IEC 62629-62-12:2025

IEC 62629-62-12 ®
Edition 1.0 2025-06
INTERNATIONAL
STANDARD
3D displays –
Part 62-12: Measurement methods for virtual-image type – Image quality
ICS 31.120; 31.260 ISBN 978-2-8327-0391-5
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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 Light measuring device (LMD) . 8
5 Measurement method of uniform-illuminated-flat-background effect on 3D virtual
image . 8
5.1 General . 8
5.2 Measurement configuration of uniform-illuminated-flat-background effect on
3D virtual image . 8
5.3 Illumination for uniform-illuminated-flat-background conditions . 10
5.4 Measurement of contrast and chromaticity of a 3D virtual image against
different uniform-illuminated-flat-backgrounds . 11
5.4.1 General . 11
5.4.2 Conditions . 11
5.4.3 Procedures . 13
5.4.4 Reports . 15
6 Measurement method for ghost image . 16
6.1 Measuring configuration for position estimation . 16
6.2 Conditions. 17
6.3 Procedures . 18
6.4 Reports . 19
7 Measurement methods for binocular misalignment . 19
7.1 General . 19
7.2 Conditions. 20
7.3 Procedures . 22
7.4 Reports . 24
Annex A (informative) Measurement examples . 25
A.1 Measurement example for ghost image . 25
A.2 Measurement example for binocular misalignment . 26
Bibliography . 28

Figure 1 – Measuring configuration for evaluating uniform-illuminated-flat-background
effect on image quality property of a 3D virtual image . 9
Figure 2 – Points for non-uniformity measurement on uniform-illuminated-flat-
background . 10
Figure 3 – Test images for measuring contrast and chromaticity properties affected by
uniform-illuminated-flat-background change on 3D virtual image . 12
Figure 4 – Measuring condition for contrast and chromaticity properties of 3D virtual
image against different uniform-illuminated-flat-background conditions . 13
Figure 5 – Measuring setup for ghost image . 17
Figure 6 – Measurement of ghost image . 18
Figure 7 – Test pattern and measuring configuration for evaluating binocular
misalignment . 21
Figure 8 – LMD positions for evaluating the binocular misalignment . 22

Figure A.1 – Example of test image with ghost phenomenon . 25
Figure A.2 – Example of captured test-image by imaging LMD for binocular
misalignment . 26

Table 1 – Example of measurement results for luminance and chromaticity values in
different uniform-illuminated-flat-background conditions . 16
Table 2 – LMD positions in xyz coordinates or nine measurements . 22
Table 3 – Example of measurement results for horizontal and vertical binocular
misalignment in degrees . 24
Table A.1 – Example of measurement and calculation results for ghost image . 25
Table A.2 – Example of LMD positions in xyz coordinates or nine measurements . 27
Table A.3 – Example of measurement and calculation results for horizontal and vertical
binocular misalignment in degrees . 27

– 4 – IEC 62629-62-12:2025 © IEC 2025
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
3D DISPLAYS –
Part 62-12: Measurement methods for virtual-image type – Image quality

FOREWORD
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IEC 62629-62-12 has been prepared by IEC technical committee 110: Electronic displays. It is
an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
110/1736/FDIS 110/1759/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 62629 series, published under the general title 3D display devices,
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 webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
– 6 – IEC 62629-62-12:2025 © IEC 2025
3D DISPLAYS –
Part 62-12: Measurement methods for virtual-image type – Image quality

1 Scope
This part of IEC 62629 specifies the standard measuring conditions and measurement methods
for determining image quality for 3D displays that produce virtual images, such as 3D heads-up
displays in which the 3D visual information is superimposed with the outside world. Eyewear
displays are however beyond the scope of this document.
The scope of this document does not intend to include eyewear displays considering the
difference between a head-up display and an eyewear display in the aspect of eye box size and
field of view. The eye-tracking function is disabled in the image quality measurement of this
document.
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 62629-1-2, 3D display devices – Part 1-2: Generic – Terminology and letter symbols
IEC 62629-62-11:2022, 3D display devices – Part 62-11: Measurement methods for virtual-
image type – Optical
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62629-1-2 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1.1
virtual image distance
distance from the centre between both eyes to the centre of the virtual image plane
Note 1 to entry: The centre of both eyes corresponds to the point where the half of the binocular spacing is located.
The virtual image plane is the zero parallax plane.

3.1.2
field of view
FOV
angle subtending the area of the virtual image as observed from the centre between both eyes
Note 1 to entry: The FOV is determined by finding the location of the edge point in the test pattern without looking
for the edge in IEC 62629-62-11. However, if the edge of the 3D virtual image is unclear, the edge for field of view
measurement is assumed to be less than 50 % of the center luminance value that is measured at the center position
of the virtual image plane.
Note 2 to entry: The FOV is also determined based on the resolution (e.g. Michelson contrast). Since the edges
obtained by these two criteria could be different, the luminance and resolution-based edges can be obtained.
3.1.3
eye box
<3D display – virtual image type> three-dimensional space within which the users place their
both eyes and properly see the FOV
Note 1 to entry: The eye box size and field of view are quite different between eyewear displays (less than a
few centimetres and about 100 degrees) and HUDs (head-up display) (tens of centimetres and about 10 degrees to
20 degrees). A displacement by eye rotation is comparable to eye box size for eyewear displays whereas this is
much smaller for HUDs. As a result, the effect of selection of rotation point of LMD is noticeable for eyewear displays
but that is negligible for HUDs.
Note 2 to entry: The edge of the eye box is determined based on the resolution (Michelson contrast) or the luminance.
Since the edges obtained by these two criteria could be different, the luminance and resolution-based edges can be
obtained.
3.1.4
binocular misalignment
unintended differences in vertical and horizontal positions observed by the left and right eyes
for a 3D virtual object
Note 1 to entry: It is generally assumed that 3D virtual images reproduced using zero binocular disparity information
is displayed at the same location when observed with the left and right eyes, however, the position difference of 3D
virtual images occurs due to factors such as manufacturing and design errors of HUD optical system.
3.1.5
ghost image
unintended lower intensity duplication of an intended virtual image
Note 1 to entry: The term ‘ghost image’ is commonly used in automotive HUDs. It is extremely rare for multiple
layers of ghost images to be observed in fact. The ghost image can be expressed as ‘secondary image’. The
measurement method introduced in this document corresponds to the case where the secondary image is observed.
3.1.6
designed eye to combiner distance
distance between the half mirror and a viewer that is considered at the design stage of a three-
dimensional display producing three-dimensional virtual images such as three-dimensional
HUD
3.2 Abbreviated terms
HUD head-up display
IPD inter pupillary distance
LMD light measuring device
– 8 – IEC 62629-62-12:2025 © IEC 2025
4 Light measuring device (LMD)
A spectroradiometer-type spot LMD is applied to measure the wavelength and intensity of the
light. The wavelength range shall be at least 380 nm to 780 nm and the wavelength accuracy
shall be 0,3 nm or smaller. The spectral bandwidth shall not be larger than 10 nm for broad
spectrum with no sharp peaks and 5 nm for sharp spectral peaks. The effect of the uniform-
illuminated-flat-background which affects virtual image quality can be measured using a
spectroradiometer-type spot LMD.
The measurement of geometric information is required for quantifying the levels of the binocular
misalignment and the ghost image in this document. The geometric property of the 3D virtual
image can be estimated using one imaging LMD with movement. IEC 62629-62-11:2022,
Annex C, provides the geometric calibration process for the imaging LMD. The specification
items of an imaging LMD that shall be reported are FOV, angular resolution, f number, and the
information related with stray light due to lens itself such as f23, f24, and f25 [1] . The
appropriate aperture size shall be as given in IEC 62629-62-11:2022, 4.1.
5 Measurement method of uniform-illuminated-flat-background effect on 3D
virtual image
5.1 General
The virtual images of numbers, letters, or any other symbols in different depth conditions can
be reproduced by the virtual image type 3D display such as 3D HUD. The 3D virtual images are
expected to be viewed against real-world environment that is very diverse from indoor to outdoor
(i.e. mixed illuminations with different illuminance level and correlated colour temperature).
There is however a limit to implement such diverse environment. A measurement method is
therefore proposed to evaluate the effect of the uniform-illuminated-flat-background change on
the virtual image quality in Clause 5. The size of the uniform-illuminated-flat-background shall
be larger than the FOV of the DUT (for example 3D HUD under test).
The contrast and chromaticity are selected to be measured for 3D virtual images overlapping
with the uniform-illuminated-flat-background. The brightness of the uniform-illuminated-flat-
background is varied by adjusting the illuminance level of the lighting in front of the white
diffuser, and the size of the white diffuser is determined to be greater than the FOV of the virtual
image plane, as illustrated in Figure 1. The example of illuminance level and correlated colour
temperature of the illumination to form uniform-illuminated-flat-background conditions are given
in 5.3.
5.2 Measurement configuration of uniform-illuminated-flat-background effect on 3D
virtual image
Figure 1 shows the geometric relationship consisting of an eye box, a virtual image plane, and
a white diffuser. If a user’s eyes are placed in the eye box, it is assumed that the user can view
the entire virtual image with natural rolling movement of the eyes. The eye box position can be
specified by a supplier otherwise this can be estimated in accordance with the method given in
IEC 62629-62-11:2022 (specifically in 4.2.3). A 3D coordinate system of the x, y and z axes
indicated in Figure 1 is defined in order to determine the positions of the 3D image and the
virtual image plane from the eye box.
___________
Numbers in square brackets refer to the Bibliography.

H V
NOTE The subscripts L, C, R (in LMD LMD and LMD ) represent the position of spot LMD θ and θ : the
,
FOV FOV
L C R
horizontal and vertical FOV of the virtual image plane.
Figure 1 – Measuring configuration for evaluating uniform-illuminated-flat-background
effect on image quality property of a 3D virtual image
The centre of the eye box is defined to be the origin (x = 0, y = 0 and z = 0) at which the entrance
pupil position of the LMD is placed. The positions of the LMD and the LMD are placed on
C L R
the left and right sides at the same distance interval from the LMD . For example, assuming a
C
binocular distance of 64 mm, the LMD and the LMD are located on the left and right sides
L R
32 mm away from LMD . A designed eye to combiner distance shown in Figure 1 should be
C
suggested by a supplier. A part of the light rays is reflected from the half mirror and the rest of
the light rays is transmitted through the half mirror for the 3D displays producing 3D virtual
images. Therefore, the distance between the half mirror and a viewer is considered at the design
stage of a 3D display.
The room where the measurement is performed is a darkroom. If the eye is located inside the
eye box, the entire FOV of the virtual image plane can be observed, so the white diffuser screen
size shall be large enough to overlap the entire virtual image plane at any position inside the
eye box. However, Figure 1 shows that the size of the white diffuser shall be larger than the
viewing angle of the virtual image plane at the LMD position as an example. The minimum and
C
maximum size of the white diffuser, which is placed at the virtual image distance (D ) in
VI
H V
Figure 1, shall be determined using the horizontal and vertical FOV (θ and θ ) of the
FOV FOV
virtual image plane by Formulae (1) and (2).
If the virtual image distance (D ) is 7 m and the horizontal FOV (θ) is 10°, the background width
VI
shall be greater than 1,224 8 m and smaller than 1,471 5 m. If the virtual image distance (D )
VI
is 7 m and the vertical FOV (θ′) is 6°, the background height shall be greater than 0,733 7 m
and smaller than 0,880 8 m.
– 10 – IEC 62629-62-12:2025 © IEC 2025
(1)
θ θ×1,2
2××D tan < WD< 2×× tan
VI B VI 

(2)
′′
θθ ×1,2
2××D tan < HD< 2×× tan
VI B VI  
 
where
W is the background (white diffuser) width;
B
H is the background (white diffuser) height;
B
θ is the horizontal FOV of the imaging LMD;
θ′ is the vertical FOV of the imaging LMD; and
D is the virtual image distance in millimetres (mm) between (0, 0, 0) in the eye box and
VI
the centre of the virtual image plane. The measurement method of D is described in
VI
IEC 62629-62-11.
Figure 2 – Points for non-uniformity measurement
on uniform-illuminated-flat-background
5.3 Illumination for uniform-illuminated-flat-background conditions
The uniform-illuminated-flat-background condition is very much diverse in real world. It is
therefore recommended to measure at the same time (A) the contrast and colour of the virtual
image, and (B) the luminance and correlated colour temperature of the corresponding
background where the virtual image is observed. It is however very difficult to measure the
simultaneous changes of (A) and (B) in reality because there is a limit to implementing various
uniform-illuminated-flat-background conditions. It is therefore intended to provide
representative illumination to create uniform-illuminated-flat-background conditions as an
example in 5.3, considering that HUD manufacturers also set the brightness of the HUD to
automatically adjust according to the brightness of external environments.
The illumination to create uniform-illuminated-flat-background conditions can be selected from
the following examples if a supplier does not specify them. The illuminance level and correlated
colour temperature are selected in reference to IEC 62977-2-2 for indoor [2], and ISO 15008
for outdoor [3]. For spectral measurement of the uniform-illuminated-flat-background condition,
spectrally smooth broadband light source (such as approximation to CIE Standard Illuminant A)
should be used.
– Dark condition: the illuminance value of the white diffuser in Figure 1 should be less than
0,01 lx.
– Indoor condition: the illuminance value of the white diffuser in Figure 1 should be
200 – 300 lx and the correlated colour temperature should be close to CIE Standard
Illuminant A or D50 or D65.
– (Outdoor) night condition: the illuminance value of the white diffuser in Figure 1 should not
exceed 10 lx, with a relative tolerance of ± 5 % and the correlated colour temperature should
be close to CIE Standard Illuminant.
– (Outdoor) twilight condition: the illuminance value of the white diffuser in Figure 1 should be
250 lx, with a relative tolerance of ± 5 % and the correlated colour temperature should be
close to CIE Standard Illuminant A.
– (Outdoor) day condition with diffuse ambient light: the illuminance value of the white diffuser
in Figure 1 should be 5 000 lx, with a relative tolerance of ± 5 % and the correlated colour
temperature should be close to CIE Standard Illuminant D65 or CIE Illuminant D75.
The background conditions can be categorized based on the absolute illuminance value as
described above. The illuminance value is measured to evaluate the uniformity of the
background against nine points (BG to BG in Figure 2). The correlated colour temperature of
0 8
the uniform-illuminated-flat-background condition is measured using a spot LMD (LMD ) at the
C
centre point of the white diffuser (BG in Figure 2). As for the non-uniformity of the uniform-
illuminated-flat-background, the illuminance values at nine points (BG to BG ) of the white
0 8
diffuser, as shown in Figure 2, shall fall within the ± 10 % error range compared to the target
value. For example, if the target value is 5 000 lx, the illuminance value at nine points shall be
set up to be within 5 000 ± 50 lx. To create uniform-illuminated-flat-background condition, a
uniform illuminated sphere or a uniformly backlight behind the screen can be used as long as
this uniformity requirement meets instead of the white diffuser screen with illumination in
Figure 1.
5.4 Measurement of contrast and chromaticity of a 3D virtual image against different
uniform-illuminated-flat-backgrounds
5.4.1 General
If a uniform-illuminated-flat-background is not dark condition in 5.3, the effect of stray light shall
be measured and eliminated. There is a limit to implementing all environments where 3D virtual
images are viewed (see 5.1), so the measurement method using flat background is described.
The measurement procedure for the stray light caused by the limited-size background is given
in 5.4.3.1. The measurement procedure for the effect of the change in the uniform-illuminated-
flat-background on luminance, contrast and chromaticity is given in 5.4.3.2.
NOTE A measurement exposes the LMD to stray light if the light sources, which are to produce the different
background conditions in Figure 4, reflect off the white diffuser and non-black objects in the measurement room. Due
to the complex environment such as the presence of a 3D HUD optical system and a half mirror, etc., there is a limit
to the complete removal of the strain light.
5.4.2 Conditions
The following detailed conditions shall be applied:
a) display setting: if there are internal setting conditions that vary depending on the brightness
of the actual environment, the two internal display setting conditions with the darkest and
brightest luminance output are selected and evaluated alternately;
NOTE 1 If the display has a function to adjust chromaticity points by background colour variation, the
measurement will be conducted after deactivating this function.
b) test pattern: the test image with the centre square (P ) and the grey background having 128
c
of the 8-bit digitized RGB values in Figure 3(a);
NOTE 2 This test pattern having grey background is prone to veiling glare errors when measuring black centre
square.
– 12 – IEC 62629-62-12:2025 © IEC 2025
c) test si
...