Iec Tr 62977-3-2-2016.Pdf

IEC TR 62977 3 2 Edition 1 0 201 6 01 TECHNICAL REPORT Electronic display devices – Part 3 2 Evaluation of optical characteristics – Mura IE C T R 6 2 9 7 7 3 2 2 0 1 6 0 1 (e n ) ® colour inside Inte[.]

IEC TR 62977- 3- 2

Editio 1.0 2 16-01

Elect ronic display devices –

Part 3- 2: Evaluat ion of opt ical charact erist ics – Mura

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IEC TR 62977- 3- 2

Edit io 1.0 2 16-01

Elect ronic display devices –

Part 3- 2: Evaluat ion of opt ical charact erist ics – Mura

FOREWORD 4

INTRODUCTION 6

1 Sco e 7

2 Normative referen es 7

3 Terms an def i ition 7

4 Stan ard me s rin con ition 8

4.1 Stan ard me s rin con ition 8

4.1.1 Stan ard me s rin en ironmental con ition 8

4.1.2 Stan ard me s rin darkro m con ition 8

4.2 Lig t me s rin device (LMD) 8

4 3 Me s rin setup

9 4.4 Test sig al 9

4.5 Me s rin con ition 10 5 Stan ard evaluation method 10 5.1 Me s rement data proces in method 1

0 5.2 Me s rement data proces in flow 10 5.2.1 General 10 5.2.2 Median fi ter proces 1

5.2.3 Tran formation to o p nent colour sp ce f om CIE XYZ 12 5.2.4 Con olution with the contrast sen itivity fu ction (CSF) of the h man vis al s stem 1

2 5.2.5 Tran formation to CIE XYZ fom the o p nent colour sp ce 12 5.2.6 Tran formation to CIELAB f rom CIE XYZ 12 5.2.7 a cor ection 13 5.3 Mura evaluation method 13 5.3.1 General 13 5.3.2 Lig tnes mura evaluation 13 5.3.3 Chroma mura evaluation 15 5.3.4 Mura evaluation 16 5.3.5 Me s rement re ort 16 6 Actual example 17 6.1 General 17 6.2 Evaluation o jects 17 6.3 Subjective evaluation 17 6.4 Evaluation by the method in icated inthis doc ment u in a p ratu 18 6.5 Cor elation b twe n s bjective evaluation an mura evaluation value 19 An ex A (informative) S-CIELAB model 2

A.1 General 2

A.2 S-CIELAB model 2

A.3 Sp tial sen itivity fu ction model ( wo-dimen ional CSF model) 2

An ex B (informative) Typ of mura 2

B.1 General 2

B.2 Clas ification of mura 2

An ex C (informative) Use case of a mura evaluation value 2

C.1 General 2

C.2 Example of a u e case of a mura evaluation value 2

An ex D (informative) Variou mura me s rement method 2

D.1 General 2

D.2 Comp rison of mura evaluation stan ard 2

Biblogra h 2

Fig re 1 – Me s rin layout 9

Fig re 2 – Example of input sig al 10 Fig re 3 – Me s rement data proces in flow ado tin the S-CIELAB model 1

Fig re 4 – Con e t diagram of re l-sp ce information integration 14 Fig re 5 – 3 × 3 neig b urho d domain 15 Fig re 6 – Evaluation o jects in a dark ro m 17 Fig re 7 – CSF fi ter images in o p nent colour sp ce 18 Fig re 8 – Cor elation of mura evaluation value an ITU-R s bjective evaluation values 19 Fig re A.1 – Flowc art of S-CIELAB calc lation 2

Fig re A.2 – Two-dimen ional CSF model 21

Fig re A.3 – Examples of the con olution of a two-dimen ional CSF fi ter for i u ion 2

Fig re B.1 – Clas ification of mura by forms an /or cau es 2

Ta le 1 – Example of re orted criteria of two-dimen ional LMD 9

Ta le 2 – Example of me s rement res lts f or a display s re n u iformity 16 Ta le 3 – ITU-R q al ty an imp irment s ales 17 Ta le 4 – Subjective evaluation res lts 18 Ta le 5 – Evaluation res lts by a p ratu 19 Ta le A.1 – Parameters for e c axis of the o p nent colour sp ce 21

Ta le C.1 – Example of a u e case of a mura evaluation value 2

Ta le C.2 – Example of s bjects to evaluate 2

Ta le D.1 – Comp rison c art of variou mura me s rement stan ard 2

INTERNATIONAL ELECTROTECHNICAL COMMISSION

_

Part 3-2: Evaluation of optical characteristics – Mura

1 Th Intern tio al Ele trote h ic l Commis io (IEC) is a worldwid org niz tio for sta d rdiz tio c mprisin

al n tio al ele trote h ic l c mmite s (IEC Natio al Commite s) Th o je t of IEC is to promote

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The main tas of IEC tec nical commit e s is to pre are International Stan ard However, a

tec nical commit e may pro ose the publcation of a tec nical re ort when it has col ected

data of a diff erent kin f rom that whic is normaly publs ed as an International Stan ard, f or

example "state of the art"

IEC TR 6 9 7-3-2, whic is a tec nical re ort, has b en pre ared by IEC tec nical

commit e 1 0: Electronic display devices

The text of this tec nical re ort is b sed on the fol owin doc ments:

En uiry draft Re ort o v tin

Ful information on the votin f or the a proval of this tec nical re ort can b f ou d in the

re ort on votin in icated in the a ove ta le

This publ cation has b en draf ted in ac ordan e with the ISO/IEC Directives, Part 2

A l st of al p rts in the IEC 6 9 7 series, publ s ed u der the general title Electro ic display

de ic s, can b fou d on the IEC we site

The commit e has decided that the contents of this publ cation wi remain u c an ed u ti

the sta i ty date indicated on the IEC we site u der "ht p:/webstore.iec.c " in the data

related to the sp cif i publ cation At this date, the publ cation wi b

• reconfirmed,

• with rawn,

• re laced by a revised edition, or

A bi n ual version of this publcation may b is ued at a later date

IMPORTANT – The 'colour inside' logo on the cov r pa e of this publ c tion in ic te

that it contains colours whic are considere to be us ful f or the cor e t

understa din of its conte ts Us rs s ould th ref ore print this doc me t using a

colour printer

Electronic display , for example l q id cry tal display (LCDs), plasma display p nels (PDPs),

organic l g t emis ion display (OLEDs), an so on, have grown p pular as display for hig

-q al ty images It is therefore in re sin ly imp rtant to me s re the image q al ty of

electronic display One factor degradin the image q al ty is non-u iformity, k own as ‘mura’

The mura is clas ified into thre typ s The first is luminan e mura, the secon is colour mura

The third is cal ed merely “mura” an in lu es luminan e mura an colour mura

simultane u ly It is imp s ible to recog ize luminan e mura an colour mura as completely

se arate o jects

Variou me s rement method a out luminan e mura an colour mura have b en re orted in

variou academic conf eren es There are also some stan ard f or these mura For example,

u if ormity of luminan e an c romaticity are sp cif ied in IEC IEC 617 7-3 -1, SEMU (SEMI

mura) is sp cified in SEMI D31-0 13 an u iformity me s rement is sp cified in IDMS

ver.1.0 sec 8 However there is no re ort whic cle rly provides the q antitative method for

the mura that is cal ed merely “mura” (se An ex D)

Therefore the majority of electronic display man f acturers are sti u in the l mit sample f or

vis al in p ction

This Tec nical Re ort, whic inten s to verify one mura me s rement method, s ows the

detai ed mura me s rement method an its in p ction exp riment res lts

The International Electrotec nical Commis ion (IEC) draws at ention to the f act that it is

claimed that compl an e with this doc ment may in olve the u e of a p tent

IEC takes no p sition con ernin the eviden e, val dity an s o e of this p tent rig t

The holder of this p tent rig t has as ured the IEC that he/s e is wi in to negotiate l cen es

either fe of c arge or u der re sona le an non-dis riminatory terms an con ition with

a pl cants throu hout the world In this resp ct, the statement of the holder of this p tent rig t

is registered with IEC Information may b o tained f rom:

1-7-1 Konan, Minato-k , Tok o, 10 -0 7 Ja an

Atention is drawn to the p s ibi ty that some of the elements of this doc ment may b the

s bject of p tent rig ts other than those identified a ove IEC s al not b held resp n ible f or

identifyin an or al s c p tent rig ts

ISO (www.iso.org/p tents) an IEC (htp:/p tents.iec.c ) maintain on-l ne data ase of p tents

relevant to their stan ard Users are en ouraged to con ult the data ases for the most up to

date inf ormation con ernin p tents

ELECTRONIC DISPLAY DEVICES –

Part 3-2: Evaluation of optical characteristics – Mura

This p rt of IEC 6 9 7, whic is a Tec nical Re ort, provides an o tical me s rin method of

mura for electronic display It def i es general me s rin proced res f or mura me s rement

an an evaluation method of electronic display

The f ol owin doc ments, in whole or in p rt, are referen ed in this doc ment an are

in isp n a le for its a pl cation For dated referen es, only the edition cited a pl es For

u dated referen es, the latest edition of the referen ed doc ment (in lu in an

b th luminan e an colour u even es whose l g tnes an c roma dif fer p rtial y fom the

b c grou d of a display s re n with the ex e tion of pixel defects

Note 1 to e try: In g n ral lg tn s mura a d c roma mura e ist simulta e u ly Mura e alu tio s ows th

d gre of s re n u iformity c n id rin h w b th lg tn s mura a d c roma mura aff ect h ma p rc ptio

Note 1 to e try: Th w/k c a n l is a lumin n e c mp n nt Th rg a d b/ c a n ls are a c romaticity

c mp n nt of e to gre n, blu to y low, re p ctiv ly

4 Sta dard measuring conditions

4.1 Sta dard me s ring conditions

4.1.1 Sta dard me s ring e vironme tal conditions

The stan ard me s rin en ironmental con ition sp cified in IEC 6 3 1-6-1:2 0 , 5.1, s ould

b a pled [1]

1

4.1.2 Sta dard me s ring d rkroom conditions

The stan ard me s rin darkro m con ition sp cif ied in IEC 6 3 1-6-1:2 0 , 5.2, s ould b

a pl ed [1]

4.2 Light me s ring de ic (LMD)

The LMD u ed f or me s rements of the display s ould b c ec ed for the fol owing criteria

an sp cif ied ac ordin ly:

• sen itivity of the me s red q antity;

• er ors cau ed by vei n glare an len f lare (i.e stray l g t in o tical s stem);

• er ors cau ed by camera noise (i.e dark c arge noise of a c arge coupled device (CCD) ;

• timin of data-ac uisition an alasin -ef fects;

• l ne rity of detection an data con ersion;

• resolution when u in a two-dimen ional LMD

A two-dimen ional LMD s c as a CCD are detector s ould b u ed f or these me s rements

When u in a two-dimen ional LMD, it s ould b calbrated, so that the me s rement res lts

cor esp n to those by the p int-me s rement LMD

A two-dimen ional LMD me s res a ma of luminan e an /or colour co rdinate values over

the me s rement are of the s re n The sp cification of the LMD u ed s ould b noted in

the re ort as s own in Ta le 1 f or example

_ _ _ _ _ _

1

Numb rs ins u re bra k ts ref er toth Biblo ra h

It is imp rtant to avoid moiré an f lic er eff ect when u in a two-dimen ional LMD If a moiré

p tern a p ars in the image, the me s rin con ition sp cified in IDMS version 1.0 Sec

8.2 s ould be a pl ed The me s rin con ition sp cified in IDMS ver 1.0 A4.2.1 s ould b

a pl ed to avoid the f lic er eff ect [3]

NOT 1 Th p int-me s reme t LMD me s re th lumin n e a d/or c lo r c ordin te at e c me s reme t

p int o th s re n A two-dime sio al LMD me s re th ma of lumin n e a d/or c lo r c ordin te o er th

me s reme t are of th s re n

NOT 2 A p int-me s reme t LMD u u ly h s hig er s n itivity th n a two-dime sio al LMD A two-dime sio al

LMD me s re th u iformity of th me s rin are more e siy th n a p int-me s reme t LMD

Table 1 – Ex mple of reporte criteria of two-dime sion l LMD

CC re olutio (me s reme t p ints)

A ful white or gray sig al is input into a display The input sig al level is determined by an

evaluator an it s ould b noted in the me s rement re ort

Figure 2 – Ex mple of input sig al

4.5 Me s rin con itions

The me s rin con ition are as f ol ows:

a) The s ut er sp ed (exp s re time) of the LMD s ould b determined so as to b

s n hronized with the display (or b c l g t s an timin

b) The dia hragm sto of the LMD s ould b determined so as to o tain the pro er

saturation level of the c arged ca acity of the image sen or (CCD, complementary metal

oxide semicon u tor (CMOS)

The evaluator s ould sp cify the factors of noise in the me s rin con ition an strive to

minimize those ef fects on the me s rement data

5.1 Me s reme t data proc s ing method

The me s rement data s ould b outputed as thre ma s of CIE t r ist imulu v alues (X, Y, Z)

u in the two-dimen ional LMD con tru ted in a CCD are detector an with CIE 19 1

Figure 3 – Me s reme t data proc s in flow a optin th S-CIELAB model

5.2.2 Me ia f ilter proc s

The me s rement data s ould b proces ed with a median fi ter to el minate the noise of the

LMD or the me s rin con ition or an other f actors

It is recommen ed to con ider whic fi ter size s ould b u ed in ac ordan e with the noise

level The amou t of median fi terin wi af fect the sp tial f eq en y analy is To minimize its

imp ct, a smal win ow size s ould b selected For example, a (3 × 3) pixels or (5 × 5) pixels

win ow size minimizes this imp ct By selectin these sizes, the elmination of the

b c grou d sen or noise of the LMD is sig ificant A multiple me s rement or lon exp s re

time is eff ective for el mination of this b c grou d noise

5.2.3 Tra sf ormation to opp ne t colour spa e from CIE XYZ

The f ol owin determinant s ould b a pled to con ert CIE XYZ to w/k, r /g, an b/y

A s re n image is p rceived throu h h man eyes Theref ore, it is imp rtant to con ider the

c aracteristic of the h man vis al s stem f or the evaluation The sp tial contrast sen itivity

f un tion is one u eful c aracteristic for the evaluation of s re n image q al ty (se An ex A)

NOT Th CS of th h ma vis al s stem d e n t h v is tro ic pro ertie , in ofar a th CS in th v rtic l

a d h riz ntal dire tio s is s p rior to th CS in th dia o al dire tio Th ref ore, it is b ter to c n id r u in a

mo ifie S-CILEAB mo el

5.2.5 Tra sformation to CIE XYZ f rom the oppone t colour spa e

The f ol owin determinant s ould b a pled to con ert w/k , r/g, an b/y to CIE XYZ

(2)

5.2.6 Tra sformation to CIELAB f rom CIE XYZ

The me s rement data s ould b con erted to CIELAB colour sp ce as sp cified in CIE 15

[2]

L* = 1 6 f(Y/Y

n) – 16

a = 5 0 [f(X/X

n) – f(Y/Y

n)]

b = 2 0 [f(Y/Y

n) – f(Z/Z

n)]

where

f(X/X

n) = (X/X

n)/3

if (X/X

n) > (2 /1 6)

3

f(X/X

n) = (8 1/10 ) X/X

n) + 16/116 if (X/X

n) ≤ (2 /1 6)

3

an

f(Y/Y

n) = (Y/Y

n)/3

if (Y/Y

n) > (2 /1 6)

3

f(Y/Y

n) = (8 1/10 ) Y/Y

n) + 16/1 6 if (Y/Y

n) ≤ (2 /1 6)

3

an

f(Z/Z

n) = (Z/Z

n)/3

if (Z/Z

n) > (2 /1 6)

n) = (8 1/10 ) Z/Z

n) + 16/1 6 if (Z/Z

n) ≤ (2 /1 6)

Here X

n, Y

n, an Z

nare determined as f ol ows

is the most feq ent value of Z in the me s rement data

The sl g t s if t of the white p int de en in on the input sig al level s ould not b ju ged as

mura However, if (X

n, Y

n, Z

n) are defined as the me s rement data at 10 % of f ul white input,

the whole s re n may b ju ged as a whole colour mura at another input level To avoid this

er or, (X

n, Y

n, Z

n) are defined in the a ove formula u in the most f eq ent value in e c

me s rement data

CIE 19 6 a,b (CIELAB) c roma, C*

a, sp cified in CIE 15 is calc lated in the formula b low

)/2

(8)

5.2.7 a* cor e tion

The a

*

value s ould b exp n ed by multiplyin by 1,4 if it is a p sitive value This a*

cor ection is des rib d in detai in [5] In the h man vis al s stem, a red is u even colour is

p rceived as a worse degre of mura than other colours In order to cor ect this h man

p rce tion whic is reflected in the Helmholtz–Kohlrau c eff ect, exp n ion of a

c roma mura analy is This mura evaluation method provides a degre of p rceived mura

The hig er the evaluation value, the worse the p rce tion of mura is

5.3.2 Lightn s mura e aluation

The purp se of this me s rement is to evaluate the l g tnes mura of the display s re n The

fol owin formula des rib d in [6] s ould b a pl ed to compute a l g tnes mura evaluation

value

LEV = 1,9 L

ma+ ,18 L

ml+ 19,9 L

o)

Lig tnes gradient is calc lated by a so el o eration In order to s p ort variou display sizes,

viewin distan es an resolution of LMD, the l g tnes ed e s ould b def i ed as a lg tnes

gradient p r degre of the o server's viewin an le, con iderin the h man vis al s stem

des rib d in [7] Sin e the so el value is the amou t of c an e per CCD pixel, the calc lation

method of the l g tnes ed e is re resented by the fol owin formula an its con e t is s own

Figure 4 – Conc pt dia ram of re l-spa e information inte ration

The thres old of the lg tnes ed e s ould also b defined as a l g tnes gradient p r degre

of the o server's viewin an le A l g tnes gradient of more than 13 p r degre on a display

s re n is determined as the l g tnes ed e as des rib d in detai in [7]

The l g tnes ed e are is computed as the pixel count ratio of the l g tnes ed e to the pixel

cou t of the whole s re n are

A so el o eration is con u ted to extract the major ed e of the image The f ol owin

determinant s ould b a pl ed f or the calc lation

W

L[mm]

1 d gre

Me s re s re n Ima e

H

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