Tiêu chuẩn iso ts 19567 1 2016

The t extur r prod ction is depen ent on fr q ency an contras be ause the noise r d ction an the acutanc en anc ment, et c.. 4.2 Environments for measurementThe measur ment shal becar ie

Photog raphy — Dig ital cameras

Part 1:

Ph to ra hie — Caméras n mériques — Me sura e s de la

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the r eq eser

ISO c pyrig ht ofic

F reword i v

Introduction v

1 Sc ope 1

2 Nor mati ve r eferenc es 1

3 Terms and definitio s 1

4 Test c onditio s 1

4.1 General 1

4.2 Envir onment for measur ement 2

4.3 A pp r atus an har dwar e 2

4.4 A rr ang ement of measuring eq ipment 2

4.4.1 Refle tive tes chart 2

4.4.2 Transmis ive tes chart 2

4.5 Lighting 3

4.6 Camera seting s 3

5 Tex ture reproductio me surement proc edur e 4

5.1 General 4

5.2 Multiburs measur ement 5

5.2.1 L w contras multiburs chart 5

5.2.2 Measur ement method 6

5.3 Siemens s ar measurement 7

5.3.1 L w contras sinesiemens s ar chart 7

5.3.2 Measur ement method 7

6 Presentatio s of r esults 8

6.1 General 8

6.2 Multiburs measur ement 8

6.3 Siemens s ar measurement 8

A nne x A (informative)Categ orizatio of te x ture .10

A nne x B (informative)Ex posure c onditio for the me sur ement 11

A nne x C (informative) Interpretatio of me sur ement results 14

A nne x D (informative) Me sur ement results of multibur t and siemens star 16

Biblog raphy 20

ISO (he Int ernational Org nization for Stan ardization) is a worldwidefede ation of national s an ards

b dies (ISO membe b dies) The work of pr p ring Int ernational Stan ards is normaly car ied out

through ISO t ech ical committ ees Each membe b dy int er st ed in a subje t for w hich a t ech ical

committ ee has be n es a lshed has the right t o be r pr sent ed on that committ ee Int ernational

org nizations, g ove nmental an non-g ove nmental, in laison with ISO, also take part in the work

ISO cola orat es closely with the Int ernational Ele trot ech ical C mmis ion (IEC) on al matt ers of

ele trot ech ical s an ardization

The proc d r s used t o develo this document an those int en ed for it furthe maint enanc ar

desc ibed in the ISO/IEC Dir ctives, Part 1 In p rticular the dife ent a pro al c it eria ne ded for the

dife ent ty es of ISO document should be not ed This document was draft ed in ac ordanc with the

edit orial rules of the ISO/IEC Dir ctives, Part 2 ( e www.iso.org dir ctives)

A tt ention is drawn t o the p s ibi ity that some of the element of this document ma be the subje t of

p t ent right ISO shal not be held r sp nsible for identifying any or al such p t ent right Detais of

any p t ent right identified d ring the develo ment of the document wi be in the Introd ction an / r

on the ISO ls of p t ent de larations r c ived ( e www.iso.org p t ent )

Any trade name used in this document is information given for the convenienc of use s an does not

cons itut e an en orsement

F or an ex lanation on the meaning of ISO spe ific t erms an ex r s ions r lat ed t o conformity

as es ment, as wel as information a out ISO’ s adhe enc t o the WTO principles in the Te h ical

Bar ie s t o Trade (TBT) se the fol owing URL: F or word - Sup lementary information

The committ ee r sp nsible for thisdocument is ISO/TC42, Ph to ra h

Textur g ene al y means the visual an tactie surfac q alty de ived from the physical ty of the

mat erial an the rough es or grainines of the surfac F or digital s i came as, t extur is of course

the visual surfac q al ty an the charact eris ic of t extur r prod ction in the ca tur d imag e is

int erpr t ed int o the r prod ction of the low contras fine detais This Te h ical Spe ification spe if ies

the measur ment of how came as r prod c t extur defined as low contras fine detai s

The t en ency t o uti iz smal sensors with high pix el count in some came as lea es a ve y smal amou t

of lght r aching the individ al pix el W ith the signal g et ing smale an the noise level r maining at

a c rtain level, it is ne es ary t o r d c the noise in the imag e proc s ing aft er ca turing the imag e

Although the alg orithmsused for noise r d ction have be n develo ed over time, they ar s i l not a le

t o dife entiat e t extur in the actual sc ne from the u want ed noise introd c d b the ca turing sy st em

This de r ases the imag e q alty an it is the efor helpful t o ha e a method t o measur the los of

t extur Textur can also be en anc d t o inc ease the acutanc of the imag e The t extur r prod ction

is depen ent on fr q ency an contras be ause the noise r d ction an the acutanc en anc ment,

et c ar nonl nearly depen ent on the pix el v lue an the dife enc among the sur oun ing pix els

This part of ISO 1 5 7 spe ifies methods t o measur t extur r prod ction using t es chart with cyclc

patt erns The t es chart ar b sed on the es a l shed measur ment methods, multiburs (IEC

61146-1) an siemens s ar (ISO 1 2 3) This part of ISO 1 5 7 new ly def ines the density of the t es chart

an ex osur set ing of measur d came as The measur ment r sult ar pr sent ed in the sp tial

fr q ency r sponse ( SFR)curves

If one SFR is larg er than the othe in al fr q ency rang e, larg er amou t of t extur is r prod c d in the

cor esp n ing imag e If two SFRs ha e a c os p int an the larg er SFR depen s on the fr q ency rang e,

the supe ior imag e in the subje tive ev luation is depen ent on the dominant fr q ency of the imag e

Comp rison of the measur ment r sult pro ides imp rtant information in the t extur comparison of

the ca tur d imag es

Textur in a r al sc ne consis s mos ly of non-s ructur d or ran om p tt erns as shown in Annex A

Although it has be n conf irmed b ex e iment (Annex C an An ex D) that the t extur r prod ction

charact eris ics of mos came as ar wel r pr sent ed b the measur ment in this Te h ical

Spe ification, some came as ar foun t o in icat e dife ent charact eris ics for s ructur d patt erns

comp r d t o those for non-s ructur d patt erns Measur ment methods using non-s ructur d or

ran om p tt erns ar u de s u y an ar ex e t ed t o be inclu ed in conseq ent p rt t o this Te h ical

Spe ification

Photog raphy — Dig ital cameras — Tex ture reproduction

This part of ISO 1 5 7 spe if ies a prot ocol t o measur the t extur r prod ction in the imag es ca tur d

an proc s ed b digital came as inclu ing came as in othe devic s, e.g in came a phones

This p rt of ISO 1 5 7 spe ifies prot ocols for the measur ment of the t extur r prod ction using t es

chart with cyclc p tt ern

This part of ISO 1 5 7 ex clu es the ac epta le rang e of v lue for t extur r prod ction

2 Normati ve r eferences

The folowing document , in w hole or in p rt, ar normatively r fe enc d in this document an ar

in ispensa le for it a pl cation F or dat ed r fe enc s, only the edition cit ed a pl es F or u dat ed

r fe enc s, the lat es edition of the r fe enc d document ( inclu ing any amen ment )a pl es

IEC 619 6- 2-1:1 9 , Multimedia sys tems a d eq ipment — Colo r meas ur ment a d ma a ement —

Part 2-1: Colo r ma a ement — Defult R GB c olo r s pac e —sR GB

IEC 6 19 6- 2-1 Amd 1:2 0 , Multimedia sys tems a d eq ipment — Colo r meas ur ment a d

ma a ement — Part 2-1: Colo r ma a ement — Defult R GB c olo r s pac e —sR GB

3 Terms and definitions

F or the purposes of this document, the folowing t ermsand definitions a ply

3.1

texture

low contras f ine detais, w hich a pear in o je t

E AMP E Low contrast f ine details, which is visible in fliag , f r, s and, tex ties, g as s, o mas on y s urac es

3.2

texture reprod ctio

r sp nse in the output imag e of came as t o the t extur of the o je t in the sc ne

4 Test conditions

The folowing measur ment con itions should be used as nominal con itions w hen measuring the

t extur r prod ction of a digital came a

4.2 Environments for measurement

The measur ment shal becar ied out in the folowing environment u les othe wise s at ed:

— Tempe atur :2 °C± 3 °C

4.3 A pparatus and hard ware

Eithe a r fle tive chart or a transmis ive chart ma be used The l ght flux from the targ et shal be

dif used and shal not inclu e any spe ular component

4.4 A rrang ement of measur ing equipment

4.4.1 Reflecti ve test chart

The ar ang ement of the measuring eq ipment for a r fle tive t es chart shal be set up as shown in

Figur 1 The came a shal be p sitioned so that it cas s no shadow on the chart The lamps shal be

p sitioned at an angle w hich a oids dir ct spe ular r fle tion from the t es chart ent ering the came a

f

Figure 1 Ar ang ement of me suring equipment for reflective test chart

4.4.2 Transmis i ve test chart

The ar ang ement of the measuring eq ipment for a transmis ive t es chart hal be set up as shown in

Figur 2

Figure 2 — Ar ang ement of me suring equipment for transmis ive test chart

4.5 Lig hting

Colour t empe atur ofi lumination shal be 5 7 0 K ± 1 0 0 K Any i uminanc level of the t es chart

ma be a pled for the t extur r prod ction measur men howeve , the i luminanc level in the rang e

from 1 0 0 lx t o 2 0 0 lx ( in the case of transmis ive chart, from 5 ,3 cd/m2 t o 1 5 cd/m2 for 1 %

gra ) is r commen ed w hen the measur ment has no spe if ied purpose (e.g low l ght pe formanc )

Non-uniformity of i umination on the chart shal be les than 1 % The lght sour e( ) should be

p sitioned t o pro ide uniform i lumination an prod c no glar or spe ular r fle tions from the targ et

A flckering l ght sour e is not r commended as it ma cause b n ing art efact t o oc ur in the ca tur d

imag e In the case of using a flckering l ght sour e, although it is not r commen ed, the ex osur time

shal not be short er than one pe iod of the flckering t o minimiz the b n ing art efact caused b the

l ght our e

4.6 Camera set ing s

The ex osur should be adjust ed t o give the output v lue for the b ckgrou d gra near the c ntr of the

measur d chart t o be the v lue cor esp nding t o the input v lue defined below in the came a ’ s output

colour spac

( input luminanc for gra ) = (ma input luminanc ) × (gra r fle tanc )

F or sRGB came as, the output Y for 1 % gra is 1 8 ( 8-bit)

The deviation of the ex osur should be betwe n + % an − 0 % of the afor mentioned targ et

ex osur F or ex mple, the mean output luminanc Y v lue for the 1 % gra should be 1 8 ( 8-bit) +2,

−6 w hen the output colour sp c of the came a issRGB 8-bit (IEC 6 19 6- 2-1 an IEC 6 19 6- 2-1 Amd 1)

The ex osur shal be in the rang e of the afor mentioned deviation w hen the measur ment r sult of

multiple came asar comp r d (An ex B ex lains the b sic conc pt for this s ipulation) The ex osur

ma be adjust ed b the ex osur bias set ing of the came a or b ad ing a w hit e or black card t o the

t es chart

Whit e b lanc should be adjust ed t o r n e the c ntr of the imag e, asneutral as p s ible

Thefocusing shal be in the bes practical y at aina le focus

F or a came a with use sele ta le compr s ion ratio (e.g JP G), the compr s ion ratio should be

minimum t o minimiz the art efact of compr s ion The t extur r prod ction for RAW format imag e

data should be measur d for the output of the RAW conve t er sof war The name an the set ing of the

RAW conve t er shal be r p rt ed with the r sult of the measur ment

Othe set ings, such as “ harpnes ” , “ noise r d ction” , shal be in the default mode (fact ory ship ing

con ition) if those set ings ar not r p rt ed

5 Tex tur e reproduction measurement proc edure

5.1 General

Textur r prod ction is measur d b the ampltu e of a sine wa eform in this p rt of ISO 1 5 7 The

fr q ency charact eris ics of the t extur r prod ction ar measur d for v rious fr q encies in thesine

chart t o be ca tur d

Two measur ment methods, the multiburs and siemens s ar, ar def ined in this p rt of ISO 1 5 7

The multiburs chart consis s of seve al low contras sine wa es of disc et e fr q ency ( e Figur 3)

Each sine wa e consis s of multiple cyclc p tt erns along a single dir ction in the multiburs chart The

siemens s ar chart consis s of a low contras sine wa e-mod lat ed s ar burs p tt ern ( e Figur 4),

w hich inclu es contin ous fr q ency v riation in al dir ctions Based on the s ructur of each chart,

the multiburs an the siemens s ar can be used in thecasesshown in Ta le 1

Table 1 — Guidance for selecting the me surement

(1) In t he case of me suring S R with v rificat ion of t he

w av form an the amplitu e of t he ca ptured image

(1 1) In the case w hen skiled engine r eco nizes

the SFR ap ro imately from the waveform of the

captured imag e of the multibur t an verif ies that

the me sured SFR mat ches the reco nized outline

(1– 2) In the case of me suring SFR an the

wave-form simultane usly t o se the transient response

such as over ho ting an u der ho ting

(1) In the case of me suring SFR by simply ap lying

the sof ware to the captured ima e

(2) In the case of me suring SFR with high precision

along a single direction for a dis rete freq ency

The result of multib r t has higher precision

especialy for lower freq ency than siemens star

by avera ing the pix el value in the direction per

-pen icular to the me surement direction an by

avera ing the amplitu e of multiple cycles of the

eq al freq ency along the me surement direction

The alignment of the chart an the width of

aver-a ing shal b adjusted to av oid mis alculation

especialy for higher freq ency

(2) In the case of me suring SFR along multiple direc

-tions for contin ous freq encies

(3) In the case of using sof ware g neraly ap lied for

me suring an displaying the digital v alue an the

waveform of the ima e

For multibur t, it is e sier t o me sure the ampli

tu e for a certain freq ency using such sof ware

b cause it consists of multiple cycles at the same

freq ency

(3) In the case of using sof ware specialy designed

for the me surement of the te ture reprod ction

5.2 Multibur t measur ement

5.2.1 L w c ontrast multibur st chart

Figure 3 L w co trast sine multib r t chart (g eneral specificatio )

is r fle tanc of gra c ntr w hich is eq al t o r fle tanc of the b ckgroun gra

The chart inclu es l ght an dark pat ches adjac nt t o sine wa es, w hich se ve as r fe enc ar as for

bright peak and dark b tt om v lues The r fle tanc of the pat ches is eq al t o the bright peak ( R

w) an

the dark b tt om ( R

b) of the sin soidal chart

F or transmis ive chart, eq iv lent ransmit anc isa pled

The r lative siz of the chart shal be les than or eq al t o 1 3 of the ima ing ar a t o sup r s the risk

of vignet ing

The t es chart defined in Figur 3 shal be used in t extur r prod ction measur ment Othe t es chart

with dife ent gra c ntr level an / r the dife ent ampltu e v lue ma also be used for measuring

the r prod ction of smal e or larg er ampltu e of t extur

5.2.2 Me surement method

The measur ment is pe formed as folow s

— A low contras sine multiburs chart, as shown in Figur 3, shal be ca tur d an the ampltu es of

each sine wa e in the multiburs p tt ern shal be measur d

— The measur d ampltu e v lues shal be lneariz d in the output colour spac encoding

— The l nearization shal folow the formula of the colour encoding of the output imag e In case of

sRGB imag e, the lnearization shal folow the formula of the sRG s an ard (IEC 619 6- 2-1 an

min[ ] for each

fr q ency The noise should be sup r s ed b a e a ing along the peaks an b ttoms of the

sine wa e pe pen icular t o the v riation

— Calculat e each l neariz d v lue S’

ma[ ] an S’

min[ ]

— Calculat e the lneariz d ampl tu e A[ ] b the formula A[ ] = S’

ma[ ] – S’

min[]

— Calculat e the mod lation A_norm[ ] b the normalzing A[] b the l neariz d ampltu e betwe n

the darkes p t ch an the bright es pat ch

is a lneariz d v lue for dark p t ch

— The mod lation as a function of the fr q ency shal be the r sult of the measur ment

NOTE 1 It is pos ible t o me sure te ture reprod ction responses in an given position an given freq ency

orientation by varying the position an angle of the multibur t chart with respect o the camera

NOTE 2 When sho ting with an e posure level which gives the outp t value for the 1 % gray to b 1 8 ( 8

-bit) as specif ied in 4.6, the cor espon ing in ut level b fore sR B g mma proces ing, wil b ap ro imat ely 4

( 8-bit digital) an the diference b tween bright pe k an dark b tt om wil b ap ro imately 4 ( 8-bit digital),

resulting in ap ro imately 1 % in contrast signals In case of other bit depth, those values wil b replaced by

cor espon ing code values

NOTE 3 T is is b sed on the concept of me suring charact eristic when reprod ced an displayed on an ide l

display (he concept of “=outp t refer ed”)

5.3 Siemens star me sur ement

5.3.1 L w c ontrast sine siemens star chart

Figure 4 — Low contrast sine siemens sta chart

R efle tanc of bright peak ( R

w), r fle tanc of dark b tt om (R

b), an r fle tanc of gra c ntr ( R

g) is

given in F ormulae (1), (2), (3)an (4 )

The p t ches arou d the siemens s ar shal inclu e a pat ch for the bright peak (R

w) an a p t ch for the

dark b tt om ( R

b) The bright es p t ch shal be the bright peak ( R

w) an the darkes p t ch shal be the

dark b tt om ( R

b)

F or transmis ion chart, eq iv lent transmit anc is a pled

The r lative siz of chart shal be les than 1 3 of the ima ing ar a t o sup r s the risk of vignet ing

The t es chart defined in Figur 4 shal be used in t extur r prod ction measur ment Othe t es chart

with dife ent gra c ntr level an / r the dife ent ampltu e v lue ma also be used for measuring

the r prod ction of smal e or larg er ampltu e of t extur

5.3.2 Me surement method

The measur ment is pe formed as folows

— St ep1: The s ar shal be locat ed using the four sur ou ding markers for the r gion of int er s

— St ep2: The imag e data v lue shal be lneariz d fol owing theformula of the colour encoding of the

output imag e In case of sRGB imag e, the l nearization shal folow the formula of the sRGB s an ard

(IEC 619 6- 2-1 an IEC 6 19 6- 2-1 Amd 1)

— St ep3: A user-sele ta le segmentation of the s ar ma be made

— St ep4:A minimum of 3 radi shal be analy sed b localzing the pix els along the radius an sele ting

the digital code v lues for thel neariz d imag e as a fu ction of the angle

— St ep 5: A sine curve with the ex e t ed fr q ency shal be f itt ed int o the measur d v lues b

minimizing the sq ar e ror

— St ep 6: The contras of the sinecurve shal be det ermined b normal zation t o mod lation betwe n

thedarkes p t ch an the bright es pat ch

— St ep 7 :The mod lation as a function of the fr q ency shal be the r sult of the measur ment

6 Presentations ofr esults

The measur ment r sult shal be pr sent ed as a gra h of the fr q ency charact eris ics ( SFR) of the

t extur ampltu e The pe formanc of the digital came as can be comp r d using the SFR Given

SFR measur ment of two dife ent came as, if one measur d SFR is gr at er than the othe ac os al

measur d spatial fr q encies, then a larg er amount of t extur is r prod c d in the cor esp nding imag e

On the othe han , if the gr at er SFR depen s on the fr q ency, then the supe ior t extur r prod ction

in a subje tive ev luation is depen ent on the fr q ency s ructur of the imag e C mp rison of the

measur ment r sult can pro ide imp rtant information a out the r lative t extur r prod ction of the

ca tur d imag es

The i luminanc level an the output luminanc Y v lue for b ckgrou d gra near the c ntr of the

measur ment chart shal be r p rt ed If the c ntr of the measur ment chart is not oc upied b the

b ckgrou d gra , the output Y shal be r p rt ed for the b ckgrou d gra at a measura le ar a near s

t o the c ntr of the chart If a targ et with densities othe than those def ined in 5.2 an 5.3 is used, the

r fle tanc or transmit anc of the targ et hal be r p rt ed

6.2 Multibur st measur ement

In the folowing ex mple, the SFR is measur d in one dir ction The r sult ma be pr sented in the gra ph

shown in Figur 5 w hen the SFR is measur d in m ultiple dir ctions b rotating the m ultiburs chart

Figure 5 — Example of the result of multib r t me surement

6.3 Siemens star me surements

In the folowing ex mple, the SFR is measur d for eight segment , each of w hich oc upies a 45° se t or