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Background Statement for SEMI Draft Document 5634CNEW STANDARD: TEST METHOD FOR COLOR REPRODUCTION AND PERCEPTUAL CONTRAST OF DISPLAYSNotice: This background statement is not part of the balloted item. It is provided solely to assist the recipient in reaching an informed decision based on the rationale of the activity that preceded the creation of this Document.

Notice: Recipients of this Document are invited to submit, with their comments, notification of any relevant patented technology or copyrighted items of which they are aware and to provide supporting documentation. In this context, “patented technology” is defined as technology for which a patent has issued or has been applied for. In the latter case, only publicly available information on the contents of the patent application is to be provided.

BackgroundAs high quality properties of digital TV like HDTV, 4K UHDTV and 8K UHDTV have been demanded, it is necessary to present the highest image quality with rich and authentic color, subtle gray and color tone and dynamic contrast, and set the suitable and advanced evaluation methods of display quality. The aim of various methods for measuring color gamut, brightness, and contrast based on human perception have been studied is to match the image quality with human eyes. Even though there are conventional measuring methods like luminance, tristimulus values for the objective evaluation method, there are imperfect methods considering a viewing condition, perceptual parameters.

The basic rationale of this document is the color appearance model which is proposed at CIE in 2002. A new method is to calculate a color volume and contrast with color appearance model which is uniform color space with human visual perception.

The 5634 and 5634A went out from 2013 to 2013 period. The last one, 5634B, issued cycle 8, 2014 and failed committee review to reflect technical comments in September, 2016.

Review and Adjudication Information

Task Force Review Committee Adjudication

Group: To be reviewed at the Korea Perceptual Image Quality TF Meeting

Korea FPD Metrology Technical Committee

Date: Feb 10, 2016 Feb 10, 2016Time & Time Zone: 10:00pm – 12:00pm 13:00pm – 14:00pmLocation: SEMI Korea office SEMI Korea officeCity, State/Country: Seoul, Korea Seoul, Korea

Leader(s): Jong Ho Chong (Samsung Display)[email protected]

JongSeo Lee (Samsung Display)[email protected] Il-Ho Kim (LMS)[email protected]

Standards Staff:Natalie Shim (SEMI Korea)[email protected]

Natalie Shim (SEMI Korea)[email protected]

This meeting’s details are subject to change, and additional review sessions may be scheduled if necessary. Contact the task force leaders or Standards staff for confirmation.

Telephone and web information will be distributed to interested parties as the meeting date approaches. If you will not be able to attend these meetings in person, but would like to participate by telephone/web, please contact Standards staff.

Check www.semi.org/standards on calendar of event for the latest meeting schedule.

http://www.semi.org/standards

mailto:[email protected]





DRAFTDocument Number:

Date: 5/18/23

SEMI Draft Document 5634CNEW STANDARD: TEST METHOD FOR COLOR REPRODUCTION AND PERCEPTUAL CONTRAST OF DISPLAY1 Purpose1.1 This standard specifies measurement conditions and methods for describing the visual color quality in 3-dimensional color space, and the perceived contrast with perceptual parameters in color electronic display devices.

1.2 The CIE1 XYZ color space is derived from the experimental results and it has been used to set color performance of displays in CIE xy or u’v’ chromaticity diagram without brightness.

1.3 For measurement, setting test patterns based on Average Picture Level (APL) of IEC2 62087:2011 are required, instead of full screen patterns, which are composed with small size of window box. The full screen patterns are not suitable for emissive displays which of luminance are adjusted with contents.

1.4 The contrast ratio has been widely used although the calculated value is dramatically changed by dark state luminance. This metric does not consider human visual characteristics. Therefore, it is more reliable to consider the perceptual indices.

2 Scope2.1 This standard is applicable to the color electronic display devices, except on the transparent display.

2.2 This standard includes the measurement for physical data, analysis, and calculation methods which have perceptual factors.

2.3 The term “perceptual” is subject to CIECAM02 (CIE Color Appearance Model 2002) in this standard.

NOTICE: SEMI Standards and Safety Guidelines do not purport to address all safety issues associated with their use. It is the responsibility of the users of the Documents to establish appropriate safety and health practices, and determine the applicability of regulatory or other limitations prior to use.

3 Limitation3.1 Measurements are subject to errors or imprecision due to the user, environmental factors, and mis-calibration of measurement system or measurement system limitations.

3.2 Results may vary with ambient illumination conditions or in the presence of uncontrolled stray light reflections.

4 Referenced Standards and Documents4.1 IDMS

4.1.1 Information Display Measurement Standard (IDMS) 1.0

4.2 CIE Standards

4.2.1 CIE 15.3 —Colorimetry

4.2.2 CIE 159 —CIECAM02

4.3 IEC Standards

4.3.1 IEC 62341-6-2 — OLED Displays — Measuring methods of visual quality and ambient performance

4.3.2 IEC 62087- Methods of measurement for the power consumption of audio, video and related equipment.

NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions.

1 Commission Internationale De L'eclairage (International Commission On Illumination), Kegelgasse 27, A-1030 Vienna/AUSTRIA. Telephone: +43.1.714.31.87.0. Fax : +43.1.714.31.87.18 ; http://www.cie.co.at2 International Electrotechnical Commission, 3 rue de Varembé, Case Postale 131, CH-1211 Geneva 20, Switzerland. Telephone: 41.22.919.02.11; Fax: 41.22.919.03.00; http://www.iec.ch

This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline. Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.

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http://www.iec.ch/

http://www.cie.co.at/


Date: 5/18/23

5 Terminology5.1 Abbreviations and Acronyms

5.1.1 APL – average picture level.

5.1.2 FOV – field of view

5.1.3 PCL – perceptual contrast length

5.1.4 VCRC – volume color reproduction capability

5.1.5 LMD – light measurement device

5.1.6 DUT – device under test

5.2 Definitions

5.2.1 brightness – the attribute of a human visual sensation according to which an area appears to emit more or less light

5.2.2 color gamut boundary – the outer surface determined by a color gamut form

5.2.3 perceptual contrast length – the difference of black and white brightness of the screen

5.2.4 volume color reproduction capability – the volume of the perceived color gamut obtained in 3-dimensional color space which is composed of colorfulness, hue and brightness

6 Standard Measurement Condition6.1 Measuring Conditions

6.1.1 Environmental conditions

6.1.1.1 In order to obtain accurate measured data, the following environmental conditions are required.

Temperature: 25±2 °C

Humidity: 25-85 % relative humidity

Pressure: 86-106 kPa

Air flow: no wind

Vibration / Shock: no influence

6.1.2 Ambient conditions

6.1.2.1 Dark room condition

6.1.2.1.1 The luminance contribution from the background illumination shall be less than 0.01 cd/m2.

6.1.2.2 Ambient illuminations

Uniform hemispherical diffuse light source

6.1.3 Measuring equipment conditions

6.1.3.1 In this standard, a LMD such as spectral radiometer, at least from 380 nm to 780 nm wavelength ranges or a filter photometer shall be used.

6.1.3.2 The luminance accuracy of the instrument shall be within ±2 %. And the chromaticity accuracy of the instrument shall be below:


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Lamp

Measurement PortSpecular Point

Baffle

= 8-10°

DUT

Lamp

= 8-10°

Table 1 Chromaticity Accuracy of the Instrument

x,y ±0.002 (0.001 to 0.05 cd/m2)

x ±0.0015 (0.05 cd/m2 or more)

y ±0.001 (0.05 cd/m2 or more)

6.1.3.3 The measuring distance can be calculated and set that an LMD should include over 500 pixels of display at 2 degree FOV. The calculated distance should be noted in a report.

6.1.4 Viewing Direction

6.1.4.1 In the case of the uniform hemispherical diffuse illumination conditions, an integrating sphere, sampling sphere, or hemisphere shall be used. The configuration shall follow the standard di/8° to di/10° illumination/detection geometry, where di is the standard notation for diffuse. The basic viewing direction of this test is shown in Figure 1. However, for a specific case, other viewing directions, like perpendicular to the display can be used. The placement of the LMD should be located in front of the measurement port in the Fig1. The lamp should have the light intensity at least from 380 nm to 780nm range, continuously.

Figure 1An Example of Measuring Configuration with Sampling Sphere

7 Summary of Test Method7.1 Test Patterns

7.1.1 A centered window box occupying 4% of the screen area is used. The 100% intensity (e.g., 255 gray levels in 8 bits) for window box and the 40% intensity (e.g., 102 gray levels in 8bits) for background are applied. One of the test patterns is shown in Figure 2.


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Figure 2Test Pattern of 4% Window Box with 40% Gray Background

7.1.2 Each of the following eight colors in the 4% window box at the center of the screen is applied.

Red: (255, 0, 0)

Green: (0, 255, 0)

Blue: (0, 0, 255)

Yellow: (255, 255, 0)

Magenta: (255, 0, 255)

Cyan: (0, 255, 255)

Black: (0, 0, 0)

White: (255, 255, 255)

NOTE 1: It may be necessary to use some kind of a mask or stray-light-elimination tube to avoid veiling glare in the detector when measuring 4% window box colors.NOTE 2: The intensity of colors is based on 8 bits. However, for the other color bits, like 10 bits or 12 bits, the intensity of color should be changed.

7.2 Measuring Set-up

7.2.1 Electrical conditions, warm-up time and adequate integration time follow section 3.2 of IDMS 1.0 methods.

8 Procedure8.1 The following measuring procedure is recommended for the measuring of tristimulus values of each of colors.

Check and measure the conditions described in 6.1.1 and 6.1.2.

Set the display device and signal generator which can be operated for the test patterns described in 7.1.2.

Set the distance between display and LMD, which is described in 6.1.3.3.

Set the LMD which is perpendicular to the display in dark condition with directional light source or set the LMD which is di/8° to di/10° illumination/detection geometry with the sampling sphere.

Apply the eight test patterns at the display, which is described 7.1.2.

Measure the spectral radiance or tristimulus values at the center of the window box with eight test patterns, respectively.

Record the measurement data.

Record the measurement conditions which are room conditions, aging conditions, and ambient conditions.

9 Calculations9.1 Analysis Method for Color Reproduction


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9.1.1 The 17 gradation points between black and other primary and secondary (RGBYMC) colors using gamma 2.2 should be calculated. The calculation method is described in Appendix 1-2.

9.1.2 The measured and interpolated data for all defined colors shall be transformed into the CIECAM02 3 dimensional color space, which is described in Appendix 1-1. The number of scattered points is 98 without overlapping points.

NOTE 3: For example, the number of points between black and red is 17. Because black is common point, 16 points are considered, respectively, and the number of scattered points is 96(=16 x 6). Finally, black and white points are added. The total number of scattered points is 98.

9.1.3 Color reproduction which is color gamut volume with brightness, colorfulness, and hue of the transformed data is calculated.

Search the color boundary surface in 3-dimensional color space, which is determined by a color gamut’s extremes.

Figure 3An Example of Color Reproduction

Set the smallest triangulation of surface points which are the nearest each other. One of the points ‘inner’ in Figure 4 is located at a middle of black and white points. Brightness (Q) which is related on m is z-coordinate. m value is Q. Colorfulness (M) which is the length from z-coordinate on xy plane and hue (h) which is the angle of colorfulness are related on k and l. k is M*cos(h), which is x-coordinate, and l is M*sin(h) which is y-coordinate.

Figure 4The Geometry of Trigonal Pyramid of Connecting Points with an Inside point

Calculate the color volume of trigonal pyramid and add up all volume of trigonal pyramids. The total number of trigonal pyramids is 192. The calculation procedure to get the total number is described in Appendix 1-3.

V N=16|( p⃗N×q⃗N )⋅⃗r N| where N = {1,2,3, …, 192} (1)

Color Volume=∑

NV N

9.2 Analysis Method for Perceptual Contrast

9.2.1 PCL is the length between black and white brightness. The calculation method for brightness is described in Appendix 1-1.

Calculate the contrast length between black and white brightness.


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(kr, lr, mr)

(kq, lq, mq)(kp, lp, mp)

(kinner, linner, minner) rN

qNpN



Date: 5/18/23

PCL = white brightness – black brightness (2)

10 Report10.1 The color reproduction named VCRC (Volume Color Reproduction Capability) in 3D color space is represented with percent relative to sRGB color volume in CIECAM02. An example of report table is shown in Table 2.

VCRC (%) = (Color Volume of Display/ (Color Volume of sRGB)) x 100 (3)

Table 2 An Example of a Result Report for the VCRC

Volume of sRGB 836,906.93

Color volume of display 836,906.93VCRC (%) 100

10.2 For the PCL, there is a table of the result report which is shown in Table 3.

Table 3 A Worked Example of a Result Report for the Perceptual Contrast LengthLuminance(cd/m2) Brightness PCL

Black 0.8575 61.5228

White 607 289.5The condition of Environment 0 lux


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APPENDIX 1 Color Space Conversion MethodNOTICE: The material in this Appendix is an official part of SEMI [designation number] and was approved by full letter ballot procedures on [A&R approval date].

A1-1 CIECAM02 color modelA1-1.1 A color appearance model provides a viewing condition specific method for transforming tristimulus values to and from perceptual attribute correlations. The CIECAM02 is useful for color management applications. This model consists of a chromatic adaptation transform and equations for computing a set of perceptual attribute correlations. A set of perceptual attributes is only focused on dim condition for the display application. Also, brightness color space for color reproduction is used, instead of lightness color space of CIELAB or CIELUV. Brightness is defined by the CIE as the attribute of a visual sensation according to which an area appears to emit more or less light.A1-1.2 The normalized tristimulus values to a long, medium and short wavelength sensitive space conversion

[ RGB ]=M cat 02[X

YZ ]

(A1-1)where;

M cat 02=[ 0 . 7328 0 . 4296 - 0 .1624-0 . 7036 1 .6975 0 .00610 . 0030 0 .0136 0. 9834 ]

(A1-2)

A1-1.3 The degree of adaptation to the white point calculation

D=0.9 [1− 13 .6

e(−(LA+42 )92 )] (A1-3)

where;

LA: one-fifth of the measured white luminance.

A1-1.4 The weighted chromatic adaptation with D factor calculationRc=[ (Y W D /RW )+(1−D)] RGc=[ (Y W D /GW )+(1−D )] GBc=[ (Y W D / BW )+(1−D )]B (A1-4)

where;

RW, GW, and BW: the RGB values computed for the white point.

A1-1.5 The viewing condition dependent constants calculation

k=1/(5 LA+1)FL=0 .2k 4(5 LA )+0 .1(1−k4)2(5LA )1 /3

n=Y b /Y W

Nbb=N cb=0.725(1/n )0. 2

z=1 .48+√n (A1-5)where;

Yb: 20,

Yw: 100.


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A1-1.6 Hunt-Pointer-Estevez space conversion for applying the post-adaptation non-linear compression

[R 'G'B ' ]=M HPE M

−1cat02[Rc

Gc

Bc]

(A1-6)where;

M HPE=[0 . 38971 0 . 68898 - 0 .07868-0 . 22981 1 .18340 0 .046410 . 00000 0 . 00000 1. 00000 ]

M cat 02−1 =[1 . 096124 −0. 278869 0 . 182745

0 . 454369 0 . 473533 0 . 072098−0. 009628 −0. 005698 1 . 015326 ]

(A1-7)

A1-1.7 Post-adaptation non-linear compression

R 'a=400( FL R '/100 )0. 42

27 . 13+(F L R '/ 100)0 . 42+0 .1

G 'a=400( FL G '/ 100 )0. 42

27 . 13+( FL G '/ 100 )0 .42 +0. 1

B' a=400(F L B '/ 100)0 . 42

27 . 13+( FL B '/ 100 )0.42 +0 . 1(A1-8)

A1-1.8 Temporary Cartesian representations and hue calculationa=R 'a−12 G'a /11+B 'a /11b=(1/9 )( R 'a+G'a−2B ' a)h=tan−1(b /a) (A1-9)

A1-1.9 The achromatic response calculation

A=[2 R ' a+G 'a+(1 /20 )B ' a−0.305 ] Nbb (A1-10)

A1-1.10 Lightness is calculated from the achromatic signals of A and AW

J=100 ( A / Aw )0 .59 z(A1-11)

A1-1.11 Brightness calculation

Q=(4 /0 .59 )√J /100( Aw+4 )FL0. 25 (A1-12)

A1-1.12 Temporary magnitude quantity, t calculation

t=0 .9 (50000 /13) N cb e t√a2+b2

R 'a+G 'a+(21/20 )B 'a (A1-13)where;

e t=1/4 [cos (h π180

+2)+3 .8] (A1-14)

A1-1.13 chroma, C calculation


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C=t0. 9√ J /100(1 .64−0 . 29n )0 .73(A1-15)

A1-1.14 colorfulness, M calculation

M=CF L0 . 25

(A1-16)

A1-2 Color conversionA1-2.1 Luminance of interpolated gradation points should be calculated, as follows:

LColorn=(LColor max

−LColormin)( n

255 )2.2

+LColor min (A1-17)where;

LColor_max: maximum luminance among 6 colors which is defined below

LColor_min: luminance of black

Color: red, green, blue, cyan, magenta, yellow

n = {0, 16, 32, 48, 64, 80, 96, 112, 128, 143, 159, 175, 191, 207, 223, 239, 255}

NOTE 4: The intensity of n is based on 8 bits (0~255). However, for the other color bits, like 10 bits or 12 bits, the intensity of n should be changed based on display color bits.

A1-2.2 Tristimulus values between black and other primary and secondary (RGBYMC), which is interpolated gradation points should be calculated with LColor_n.

XColor n=

xColor

yColorLColorn

Y Color n=LColor n

ZColor n=

1−xColor− yColor

yColorLColorn (A1-18)

where;

Color: red, green, blue, cyan, magenta, yellow

n = {0, 17, 33, 49, 65, 81, 97, 113, 129, 144, 160, 176, 192, 208, 224, 240, 255}

NOTE 5: The intensity of n is based on 8 bits (0~255). However, for the other color bits, like 10 bits or 12 bits, the intensity of n should be changed based on display color bits.

A1-2.3 The interpolated gradation points shall be transformed into the CIECAM02, which is described in A1-1.

A1-3 Trigonal pyramidsA1-3.1 The nearest colors can be set, as follow:

Color set C = {red-yellow, yellow-green, green-cyan, cyan-blue, blue-magenta, magenta-red}

A1-3.2 For example, the black point is the starting point at a magenta-red element of C. It should be connected with two points to make the triangulation. An example for describing connection points is shown in Figure A1-1, which shows points between magenta and red. There are black and M17, R17 and Black. It is the first triangulation with these three points.


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Figure A1-1 An Example of Points

A1-3.3 The M17 is the starting point. It should be connected with M33 and R17. The second triangulation is set with these points.

A1-3.4 The R17 is the starting point. It should be connected with M33 and R33. The third triangulation is set with these points.

A1-3.5 Finally, The R255 is the starting point. It should be connected with M255 and White. It is the 32rd triangulation.

A1-3.6 The total number of triangulation is 192, as the number of triangulation is 32 at each element of color set C which is described in A1-3.1, respectively.

A1-3.7 To get the trigonal pyramid, each of them is connected with an inner point, which is located at a middle of black and white.

NOTICE: Semiconductor Equipment and Materials International (SEMI) makes no warranties or representations as to the suitability of the Standards and Safety Guidelines set forth herein for any particular application. The determination of the suitability of the Standard or Safety Guideline is solely the responsibility of the user. Users are cautioned to refer to manufacturer’s instructions, product labels, product data sheets, and other relevant literature, respecting any materials or equipment mentioned herein. Standards and Safety Guidelines are subject to change without notice.

By publication of this Standard or Safety Guideline, SEMI takes no position respecting the validity of any patent rights or copyrights asserted in connection with any items mentioned in this Standard or Safety Guideline. Users of this Standard or Safety Guideline are expressly advised that determination of any such patent rights or copyrights, and the risk of infringement of such rights are entirely their own responsibility.


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