinates, including reflected
x , y
Q,amb Q,amb
and darkroom emitted light, for a rendered display colour Q
4 Standard measuring conditions
4.1 Standard measuring environmental conditions

Measurements shall be carried out under the following 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.

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4.2 Viewing direction and light source coordinate system

The viewing direction is the direction under which the observer looks at the point of interest

on the display under test (DUT). During the measurement, the light measuring device (LMD)

simulates the observer, by aiming the LMD at the point of interest on the DUT from the

viewing direction. The viewing direction is defined by two angles: the angle of inclination θ

(relative to the surface normal of the DUT) and the angle of rotation φ (also called azimuth

angle) as illustrated in Figure 1. Although the azimuth angle is measured in the counter-

clockwise direction, it is r
...