IEC 62341-6-3:2017

IEC 62341-6-3 ®
Edition 2.0 2017-11
INTERNATIONAL
STANDARD
colour
inside
Organic light emitting diode (OLED) displays –
Part 6-3: Measuring methods of image quality
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IEC 62341-6-3 ®
Edition 2.0 2017-11
INTERNATIONAL
STANDARD
colour
inside
Organic light emitting diode (OLED) displays –

Part 6-3: Measuring methods of image quality

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.260 ISBN 978-2-8322-4977-2

– 2 – IEC 62341-6-3:2017 © IEC 2017
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms, definitions, and abbreviated terms . 6
3.1 Terms and definitions . 6
3.2 Abbreviated terms . 7
4 Standard measuring equipment and coordinate system . 7
4.1 Light measuring device . 7
4.2 Viewing direction coordinate system . 8
4.3 Standard measuring environmental conditions . 9
4.4 Power supply . 9
4.5 Warm-up time . 10
4.6 Standard measuring dark-room conditions . 10
4.7 Standard set-up conditions . 10
5 Measuring methods . 10
5.1 Measuring methods for spatial image quality . 10
5.1.1 Viewing angle . 10
5.1.2 Colour characteristics . 17
5.1.3 Crosstalk . 22
5.1.4 Static image resolution . 25
5.2 Measuring methods for temporal image quality . 30
5.2.1 Flicker . 30
5.2.2 Grey-to-grey response time . 34
Annex A (informative) Simple matrix method for correcting the stray light of imaging
instruments . 36
A.1 Purpose . 36
A.2 Measuring method . 36
Annex B (informative) Measuring the moving picture perceptual resolution of a display . 38
B.1 Purpose . 38
B.2 Measuring conditions . 38
B.2.1 Measuring equipment . 38
B.2.2 Requirements for the camera system . 38
B.2.3 Requirements for test pattern . 38
B.2.4 Parameters for measuring condition . 40
B.2.5 Measurement procedure . 40
Bibliography . 42

Figure 1 – Representation of the viewing direction . 9
Figure 2 – DUT installation conditions . 10
Figure 3 – Conceptual geometry used for measuring the viewing angle range . 11
Figure 4 – 4 % window pattern for half luminance angle . 12
Figure 5 – Test pattern for gamma measurement . 14
Figure 6 – Example of linear regression of log(△L ) versus log(△V ) at normal
i j
direction (0°) . 15
Figure 7 – 4 % window pattern for measuring the ‘red’ primary colour . 18

Figure 8 – 4 % window pattern for each G, B, C, M, Y colour . 18
Figure 9 – Test pattern for gamut change of the colour scale . 20
Figure 10 – Example of the measurement results . 21
Figure 11 – Test pattern for colour desaturation . 22
Figure 12 – Standard measurement positions . 23
Figure 13 – Luminance measurement of 4 % window at P . 23
Figure 14 – Luminance measurement at P with windows A , A , A and A . 24
0 W1 W2 B3, B4
Figure 15 – Luminance measurement at P with windows A , A , A and A . 25
0 W5 W8 B5 B8
Figure 16 – Test pattern for effective resolution . 26
Figure 17 – Example of luminance window for one-line grilled input . 28
Figure 18 – Contrast modulation measurement . 29
Figure 19 – Apparatus arrangement . 30
Figure 20 – Temporal contrast sensitivity function . 32
Figure 21 – Example of flicker modulation waveform . 33
Figure 22 – Example of response time waveform . 35
Figure A.1 – Result of spatial stray light correction for an imaging photometer . 37
Figure B.1 – Example of grey levels . 39
Figure B.2 – Example of frequency based on full HD resolution . 39
Figure B.3 – Example of test signal for full HD . 40
Figure B.4 – Example of captured image and one-dimensional data . 41
Figure B.5 – Example of motion blur threshold point . 41

Table 1 – Working example for gamma distortion from viewing direction . 15
Table 2 – Reference areas for the colour reproduction range . 16
Table 3 – Example of measurement results for colour fidelity . 20
Table 4 – Example of measurement results for gamut change of colour scale . 20
Table 5 – Example of measurement results for 1 x 1 grilled colour desaturation . 21
Table 6 – Temporal contrast sensitivity function . 31
Table 7 – Example of reporting form of grey-to-grey response time . 35
Table B.1 – Six different grey levels . 39

– 4 – IEC 62341-6-3:2017 © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ORGANIC LIGHT EMITTING DIODE (OLED) DISPLAYS –

Part 6-3: Measuring methods of image quality

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
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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 62341-6-3 has been prepared by IEC technical committee 110:
Electronic display devices.
This second edition cancels and replaces the first edition published in 2012. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the measuring method for viewing angle has been modified. Measurement of the half
luminance angle, gamma distortion, and directional colour variation is added;
b) measurement method for colour characteristics is added;
c) additional explanation is added in static image resolution clause;
d) moving image resolution clause has been moved to Annex B.

The text of this International Standard is based on the following documents:
FDIS Report on voting
110/901/FDIS 110/923/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 the parts in the IEC 62341 series, under the general title Organic light emitting
diode (OLED) 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.
A bilingual version of this publication may be issued at a later date.
The contents of the corrigendum of October 2019 have been included in this copy.

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.
– 6 – IEC 62341-6-3:2017 © IEC 2017
ORGANIC LIGHT EMITTING DIODE (OLED) DISPLAYS –

Part 6-3: Measuring methods of image quality

1 Scope
This part of IEC 62341 specifies the standard measurement conditions and measuring
methods for determining the image quality of organic light emitting diode (OLED) display
panels and modules.
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 62341-1-2:2014, Organic light emitting diode (OLED) displays – Part 1-2: Terminology
and letter symbols
3 Terms, definitions, and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62341-1-2 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
average picture level
APL
average loading percentage of display sub-pixels based on input signal levels
3.1.2
static image resolution
maximum number of lines that can be adequately distinguished horizontally and vertically
across the screen for static image signal inputs
Note 1 to entry: The unit of resolution is line, but pixel is also available as the unit of resolution.
3.1.3
colour fidelity
ability to reproduce the intended colour
3.1.4
colour desaturation
difference in chromaticity coordinates between solid colour and grilled pattern caused by
image sharpening algorithm
3.1.5
directional gamma distortion
ratio of gamma differences between the perpendicular and other viewing direction
3.1.6
colour scale
range of luminance levels between maximum luminance and minimum luminance for the
primary colour
3.2 Abbreviated terms
APL average picture level
CCD charge coupled device
CFF critical flicker frequency
CIE Commission Internationale de l’Eclairage (International Commission on
Illumination)
CIELAB CIE 1976 (L*a*b*) colour space
DUT device under test
HVS human visual system
LED light emitting diode
LMD light measuring device
MPPR moving picture perceptual resolution
OLED organic light emitting diode
PSF point spread function
RGB red, green, blue
SDF stray light distribution function
SLSF spectral line spread function
4 Standard measuring equipment and coordinate system
4.1 Light measuring device
The system configuration and/or operating conditions of the measuring equipment shall
comply with the structure specified in each item.
To ensure reliable measurements, the following requirements apply to the light measuring
equipment:
1) Luminance meter [1] : the instrument's spectral responsivity shall comply with the CIE
photonic luminous efficiency function with a CIE-f1’ value no greater than 3 % [2]; the
relative luminance uncertainty of measured luminance (relative to CIE Illuminant A source)
shall not be greater than 4 % for luminance values over 0,1 cd/m and not greater than
10 % for luminance values 0,1 cd/m and below.
2) Colorimeter: the detector’s spectral responsivity shall comply with the colour matching
functions for the CIE 1931 standard colorimetric observer with a colorimetric accuracy of
0,002 for the CIE chromaticity coordinates x and y (relative to CIE Illuminant A source) for
luminance values over 1 cd/m . A correction factor can be used for the required accuracy
by application of a standard source with similar spectral distribution as the display to be
measured.
___________
Numbers in square brackets refer to the Bibliography.

– 8 – IEC 62341-6-3:2017 © IEC 2017
3) Spectroradiometer: the wavelength range shall be at least from 380 nm to 780 nm, and
the wavelength scale accuracy shall be less than 1 nm. The relative luminance uncertainty
of measured luminance (relative to CIE Illuminant A source) shall not be greater than 4 %
for luminance values over 0,1 cd/m and not greater than 10 % for luminance values
0,1 cd/m and below. Note that errors from spectral stray light within a spectroradiometer
can be significant and shall be corrected. A simple matrix method may be used to correct
the stray light errors, by which stray light errors can be reduced by one to two orders of
magnitudes. Details of this correction method are discussed in [3].
4) Goniophotometric mechanism: the DUT or LMD can be driven rotating around a horizontal
axis and vertical axis; angle accuracy shall be better than 0,5°.
5) Fast-response photometer: the linearity shall be better than 0,5 % and the frequency
response higher than 1 kHz.
4.2 Viewing direction coordinate system
The viewing direction is the direction in which the observer looks at the spot of interest on the
DUT (see also IEC 62341-1-2:2014, Figure A.2). During the measurement, the LMD replaces
the observer, looking from the same direction at a specified spot (i.e. measuring spot,
measurement field) on the DUT. The viewing direction is conveniently defined by two angles:
the angle of inclination θ (related to the surface normal of the DUT) and the angle of rotation φ
(also called azimuth angle) as illustrated in Figure 1. The azimuth angle is related to the
directions on a watch-dial as follows: φ = 0° is referred to as the 3-o'clock direction ("right"),
φ = 90 ° as the 12-o'clock direction ("top"), φ = 180° as the 9-o'clock direction ("left") and
φ = 270 ° as the 6-o'clock direction ("bottom").

Normal direction
θ = 0°
Viewing direction
(θ, φ)
z
θ
12 o'clock
φ = 90°
Upside
y
φ
x' x
9 o'clock 3 o'clock
φ = 180° φ = 0°
Display plane
y'
Down side
6 o'clock
z'
φ = 270°
θ : incline angle from normal direction
φ : azimuth angle
IEC
Key
3 o’clock: right edge of the screen as seen from the perspective of the user
6 o’clock: bottom edge of the screen as seen from the perspective of the user
9 o’clock: left edge of the screen as seen from the perspective of the user
12 o’clock: top edge of the screen as seen from the perspective of the user
NOTE This coordination is defined by the angle of inclination and the angle of rotation (azimuth angle) in a polar
coordinate system.
Figure 1 – Representation of the viewing direction
4.3 Standard measuring environmental conditions
Measurements shall be carried out under the standard environmental conditions:
• temperature: 25 ºC ± 3 ºC,
• relative humidity: 25 % RH to 85 % RH,
• atmospheric pressure: 86 kPa to 106 kPa.
When different environmental conditions are used, they shall be noted in the measurement
report.
4.4 Power supply
The power supply for driving the DUT shall be adjusted to the rated voltage ± 0,5 %. In
addition, the frequency of the power supply shall provide the rated frequency ± 0,2 %.

– 10 – IEC 62341-6-3:2017 © IEC 2017
4.5 Warm-up time
Measurements shall be carried out after sufficient warm-up. Warm-up time is defined as the
time elapsed from when the supply source is switched on, and a 100 % grey level of input
signal is applied to the DUT, until repeated measurements of the display show a variation in
luminance of no more than 2 % per minute and 5 % per hour.
4.6 Standard measuring dark-room conditions
The luminance contribution from the background illumination reflected off the test display
shall be < 0,01 cd/m . If these conditions are not satisfied, then background subtraction is
required and it shall be noted in the measurement report. In addition, if the sensitivity of the
LMD is inadequate to measure these low levels, then the lower limit of the LMD shall be noted
in the measurement report.
4.7 Standard set-up conditions
By default, the display shall be installed in the vertical position (Figure 2a)), but the horizontal
alternative (Figure 2b)) is also allowed. When the latter alternative is used, it shall be noted in
the measurement report.
Luminance, contrast and chromaticity of the white field and other relevant parameters of the
displays have to be adjusted to nominal status in the detailed specification and they shall be
noted in the measurement report. When there is no level specified, the maximum contrast
and/or luminance level shall be used. These adjustments shall be held constant for all
measurements, unless noted otherwise in the measurement report. Additional conditions are
specified separately for each measuring method.
12 o’clock
φ = 90°
θ = 0°
y LMD
Vertical
12 o’clock
z
φ = 90°
Vertical
9 o’clock
(normal) y
φ = 180°
Horizontal
9 o’clock
Horizontal
φ = 180°
x
3 o’clock
Normal
x
φ = 0°
3 o’clock
z
φ = 0°
LMD
θ = 0°
6 o’clock
6 o’clock
φ = 270°
φ = 270°
IEC IEC
a) Primary installation b) Alternative installation
Figure 2 – DUT installation conditions
5 Measuring methods
5.1 Measuring methods for spatial image quality
5.1.1 Viewing angle
5.1.1.1 Purpose
The purpose of this method is to measure the viewing angle of an OLED display module in the
horizontal (φ = 0˚, φ = 180˚) and vertical (φ = 90˚, φ = 270 ) viewing direction.

5.1.1.2 Measuring conditions
Standard measuring is implemented under standard dark-room and set-up conditions.
5.1.1.3 Set-up
For this measurement, the LMD and DUT shall be set up as follows:
1) Apparatus: an LMD to measure luminance and chromaticity of the DUT; a driving power
source; a driving signal equipment; a geometric mechanism illustrated in Figure 3.
2) Mount the display and LMD in a mechanical system that allows the display to be
measured along its vertical and horizontal planes, which lie normal to the display surface.
Figure 3 illustrates the geometry to be used in this measurement. The angle relative to the
display normal in the horizontal plane, the 3 o’clock and 9 o’clock direction, is expressed
as θ , and the angle in the vertical plane, the 6 o’clock and 12 o’clock direction, by θ .
H V
Either the display can be tilted to scan both planes, or the LMD can be moved within these
planes. During the measuring procedure, the LMD shall be directed at the same field of
measurement for all angles of inclination. In either case, the centre of the measurement
field shall remain at the same location on the DUT surface for all angles of inclination. The
angular positioning of the display in the goniophotometric system shall be accurate to
±0,5º, and the measuring range shall be implemented from -90° to +90° both in the
vertical and horizontal planes.
Vertical y
Viewing
θ
V
direction
θ
V
Horizontal
x
θ
Normal
H
z
θ
LMD H
IEC IEC
a) Geometric structure b) Geometric system
of display to be measured
Figure 3 – Conceptual geometry used for measuring the viewing angle range
3) Align the LMD perpendicular to the display surface (θ = 0, φ = 0), and position it to the
centre of the display.
5.1.1.4 Measurement of the half luminance angle
The measurement shall be as follows:
1) Apply a 4 % window size white screen with a 100 % signal level (R = G = B = 255 for an 8-
bit input signal) to the DUT as shown in Figure 4.
2) Measure the centre luminance (L ) perpendicular to the display surface (θ = 0°, φ = 0°).
The measurement area shall cover at least 500 pixels, or demonstrate equivalent results
with fewer sampled pixels.
3) Take luminance (L , ) measurements as the LMD steps through the various angles in the
0φ
horizontal (φ = 0°, φ = 180°) and vertical (φ = 90°, φ = 270°) viewing planes. The
measurement area should not expand past the 4 % window at large viewing directions.

– 12 – IEC 62341-6-3:2017 © IEC 2017
4) Record the change in luminance from the perpendicular direction. The luminance change
is defined in terms of the luminance ratio:
L
θ,φ
LR = (1)
θ,φ
L
The half luminance angle can be defined as an angle when the luminance ratio (LR),
calculated using Formula (1), equals 50 %.
5) Determine the half luminance angles in each of the four viewing directions (φ = 0°, φ =
180°, φ = 90°, φ = 270°).
2H/5 H/5
H
IEC
Figure 4 – 4 % window pattern for half luminance angle
NOTE Other measurement systems, such as conoscopic instruments, can also be used for the viewing angle
range measurement, if equivalent results can be demonstrated.
5.1.1.5 Measurement of colour difference
The measurement method shall be as follows:
1) Apply a 4 % window size ‘white’, ‘red’, ‘green’, and ‘blue’ screen with a 100 % signal level
(R = G = B = 255 for ‘white’; R = 255, G = B = 0 for ‘red’; G = 255, R = B = 0 for ‘green’;
B = 255, R = G = 0 for ‘blue’) to the DUT.
2) Measure the centre CIE 1976 chromaticity coordinates (u’ , v’ ) perpendicular to the
0 0
display surface (θ = 0°, φ = 0°). The measurement area shall cover at least 500 pixels, or
demonstrate equivalent results with fewer sampled pixels.
3) Take chromaticity coordinate values as the LMD steps through the various angles in the
horizontal (φ = 0°, φ = 180°) and vertical (φ = 90, φ = 270°) viewing planes.
4) Record the change in chromaticity coordinates from the perpendicular direction. Colour
shifts with viewing angle are to be determined by a value from the colour difference
formula using the CIE 1976 uniform chromaticity scale. Furthermore any advanced colour
difference model such as CIE 94 and CIE 2000 can be used for this measurement.
2 2
Δu'v' = (u' −u' ) + (v' −v' ) (2)
θ,φ 0 θ,φ 0 θ,φ
2 2 2
* * *
     
ΔC ΔH
ΔL
* ab ab
   
 
ΔE = + + (3)
 
   
k S k S k S
L L C C H H
 
   
V
V/5 2V/5
where
2 2 2 2
* * * *
k = k = k = 1, S = 1, S = 1+ 0,045 a + b , S = 1+ 0,015 a + b
L C H L C 0 0 H 0 0
2 2 2
 ′   ′   ′   ′  ′ 
∆L ∆C ∆H ∆C ∆H
        
∆E = + + + R
00 T
        
K S K S K S K S K S
 L L  C C  H H  C C H H
and where
* * 2
0,015((L + L )/ 2− 50)
0 θ,φ
k = k = k = 1, S = 1+
L C H L
* * 2
20+ ((L + L )/ 2− 50)
0 θ,φ
'   
T= 1− 0,17cos(H − 30 )+ 0,24cos(2H')+ 0,32cos(3H'+6 )− 0,20cos(4H'−63 )
 
7 
 
C' H'−275

 
R =−2 sin 60 ⋅ exp(− (4)
 
T
7 7   
C' +25  25 
 
 
 
5) Determine the viewing angles in each of the four viewing directions (φ= 0°, φ=180°, φ=90°,
φ=270°) using specified chromaticity and colour difference values.
NOTE Other measurement systems, such as conoscopic instruments, can also be used for the viewing angle
range measurement, if equivalent results can be demonstrated.
5.1.1.6 Measurement of gamma distortion from viewing directions
The measurement method shall be as follows:
a) Apply the required input signal(s) using using either the 9- or 33-grey-level APL fixed
pattern to the DUT as shown in Figure 5.
b) Measure the centre luminance (L ) for specified grey levels perpendicular to the display
surface (θ = 0°, φ = 0°). The measurement area shall cover at least 500 pixels, or
demonstrate equivalent results with fewer sampled pixels.
c) Take luminance measurements (L ) of each specified grey level, as the LMD steps
θ,φ
through the various angles in the horizontal (φ = 0°, φ = 180°) and vertical (φ = 90°,
φ = 270°) viewing planes.
d) Calculate each gamma values from the measured directions.
1) For each luminance level j above black (j > 1) determine the net luminance as the
luminance increase over black,
ΔL = L − L j= 2,3,., M,
j j K,
(5)
.
where L = L = black, and M = 9 or 33 depending on the APL fixed pattern used in
K 1
Figure 5.
2) For each level j > 1,
– 14 – IEC 62341-6-3:2017 © IEC 2017
ΔV = V − V j= 2,3,., M,
j j 1,
(6)
where V is the grey level.
j
△L ) for each grey pattern (j > 1).
3) Calculate log(
j
4) Calculate log(△V ) for each grey level (j > 1).
j
5) Create a log-log plot between the log of the net luminance and the log of the net grey
level differences (or signal level differences).
6) Perform a linear regression of log(△L ) versus log(△V ) for j = 2,3,…,M, and record the
j j
correlation coefficient (see Figure 6).
e) Determine the gamma distortion values using Formula (7) for angles in the vertical and
horizontal planes (φ = 0°, φ = 180°, φ = 90°, φ = 270°).
γ−γ
i
(7)
(%)= ×100(%)
G
DR
γ
where γ is the reference gamma value which is the gamma value in the perpendicular
direction and γ are the gamma values measured from the different directional angles. The

i
directional gamma distortion ratio is the maximum of this set of values.
f) Report the measured data. Table 1 shows an example of the results.
IEC
a) 9-grey-level APL fixed pattern
IEC
b) 33-grey-level APL fixed pattern (33 grey levels: 0, 7, 15, 23, 31, 39, 47, 55, 63, 71, 79, 87, 95, 103, 111,
119, 127, 135, 143, 151, 159, 167, 175, 183, 191, 199, 207, 215, 223, 231, 239, 247, 255)
Figure 5 – Test pattern for gamma measurement

3,0
y = 2,289 2x –2,754 5
R = 0,999 9
2,5
2,0
1,5
1,0
0,5
1,0 1,5 2,0 2,5 3,0
Log (∆V )
j
IEC
Figure 6 – Example of linear regression of log(△L ) versus
i
log(△V ) at normal direction (0°)
j
Table 1 – Working example for gamma distortion from viewing direction
Reporting – Sample data
Grey-scale luminance and gamma values at various angles
Level Grey level, Luminance values from different angles L(θ,Ф)
designation
V
L(0,0) L L L L
j
(-20, 180) (20, 0) (20, 90) (-20, 270)
White (9) 255 555,7 181,2 180,3 160,8 164,7
Level 8 223 415,5 131,9 133,8 117,6 125.3
Level 7 191 293,6 102,7 105,8 93,9 101,3
Level 6 159 194,9 78,3 82,2 73.6 80
Level 5 127 115,1 54,7 58,7 53,8 58,2
Level 4 95 60,83 37,24 40,23 38,12 40,83
Level 3 63 23,53 22,47 24,14 24 25,06
Level 2 31 4,488 8,75 9,535 9,918 10,03
Black (1) 0 0,031 0,058 0,056 0,073 0,067
Gammas: 2,29 1,4 1,36 1,28 1,30
g (%) 39,86 40,61 44,1 43,23
i
43,2
g = max(g ) (%)
DR i
5.1.1.7 Measurement of directional gamut variation
The measurement method shall be as follows:
1) Apply a 4 % window size ‘red’, ‘green’, and ‘blue’ screen with a 100 % signal level
(R = 255, G = B = 0 for ‘red’; G = 255, R = B = 0 for ‘green’; and B = 255, R = G = 0 for
‘blue’) to the DUT.
Log (∆ L )
j
– 16 – IEC 62341-6-3:2017 © IEC 2017
2) Measure the centre chromaticity coordinates (u’ , v’ ) perpendicular to the display surface
0 0
(θ = 0°, φ = 0°). The measurement area shall cover at least 500 pixels, or demonstrate
equivalent results with fewer sampled pixels.
3) Take chromaticity coordinate values as the LMD steps through the various angles in the
horizontal (φ = 0°, φ = 180°) and vertical (φ = 90°, φ = 270°) viewing planes.
4) Calculate the colour gamut area, A, using Formula (8):
(u' −u' )(v' −v' )− (u' −u' )(v' −v' )
R B G B G B R B
A= (8)
5) Calculate the colour reproduction range, S, using Formula (9). The colour reproduction
range is defined as the percentage of the colour gamut area to the reference area.
Reference areas, A , are presented in Table 2. The colour reproduction range is reported
ref
with the reference area.
A
S= ×100
(9)
A
ref
Table 2 – Reference areas for the colour reproduction range
u’ v’ A (u’v’)
ref
R 0,4769 0,5285
NTSC G 0,0757 0,5757 0,0744
B 0,1522 0,1957
R 0,4507 0,5229
ITU BT.709
G 0,1250 0,5625 0,0649
(sRGB)
B 0,1754 0,1579
R 0,4414 0,5276
Adobe
G 0,0757 0,5757 0,0740
RGB
B 0,1754 0,1579
6) Determine the inclination angles (θ) in each of the four viewing directions (φ = 0°, φ = 180°,
φ = 90°, φ = 270°).
7) Calculate the colour gamut variation ratio, R, using Formula (10).
S
j
R= ×100 (10)
j
S
max
where S is the colour reproduction range of the colour scale j and S is the colour
j max
reproduction range of the maximum colour scale.
NOTE Other measurement systems, such as conoscopic instruments, can also be used for the viewing angle
range measurement, if equivalent results can be demonstrated.
___________
Adobe RGB is the trade name of a product supplied by Adobe Systems Incorporated.
This information is given for the convenience of users of this document and does not constitute an endorsement
by IEC of the product named. Equivalent products may be used if they can be shown to lead to the same results.

5.1.2 Colour characteristics
5.1.2.1 Purpose
The purpose of this method is to measure the colour characteristics of an OLED display in the
perpendicular viewing direction.
5.1.2.2 Measuring conditions
Standard measuring is implemented under standard dark-room and set-up conditions.
5.1.2.3 Basic set-up for colour performance
The DUT and LMD shall be set up as follows:
1) Apparatus: an LMD to measure luminance and chromaticity of the DUT; a driving power
source; a driving signal equipment; a geometric mechanism illustrated in Figure 3.
2) Mount the display and LMD in a mechanical system that allows the display to be
measured, normal to the display surface.
3) Input a signal to determine the CIE 1976 chromaticity coordinates (u’, v’), and generate
full ‘red’, ‘green’, and ‘blue’ screen with a 100 % signal level (R = 255, G = B = 0 for ‘red’;
G = 255, R = B = 0 for ‘green’; and B = 255, R = G = 0 for ‘blue’) on the display.
4) Align the LMD perpendicular to the display surface (θ = 0, φ = 0), and position it to the
centre of the display.
5.1.2.4 Measurement of colour fidelity
5.1.2.4.1 Purpose
The purpose of this method is to measure the colour fidelity for the primary and secondary
colours of an OLED display. Generally, colour difference metrics are used for evaluation of
the primary and secondary colours of a display. However, with recent standardization of a
wide colour gamut, new display modules which have a wide colour gamut are being
developed as well. Although a wide colour gamut display can produce vivid images, it would
result in unnatural colours. Colour fidelity metrics based on hue difference can accurately
predict the visual difference or unnatural feeling of images on a display module [22].
5.1.2.4.2 Set-up
For this measurement, the DUT shall be set up as follows:
a) Both a spectroradiometer and colorimeter can be used to measure the luminance and
chromaticity of the DUT under the standard set-up conditions as shown in Figure 2a). The
LMD shall be aligned perpendicularly to the centre of the DUT. A digital video signal
generator is used to input the signal to be measured.
b) Input signal to the DUT:
1) For the measurement, primary and secondary colours, that is, R, G, B, C, M, Y colour
input signals are used. The signal level for each colour pattern is 255 for an 8-bit input
signal.
2) A 4 % sized single window pattern as shown in Figure 7 is used to measure the
luminance and CIE chromaticity coordinates. The signal level for background is zero.

– 18 – IEC 62341-6-3:2017 © IEC 2017
1/5 H
IEC
Figure 7 – 4 % window pattern for measuring the ‘red’ primary colour
IEC
Figure 8 – 4 % window pattern for each G, B, C, M, Y colour
5.1.2.4.3 Measurement method
For this measurement, the method shall be as follows:
1) Set the input signal to a maximum level for the red primary colour (R = 255).
2) Measure the luminance and CIE 1931 chromaticity value (CIE xyY) of the colour pattern
and record the values.
3) Repeat 1), 2) for all primary and secondary colours G, B, C, M, and Y as shown in Figure 8.
4) A 4 % ‘white’ window is also displayed and measured for reference white tri-stimulus
values X , Y , and Z .
n n n
5) All measured luminance and chromaticity values are used to convert to colour difference
metrics for evaluation of the colour fidelity of the display.
6) Calculate using the following formulae.
• The measurement data for the primary and secondary colour shall be transformed into
the CIELAB colour coordinate as follows:
*
L = 116 × f(Y /Y )−16 (11)
n
*
a = 500 × [ f(X / X )− f(Y /Y )] (12)
n n
*
b = 200 × [ f(Y /Y )− f(Z / Z )] (13)
n n
where
 
 
1/ 3
 
t                 t> 
 29 
 
f (t)=
 
1 29 16
   
  t+       otherwise
 
3 6 116
 
 
1/5 V
• The difference between two stimuli shall be quantified with the following colour
difference formula:
2 2 2
* * * *
∆E = (∆L) +(∆a) +(∆b) (14)
ab
* * * * * *
where ΔL , Δa , and Δb are differences in L , a , and b values between the
measured and the reference colour.
The conversion from CIE L*a*b* to chroma C* and hue-angle h of L*C*h colour
ab
space is given by:
2 2
* * *
C = (a)+(b) (15)
*
 
b
−1
 
h= tan  [degree] (16)
*
 
a
 
• The hue difference metric is calculated by the following rectangular hue difference,
△H*ab:
2 2 2
* * * *
ΔH = (ΔE ) −(ΔL) −(ΔC) (17)
ab ab
* * * * * *
where ΔL = L − L , ΔC = C − C
measured reference measured reference
• The reference colour values, for example, ‘red’, ‘green’, ‘blue’, ‘cyan’, ‘magenta’, and
‘yellow’ values from ITU BT.709, can be chosen by the user of this document.
The colour fidelity of a display can be evaluated by hue difference.
5.1.2.4.4 Reporting
The calculation result using the hue difference metric for the primary and secondary colours
shall be noted in the measurement report.
The measurement results shall include the following items:
a) values of target L*C*h
ab
b) measured values of L*C*h
ab
c) calculation results of ∆H*
ab
Table 3 shows an example of the results.

– 20 – IEC 62341-6-3:2017 © IEC 2017
Table 3 – Example of measurement results for colour fidelity
Colour Reference L*C*h (ITU Measured L*C*h ∆H*
ab ab ab
BT.709)
(53,23, 104.,58, 0.0) (51,66, 107,43, 4,5)
R 0,150
(87,74, 119,78, 96.0) (89,71, 123,43, 92,1)
G 0,225
(32,30, 134,81, 266,3) (30,24, 138,56, 260,8)
B 0,204
(91,12, 50,11, 156,4) (93,76, 48,92, 159,15)
C 1,112
(60,32, 116,36, 288,2) (65,84, 112,85, 283,9)
M 0,594
(97,14, 96,92, 62,8) (98,95, 95,34, 65,7)
Y 3,421
5.1.2.5 Measurement of gamut change of the grey and colour scales
This measurem
...