IEC 62906-5-1:2021

IEC 62906-5-1 ®
Edition 1.0 2021-11
INTERNATIONAL
STANDARD
colour
inside
Laser displays –
Part 5-1: Measurement of optical performance for laser front projection
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IEC 62906-5-1 ®
Edition 1.0 2021-11
INTERNATIONAL
STANDARD
colour
inside
Laser displays –
Part 5-1: Measurement of optical performance for laser front projection

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.260 ISBN 978-2-8322-1049-5

– 2 – IEC 62906-5-1:2021 © IEC 2021
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms, definitions and abbreviated terms . 7
3.1 Terms and definitions . 7
3.2 Abbreviated terms . 8
4 Standard measuring conditions . 8
4.1 General . 8
4.2 Standard measuring environmental conditions . 9
4.3 Standard dark room conditions. 9
4.4 Standard conditions of measuring equipment . 9
4.5 Conditions of measuring equipment . 10
4.5.1 General conditions . 10
4.5.2 Measurement coordinate system . 13
4.5.3 Diffuse reflectance standard . 13
4.5.4 Illuminance meter . 14
4.5.5 Colorimeter . 14
4.5.6 Signal source of test patterns . 14
4.5.7 Integrating sphere . 14
4.5.8 Spectral radiance/irradiance meters. 15
5 Adjustment of the laser projector . 15
5.1 Projector and image plane placement . 15
5.2 Focusing of the projector . 15
5.3 Standard projector setup conditions . 16
5.4 Standard image measurement locations . 16
5.5 Colour tile patterns . 17
5.6 RGBCMY colour pattern . 18
5.7 Measuring the projected image area . 19
5.8 Maintaining the normal working conditions . 20
6 Measuring methods . 20
6.1 Light output . 20
6.2 Spectroradiometric measurements . 20
6.2.1 General . 20
6.2.2 Measuring equipment . 20
6.2.3 Measuring method . 20
6.2.4 Data analysis . 21
6.3 Illuminance uniformity . 21
6.3.1 General . 21
6.3.2 Measuring equipment . 21
6.3.3 Measuring method . 22
6.4 Contrast ratio . 22
6.4.1 General . 22
6.4.2 Measuring equipment . 22
6.4.3 Measuring method . 22
6.5 Chromaticity coordinates . 23
6.5.1 General . 23

6.5.2 Measuring equipment . 23
6.5.3 Measuring method . 23
6.5.4 Data analysis . 24
6.6 White point chromaticity coordinates and correlated colour temperature . 24
6.6.1 General . 24
6.6.2 Measuring equipment . 24
6.6.3 Measuring method . 25
6.6.4 Data calculation . 25
6.7 Greyscale illuminance and chromaticity coordinates . 25
6.7.1 General . 25
6.7.2 Measuring equipment . 25
6.7.3 Measuring method . 25
6.8 Colour uniformity . 26
6.8.1 General . 26
6.8.2 Measuring equipment . 26
6.8.3 Measuring method . 26
6.8.4 Data analysis . 27
6.9 Colour gamut . 27
6.9.1 General . 27
6.9.2 Chromaticity gamut area . 28
6.9.3 CIELAB gamut volume . 30
Annex A (normative) RGB boundary colours for CIELAB gamut volume measurements . 33
A.1 General . 33
A.2 Equally spaced 98 boundary colours on the RGB cube . 33
A.3 Recommended 602 boundary colours on the RGB cube . 36
Annex B (informative) Calculation method for CIELAB gamut volume. 51
B.1 Purpose . 51
B.2 Procedure for calculating the colour gamut volume . 51
B.3 Number of sampled colours . 52
B.4 RGB cube surface subdivision method for CIELAB gamut volume calculation . 52
B.4.1 General . 52
B.4.2 Assumption . 52
B.4.3 Uniform RGB grid algorithm . 53
B.4.4 Software example execution . 55
Annex C (informative) Calculation method for chromaticity gamut area overlap . 63
C.1 Purpose . 63
C.2 Chromaticity gamut area overlap . 63
Annex D (informative) Light output . 64
D.1 White light output (WLO) method . 64
D.1.1 Purpose . 64
D.1.2 Measuring equipment . 64
D.1.3 Measuring method . 64
D.1.4 Data calculation . 64
D.2 Colour-signal white (CSW) method . 65
D.2.1 Purpose . 65
D.2.2 Measuring equipment . 65
D.2.3 Measuring method . 65
D.2.4 Data calculation . 66

– 4 – IEC 62906-5-1:2021 © IEC 2021
Bibliography . 67

Figure 1 – Virtual screen setup with (a) the illuminance LMD or (b) reflectance
standard placed at the projector image plane for standard measurements . 12
Figure 2 – Polar coordinate system used to describe the inclination and azimuthal

angle of the projector . 13
Figure 3 – Example image pattern with width H and height V used to focus the
projector . 16
Figure 4 – Standard measuring locations on the projected image . 17
Figure 5 – Set of four colour tile test patterns used for projector characterization . 18
Figure 6 – Standard medium APL RGBCMY test pattern used for centre illuminance
and colour measurements with 25 % APL . 19
Figure 7 – Area of projected image . 20
Figure 8 – Example representation of the chromaticity gamut area in the CIE 1931
chromaticity diagrams . 29
Figure 9 – Example of range in colours produced by a given display as represented by
the CIELAB colour space . 32
Figure B.1 – Analysis flowchart for calculating the CIELAB gamut volume . 52
Figure B.2 – Example of tessellation using a 5 × 5 grid of surface colours on the RGB
cube . 54
Figure B.3 – Example of tessellation for the RGB cube using a 3 × 3 grid . 56
Figure B.4 – Example of tessellation for the CIELAB gamut volume using a 3 × 3 grid . 57
Figure C.1 – Example of CIE 1931 chromaticity gamut area overlap between the

measured and reference colour gamut . 63

Table 1 – Recommended format for greyscale results . 26
Table 2 – Example of colour uniformity analysis . 27
Table 3 – Equivalent 8-bit RGB input signals used for colour gamut area
measurements . 28
Table 4 – Example of report format for CIELAB gamut volume . 32
Table A.1 – Equally spaced 98 RGB boundary colours used for CIELAB gamut volume
measurements . 33
Table A.2 – Recommended RGB boundary colours used for CIELAB colour gamut

volume measurements . 36
Table B.1 – Example data format used for CIELAB colour gamut volume
measurements . 56

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LASER DISPLAYS –
Part 5-1: Measurement of optical performance for laser front projection

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
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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.
IEC 62906-5-1 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
110/1351/FDIS 110/1367/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/standardsdev/publications.

– 6 – IEC 62906-5-1:2021 © IEC 2021
A list of all parts in the IEC 62906 series, published under the general title Laser displays, can
be found on the IEC website.
Future documents in this series will carry the new general title as cited above. Titles of existing
documents 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 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.

LASER DISPLAYS –
Part 5-1: Measurement of optical performance for laser front projection

1 Scope
This part of IEC 62906 specifies the standard measurement conditions and measurement
methods for front projection displays without screen which use lasers or laser hybrids as light
sources. The hybrid light sources can use both lasers and spontaneous emission-based light
sources. This document covers optical performance measurements for full-frame projection
technologies such as digital micro-mirror devices (DMDs), liquid crystal on silicon (LCOS), and
liquid crystal display (LCD) projectors. Other displays, such as raster-scanned (flying spot)
projection displays, are not included.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
shall constitute 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 60825-1, Safety of laser products – Part 1: Equipment classification and requirements
IEC 61947-1:2002, Electronic projection – Measurement and documentation of key
performance criteria – Part 1: Fixed resolution projectors
IEC 62471-5, Photobiological safety of lamps and lamp systems- Part 5: Image projectors
IEC TR 62977-2-3, Electronic display devices – Part 2-3: Measurements of optical properties –
Multi-colour test patterns
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 168-2005, Criteria for the evaluation of extended-gamut colour encoding
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions 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

– 8 – IEC 62906-5-1:2021 © IEC 2021
NOTE Most definitions and units are in accordance with the naming methods used in ISO 11145 and IEC 62906-1-2
3.1.1
chromaticity difference
geometric distance Δu′v′ between two colours in the CIE 1976 u’v’ chromaticity diagram
3.1.2
white light output (WLO) method
method that estimates total luminous flux measured from the average of nine points for a full
white screen or for a sequence of white tiles that total the area of the full screen
3.1.3
colour-signal white (CSW) method
method that estimates total luminous flux from the sum of the input-referred red, green, and
blue tile sequence
Note 1 to entry: The area of all colour tiles totals the area of the full screen.
3.2 Abbreviated terms
APL average picture level
CAT chromatic adaptation transform
CCT correlated colour temperature
CGV colour gamut volume
CIE International Commission on Illumination
CIELAB CIE 1976 (L*a*b*) colour space
CSW colour signal white
CT colour tile
DMD digital micro-mirror device
DUT device under test
EOTF electro-optical transfer function
ISO International Organization for Standardization
LCD liquid crystal display
LCOS liquid crystal on silicon
LDD laser display device
LED light emitting diode
LMD light measuring device
RGB red, green, blue
RGBCMY red, green, blue, cyan, magenta, yellow
SDR standard dynamic range
sRGB standard RGB colour space as defined in IEC 61966-2-1
WLO white light output
4 Standard measuring conditions
4.1 General
Unless stated otherwise, the following standard measuring conditions shall be used. When
carrying out optical measurements of the laser projector, the measuring environment,
equipment, and methods shall comply with IEC 60825-1 and IEC 62471-5 for human safety.

4.2 Standard measuring environmental conditions
All the tests and measurements shall be made under the following standard environmental
conditions:
– temperature: 25 ºC ± 3 ºC
– relative humidity: 25 % to 85 %
– pressure: 86 kPa to 106 kPa
If other conditions are used, they shall be noted in the report.
NOTE For temperature sensitive cases, 25 ºC ± 2 ºC is used.
4.3 Standard dark room conditions
The laser projectors are intended to be measured under dark room conditions. The illuminance
contribution from unwanted background illumination shall be less than 1 / 20 of the projector’s
lowest illuminance in a given test pattern. The room background illuminance can be estimated
by using a projection mask (see section 15.1.4 in [1] ). For the determination of the colorimetric
values, the background tri-stimuli shall be applied.
When it is not possible to achieve the background illuminance conditions, then background
subtraction by using the projection mask for the same test pattern shall be used in the
measurement. If the luminance measurement with a reflectance standard is applied to
determine the illuminance, the dimension of the projection mask has to take into account the
measurement area of the reflectance standard instead of the measurement area of the
illuminance meter.
In the case of direct illuminance measurement, a stray light elimination tube (see section 15.1.5
in [1]) can be used with the illuminance meters to minimize the contribution of the background
illumination. A stray light elimination tube is required if for a given test pattern, the background
illuminance measured with a projection mask is more than 67 % of the illuminance measured
on the same location in the test pattern without the projection mask.
It should be noted that the reflections from the mask, projector shell, LMD and their frames in
the front of the detection area can produce significant background illuminance, especially in the
case of a luminance measurement. It is recommended to absorb the direct projection beam by
applying light traps behind the virtual screen. Blackout curtains and black room surface (such
as walls, ceiling, floor, etc.) with a reflectance less than 3 % are valuable for reducing the
background illumination.
4.4 Standard conditions of measuring equipment
Standard equipment conditions are described in 4.5. Any deviations from these conditions shall
be noted in the report.
Measurements shall be started after the laser projector, the light source, and measuring
instruments achieve stability. The illuminance originating from the projector shall not vary by
more than ±2 % over the entire measurement duration.
___________
1 Numbers in square brackets refer to the Bibliography.

– 10 – IEC 62906-5-1:2021 © IEC 2021
4.5 Conditions of measuring equipment
4.5.1 General conditions
The measuring equipment shall be as follows:
a) The laser projector is to be characterized by focusing a test pattern on a projected image
plane at a defined distance from the projector. This image plane is the location where a
projection screen would be placed. The image plane for projector measurements shall be
set up in accordance with the angle, height, and distance specified in the manufacturer’s
set-up instructions (Figure 1). The projector’s optical axis shall lie in the vertical plane
perpendicular to the image plane and intersect the centre of the screen. The measurement
configuration shall be reported.
b) Unless stated otherwise, the measurement area of the LMD shall be at the centre of the
image area to be measured.
c) The measurement area at the image plane shall be at least 1 cm in diameter and contain at
least 10 pixels × 10 pixels. It shall be confirmed that this number of pixels is sufficient by
shifting the LMD over a lateral distance of 20 % of the measurement area diameter and by
verifying that the illuminance changes by less than 2 % and the colour by less than 0,003 in
(x, y) chromaticity values, for a full white screen as test pattern. A large enough
measurement area is needed to average out speckle-induced non-uniformity.
d) Illuminance shall be determined by using direct illuminance measurement with an
illuminance (or spectral irradiance) meter with a cosine-corrected transmission diffuser or
an integrating sphere as LMD (Figure 1a), or the measurement be made using a reflectance
standard and a luminance (or spectral radiance) meter as LMD (Figure 1b). The optical
properties of these devices are generally dependent on the inclination angle of the light.
The measurements shall compensate for any light incidence angle dependence of these
items. This is especially important for short-focus (short-throw) projectors where the
inclination angle can be large. In that case, the integrating sphere with a thin edge at the
entrance port is preferred. Both the integrating sphere and reflectance standard method can
be used but they will need to be calibrated for the illumination inclination angle used in the
measurement. The image plane can be established through use of a virtual screen where
the image is focused in the x–y coordinate plane. The virtual screen can be set up with the
LMD (Figure 1a) or reflectance standard (Figure 1b). The front surface of the diffuser or
reflectance standard, or the entrance port of the integrating sphere should be placed at the
projector image plane. The measurement area shall lie within the plane of this virtual screen.
The screen can be constructed with a black frame, with millimetre grids placed at the corners
of the frame. The frame shall be sufficiently large so that the specified image area is
contained within the four corner grids. The spacing between the corner grids shall be
calibrated to an accuracy of ±0,2 % of the minimum vertical or horizontal dimension of the
projected image. The millimetre grids need to be covered with matte black materials to avoid
causing stray light when performing sensitive dark level measurements.
e) Spectrally integrated light measurements shall be measured in terms of calibrated
photometric or colorimetric units traceable to a recognized national metrology institute,
illuminance for an illuminance meter, or CIE 1931 tristimulus values (X, Y, Z) and
chromaticity coordinates (x, y) for a colorimeter.
f) Photometric and colorimetric data shall be calculated for a CIE 2º standard colorimetric
observer, as specified in CIE 15.
g) The light measuring device (LMD) shall have enough sensitivity and dynamic range to
perform the required task. The measured LMD signal in the lowest illuminance measurement
shall be at least ten times greater than the dark level (noise floor) of the LMD, and no greater
than 85 % of the saturation level in the highest illuminance measurement. The LMDs are
especially prone to saturation with laser sources, and calibrated neutral density filters are
generally applied. Detector saturation can be diagnosed by using a calibrated neutral
density filter in front of the projector.

h) If the laser projector light is polarized, the polarization dependence of the LMD shall be less
than 1 %.
i) The relative uncertainty and repeatability of all the measuring devices shall be maintained
by following the instrument supplier’s recommended calibration schedule.
j) If temporal synchronization with the projector or video source is possible, the LMD shall be
synchronized with the frame synchronization signal, and the LMD integration time shall be
an integer number of frame periods. If synchronization is not possible, the LMD integration
time shall be larger than two hundred frame periods.

– 12 – IEC 62906-5-1:2021 © IEC 2021

a) Virtual screen setup with the illuminance LMD

b) Virtual screen setup with the reflectance standard and luminance meter

Figure 1 – Virtual screen setup with (a) the illuminance LMD or (b) reflectance standard
placed at the projector image plane for standard measurements

4.5.2 Measurement coordinate system
The measurement angular positioning is referred to by the coordinate system illustrated in
Figure 2. The projected image is focused on the x-y plane of the coordinate system. The
projector’s optical axis can be described by two angles. The inclination angle θ increases
relative to the surface normal of the image plane (z-axis). The angle of rotation, or azimuthal
angle φ, increases from the x-axis in the x-y plane. This corresponds to the counter clockwise
rotation of a clock dial, where φ = 0º when the dial is at 3 o’clock and φ = 90º when the dial is
at 12 o’clock.
Figure 2 – Polar coordinate system used to describe the inclination
and azimuthal angle of the projector
4.5.3 Diffuse reflectance standard
The illuminance or spectral irradiance can be measured directly, or by measuring the luminance
or spectral radiance from a diffuse reflectance standard placed at the desired location in the
image plane. Diffuse reflectance standards can be obtained with a diffuse reflectance of 98 %
or more. A luminance L measurement from a spectrally flat diffuse reflectance standard can
std
be used to determine the illuminance E,
πL
std
E =
(1)
R
std
where
R is the calibrated luminous reflectance factor for that measurement configuration. The
std
calibration of R shall be traceable to a national metrology institute.
std
The spectral irradiance E(λ) can follow the same form as Formula (1), where L then denotes
std
the spectral radiance L (λ) and where R denotes the calibrated spectral reflectance factor
std std
R (λ), which will have to be known and available in the visible wavelength range.
std
The white reflectance standard shall be calibrated for the same illumination and detection
geometry as will be used in the measurement.

– 14 – IEC 62906-5-1:2021 © IEC 2021
The LMD is generally positioned normal to the surface of the reflectance standard. If the
projector placement interferes with this LMD position, then the LMD can be inclined away from
the projector, but it shall still be aligned as close as possible to the normal axis of the reflectance
standard. The value of R (or R (λ)) under this inclination angle shall not change more than
std std
0,2 % from its value at normal incidence. If the variation is unacceptable, the correction factor
shall be applied in this condition.
NOTE A white reflectance standard that is calibrated for spectral reflectance is preferred. If the white reflectance
standard is calibrated for its photometric properties (i.e. luminous reflectance factor), then the white reflectance
standard will only give valid results for light sources with the same relative spectral distribution that was used in the
calibration.
4.5.4 Illuminance meter
Filtered illuminance meters are generally considered not to be accurate enough for laser
projector measurements and are not recommended. Spectral measurement instruments are
preferred for these narrow bandwidth light sources. If the filtered illuminance meter does not
meet the required accuracy, it shall be calibrated with a spectral irradiance meter. However, it
is noted that this calibration is valid only for a given spectral distribution of the light source (e.g.
red, green, blue primaries, in addition to white and black), and the illuminance meter will need
a unique calibration factor for every different spectral distribution. Several methods for
performing a relative calibration of the illuminance meter are available in the literature [3], [4].
Many illuminance meters employ diffusers as a means to capture the incident illumination.
These tend to also be valuable in scrambling projector polarization and smoothing speckle non-
uniformity. If a light scrambling element (like a diffuser) is not employed in the illuminance meter,
then its insensitivity to polarization and speckle shall be confirmed with a spectral irradiance
meter that uses a diffusing element.
4.5.5 Colorimeter
Filtered colorimeters are generally not accurate enough for laser projector measurements, and
are not recommended. Spectral measurement instruments are preferred for these light sources.
If the filtered colorimeter does not meet the required accuracy, it shall be calibrated with a
spectral irradiance meter. However, it is noted that this calibration is valid only for a given
spectral distribution of the light source (e.g. red, green, blue primaries, in addition to white and
black). Each of these spectral distributions will require its own unique calibration factor. Several
methods for performing a relative calibration of the colorimeter are available in the literature [3],
[4]. The colorimeter shall be insensitive to polarization and speckle non-uniformity. If a
scrambling element (like a diffuser) is not employed in the colorimeter, then its insensitivity to
polarization and speckle shall be confirmed with a spectral irradiance meter or
spectroradiometer that uses a diffusing element.
4.5.6 Signal source of test patterns
If a digital video interface is available, it shall be used to display the test patterns. A video
generator that uses the native resolution of the projector is recommended. If a computer’s digital
video output can also produce the same displayed images, it may also be used for displaying
the required test patterns. If only an analogue video input is available on the projector, a pattern
generator shall be used. The characteristics of this pattern generator are described in
IEC 61947-1:2002, Annex B.
4.5.7 Integrating sphere
An integrating sphere can be used in conjunction with an LMD to measure illuminance and
spectral irradiance. When using integrating spheres, the following guidelines shall be followed:
a) The sphere structure shall be designed with baffles to avoid direct light incident onto the
LMD.
b) The inner surface of the integrating sphere shall be a white diffuse reflecting material with
a spectral reflectance of > 90 % from 380 nm to 780 nm.

c) The light produced by the projector shall not cause the material in the integrating sphere to
fluoresce.
d) When measuring light at large inclination angles (e.g. short-throw projectors), the integrating
sphere shall have a thin edge at the entrance port.
4.5.8 Spectral radiance/irradiance meters
The narrow spectral line widths of the projector laser sources usually require the use of a
spectroradiometer with relatively small spectral bandwidths for accurate results. It is
recommended to use a spectral stray light correction, such as in [23]). A spectroradiometer can
be configured with an integrating sphere or cosine-corrected diffuser to measure the spectral
irradiance of the projector directly. The following requirements are given for these instruments:
a) The spectroradiometer wavelength accuracy shall be within ±0,5 nm. The wavelength
measuring range shall be at least 380 nm to 780 nm.
b) It is recommended to use a spectroradiometer with a spectral bandwidth of ≤ 5 nm
(full-width-at-half-maximum).
c) The CIE 1931 x and y chromaticity accuracy shall be less than ±0,001 5 for a CIE Illuminant
A light source. The illuminance or luminance accuracy shall be less than ±2% for a CIE
Illuminant A light source.
d) The CIE 1931 x and y chromaticity repeatability shall be less than ±0,000 5 for a CIE
Illuminant A light source. The illuminance or luminance repeatability shall be less than
±0,5 % for a CIE Illuminant A light source.
An alternative method of spectral irradiance can be implemented by using a spectral radiance
meter with a diffuse reflectance standard.
If measurements are taken at large incident angles, such as in the case of short-focus projectors,
it is recommended to use the spectral radiance meter with a reflectance standard or integrating
sphere with a thin edge at the entrance port. The reflectance standard shall be corrected for
the large inclination angle dependence.
5 Adjustment of the laser projector
5.1 Projector and image plane placement
The amount of flux exiting the lens of the projector can be affected by the focus and zoom of
the projector lens. The zoom and preferred image size will dictate an optimum distance from
the projector to the image plane where the flux is the greatest. The manufacturer shall specify
the projector angle, height, zoom, image size and optimum distance. A lens-shift projector shall
be positioned at its optimum optical path as specified by the manufacturer. If the manufacturer
does not define the optimum setup, the projector zoom shall be set to the wide-angle position
(largest angle, lowest throw ratio). The projector shall project an image at its native aspect ratio.
The projector and image plane (virtual screen) configuration shall be documente
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