Tiêu chuẩn iso ts 19264 1 2017

TECHNICAL SPECIFICATION ISO/TS 19264-1 First edition 2017-04 Photography — Archiving systems — Image quality analysis — Part 1: Reflective originals Photographie — Systèmes d’archivage — Analyse de la qualité d’image — Partie  1:  Documents  réfléchissants Reference number ISO/TS 19264-1:2017(E) © ISO 2017 ISO/TS 19264-1:2017(E) COPYRIGHT PROTECTED DOCUMENT © ISO 2017, Published in Switzerland All rights reserved Unless otherwise specified, no part o f this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission Permission can be requested from either ISO at the address below or ISO’s member body in the country o f the requester ISO copyright o ffice Ch de Blandonnet • CP 401 CH-1214 Vernier, Geneva, Switzerland Tel +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org ii © ISO 2017 – All rights reserved ISO/TS 19264-1:2017(E) Contents Page Foreword iv Introduction v Scope Normative references Terms and definitions System setup and calibration 10 4.1 4.3 4.4 4.5 4.7 4.8 4.9 General 10 10 Camera/scanner settings 10 Exposure 10 White balancing 11 11 Focusing 11 Colour encoding 11 Reproduction scale 12 6.1 6.2 6.3 6.4 General 13 Tones and noise 13 Colour 16 Details 18 20 4 6 I CC Pro filing Imaging system quality analysis procedure 12 Imaging systems quality characteristics and metrics 13 6.5 Sys tem co nfiguratio n Geo metry Reporting results 21 7.1 7.2 7.3 7.5 7.6 7.7 7.8 7.9 7.10 7.11 7.12 7.13 7.14 7.15 General 21 Example report for tone reproduction results 22 Gain modulation 23 24 Noise 24 Banding 26 Defect pixels 27 White balance 27 Colour reproduction 28 Colour mis-registration 29 Sampling rate 29 Resolution 29 MTF 50/MTF 10 29 Sharpening 29 Acutance 29 f 29 f 29 7.18 Distortion 29 7.19 Reproduction scale 29 Annex A (normative) Test chart requirements 30 Annex B (normative) Guidelines for imaging performance aims and tolerances 32 Annex C (informative) Example of multi-pattern chart: Universal Test Target (UTT) 34 7.4 D ynamic range 7.1 I lluminance no n- uni o rmity 7.1 C hro minance no n- uni o rmity Bibliography 55 © ISO 2017 – All rights reserved iii ISO/TS 19264-1:2017(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) The work o f preparing International Standards is normally carried out through ISO technical committees Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters o f electrotechnical standardization The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part In particular the different approval criteria needed for the di fferent types o f ISO documents should be noted This document was dra fted in accordance with the editorial rules of the ISO/IEC Directives, Part www.iso org/directives Attention is drawn to the possibility that some o f the elements o f this document may be the subject o f patent rights ISO shall not be held responsible for identi fying any or all such patent rights Details o f any patent rights identified during the development o f the document will be in the Introduction and/or on the ISO list of patent declarations received www.iso org/patents Any trade name used in this document is in formation given for the convenience o f users and does not constitute an endorsement For an explanation on the meaning o f ISO specific terms and expressions related to formity assessment, as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see the following URL: http://www.iso org/iso/ foreword html The committee responsible for this document is ISO/TC 42, Photography iv © ISO 2017 – All rights reserved ISO/TS 19264-1:2017(E) Introduction E le c tron ic i magi ng s ys tem s , s uch as s c an ners and c amera s , c an b e u s e d for d igiti z i ng phys ic a l re cord s , e.g documents, pictures, maps The resulting digital images can be more or less accurate in terms of how wel l they repro duce the origi na l re cord’s tone s , colou rs , de tai l s , e tc T he s e a nd o ther charac teri s tic s o f a d igita l i mage c an b e as s e s s e d b y i magi ng s ys tem s qua l ity ana lys i s I n genera l, the ach ievable acc u rac y o f d igita l repro duc tion s dep end s on the natu re o f the origi na l re cord a nd the d igiti z ation, e s p e ci a l ly the p er forma nce o f the i magi ng s ys tem and the appl ie d s ys tem s e tti ngs In s ome organ i z ation s , e g with i n the a rch ivi ng a nd c u ltu l heritage field , where s iderable re s ource s are put i nto d igiti z ation proj e c ts , it i s key to en s ure that the re qu i re d i magi ng s ys tem s qua l ity i s me t and that it i s s i s tent To th i s end, i magi ng s ys tem s qua l ity ana lys i s c a n a s s i s t tho s e developi ng or acqu i ri ng i magi ng s ys tem s with the as s e s s ment and veri fic ation o f s ys tem p er forma nce, s uch as the s p e c i fie d re s olution and dynam ic nge o f a s c an ner, a nd the comp arative p er formance o f d i fferent i magi ng s ys tem s I magi ng s ys tem s qua l ity a na lys i s i s a l s o u s e d i magi ng s ys tem s as wel l a s is used for for for s e tti ng up a nd c a l ibrati ng en h anci ng thei r p er formance Fi na l ly, i magi ng s ys tem s qua l ity a na lys i s as s e s s i ng acc u rac y and control l i ng i magi ng s i s tenc y over ti me No te, th at wh i le the ne e d to en s u re i magi ng s ys tem s qua l ity i s generic, the re qu i re d level o f i magi ng s ys tem s qua l ity a nd acc u rac y i s u s e - c as e s p e c i fic For exa mp le, when d igiti z i ng watercolou rs it i s u s ua l ly e s s enti a l to re ach a h igh degre e o f acc u rac y i n the c ap tu re o f the colou r i n formation, wh i le th i s i s no t norma l ly e qua l ly critical when digitizing newspapers Also, some image processing programs, such as Optical Character Recognition (OCR), are more accurate if the contrast is enhanced during imaging I n prac tice, i magi ng s ys tem s qua l ity i s a na lys e d b y d igiti z i ng a phys ic a l re ference targe t (te s t ch ar t) with known (measured) values and comparing these reference values to the corresponding captured Figure 1) va lue s repre s ente d i n the d igita l i mage fi le (s e e T he u s e o f a te s t ch ar t en s ure s th at the i magi ng s ys tem s qua l ity ch arac teri s tics c an b e de term i ne d obj e c tively H owever, to b e u s able the qua l ity o f the targe t ne e d s to exce e d the p er forma nce o f the i magi ng s ys tem For exa mple, to de term i ne the re s olution o f a n i magi ng s ys tem, the targe t ne e d s to have a te ch n ic a l p attern with more de ta i l s than the s ys tem i s c ap able o f re s olvi ng I magi ng s ys tem s qua l ity a na lys i s rep or ts how acc u rately the i magi ng s ys tem repro duce s the re ference targe t T here fore, i f the origi na l re cord d i ffers s igni fic a ntly from the targe t, e g with re s p e c t to tone, tona l range, colou rs , de tai l s , and l ight refle c tance/ab s orb a nce, th i s may, i n s pite o f a wel l p er form i ng s ys tem, comprom i s e the acc u rac y o f the repro duce d i mage S e e a l s o Re ference s [ 25 ] and [ 26 ] I de a l ly, the targe ts s hou ld re s emble the natu re o f the origi na l materia l However, given the ma ny d i fferent typ e s o f origi na l re cord s th i s i s o ften no t prac tic a l or te ch n ic a l ly i mp o s s ible E ven though s ys tem s may p er form d i fferently on the d i fferent typ e s o f origi na l s th i s c u ment provide s to ol s to veri fy i f a s ys tem i s acc u rately c a l ibrate d a nd i n genera l p er form s wel l on a s ele c te d typ e o f origi na l T h i s i s s u fficient i n mo s t c a s e s b e c au s e s ys tem s a re u s ua l ly de s igne d to nd le va riou s typ e s o f origi na l s ( b ei ng clo s e to the Luther cond ition) Per formance on s p e ci fic typ e s o f origi na l s however c an on ly b e veri fie d i f the to ol s are made o f that materia l I t i s a l s o i mp or ta nt to no te th at an acc u rate repro duc tion u s ua l ly re qu i re s s ub s e quent pro ce s s i ng to render a vi s ua l ly ple a s i ng i mage T here a re I S O s ta nda rd s for s ys tem s , noi s e, e g re s olution, obj e c tively me a s u ri ng d i fferent p er formance ch arac teri s tics o f i magi ng dyna m ic range, tone a nd colou r repro duc tion (s e e Clause 2) This c u ment combi ne s a l l o f the s tandard s th at relate to the i magi ng s ys tem s qua l ity a na lys i s for c u ltu l heritage a nd defi ne s a to ol s e t to apply them to the s e device s and workflows T he s e to ol s are b as e d on the use of a test chart with multiple technical patterns coupled with software that allows the user to ana lys e s evera l i magi ng s ys tem s qua l ity cha rac teri s tic s s i mu ltane ou s ly and re ceive comprehen s ive re s u lts However, the s e to ol s a re no t b a s e d on a s tandard i ze d i mage qua l ity a na lys i s me tho d , wh ich s c au s e d fu s ion a mong u s ers With the publ ic ation o f th i s s p e c i fication i magi ng s ys tem s qua l ity ana lys i s to ol s c an re fer to an I S O c ument To s s upp or t th i s b e en c ument a s tand ard with a glo s s ar y i nclud i ng a l l releva nt term s develop e d (I S O 19 62 ) Fu r ther th i s c ument is accomp an ie d by (ISO/TR 19263-1) that provides practical guidance on how to use this document © ISO 2017 – All rights reserved a and defi n ition s Te ch n ic a l Rep or t v TECHNICAL SPECIFICATION ISO/TS 19264-1:2017(E) Photography — Archiving systems — Image quality analysis — Part 1: Reflective originals Scope T h i s c u ment de s c rib e s a me tho d for a na lys i ng i magi ng s ys tem s qua l ity i n the a re a o f c u ltu l heritage i magi ng T he me tho d de s c rib e d a na lys e s mu ltiple i magi ng s ys tem s qua l ity cha rac teri s tics from a s i ngle i mage o f a s p e ci fie d te s t targe t T he s p e c i fic ation s tate s wh ich cha rac teri s tic s a re me as u re d, how they are me as u re d, and how the re s u lts o f the a na lys i s ne e d to b e pre s ente d T h i s s p e ci fic ation appl ie s to s c a nners and d igita l c amera s u s e d material NO TE T h i s c u ment add re s s e s i m agi ng o f re fle c tive or igi n a l s , a transparent originals for d igiti z ation o f c u ltu l heritage futu re p a r t two wi l l add re s s i m agi ng o f Normative references T he fol lowi ng c u ments are re ferre d to i n the tex t i n s uch a way th at s ome or a l l o f thei r content s titute s re qu i rements o f th i s c u ment For date d re ference s , on ly the e d ition cite d appl ie s For u ndate d re ference s , the late s t e d ition o f the re ference d c ument (i nclud i ng a ny amend ments) appl ie s ISO 12233, Photography — Electronic still picture imaging — Resolution and spatial frequency responses ISO 14524, Photography — Electronic still-picture cameras — Methods for measuring opto-electronic conversion functions (OECFs) ISO 15739, Photography — Electronic still-picture imaging — Noise measurements ISO 16067-1, Photography — Spatial resolution measurements of electronic scanners for photographic images  —  Part  1:  Scanners  for  reflective  media ISO 17957, Photography — Digital cameras — Shading measurements ISO 21550, Photography — Electronic scanners for photographic images — Dynamic range measurements CIE 15, Colorimetry Terms and definitions For the pu r p o s e s o f th i s c u ment, the fol lowi ng term s and defi n ition s apply ISO and IEC maintain terminological databases for use in standardization at the following addresses: — ISO Online browsing platform: available at http://www.iso org/obp — IEC Electropedia: available at http://www.electropedia org/ © ISO 2017 – All rights reserved ISO/TS 19264-1:2017(E) 3.1 acutance numerical value that correlates to some extent with subjective image sharpness [SOURCE: ISO 19262:2015, 3.1] 3.2 Adobe RGB 1998 three-component colour image encoding defined in Adobe RGB (1998) colour image encoding Note to entry: Adobe RGB 1998 Colour Image Encoding can be found under the following URL https://www adobe com/digitalimag/pdfs/AdobeRGB1998 pdf [SOURCE: ISO 12640-4:2011, 3.1, modified — addition o f the Note to entry.] 3.3 banding imaging unwanted stripes or bands that occur in a digital image Note to entry: Note1 to entry: Bands are usually caused by fixed pattern noise o f sensors in scanners, inter ference problems between electronic parts o f a camera, or by too-coarse quantization [SOURCE: to entry.] ISO 19262:2015 , 3.9, modified — addition o f “or by too-coarse quantization” in the Note 3.4 checkerboard regular squared dark and bright structure on a surface like the one used on a chess board [SOURCE: ISO 19262:2015, 3.18] 3.5 chroma, C* chromatic chromaticness, colour fulness, o f an area judged as a proportion o f the brightness o f a similarly illuminated area that appears white or highly transmitting [SOURCE: ISO/IEC 8613-2:1995, 3.18] 3.6 CIELAB colour space three-dimensional, approximately uni form colour space, produced by plotting, in rectangular coordinates L*, a *, b* Note to entry: This colour space has been designed to be device independent [SOURCE: CIE Publication 15 and ISO/IEC 5631-1:2015, 3.6, modified — Note to entry has been modified.] 3.7 colour sensation resulting from the visual perception of radiation of a given spectral composition [SOURCE: ISO 4618:2014, 2.58, modified — definition slightly changed and Note and Note to entry have been deleted.] 3.8 colour difference distinction between two colours observed or measured under standard conditions [SOURCE: ISO 12637-2:2008, 2.21] © ISO 2017 – All rights reserved ISO/TS 19264-1:2017(E) 3.9 colour encoding generic term for a quantized digital encoding of a colour space, encompassing both colour space encodings and colour image encodings [SOURCE: ISO/TS 22028-3:2012, 3.6] 3.10 colour misregistration colour-to-colour spatial dislocation o f otherwise spatially coincident colour features o f an imaged object [SOURCE: ISO 19262:2015, 3.42] 3.11 contrast di fference between the grey levels o f two specified parts o f the image [SOURCE: ISO 21227-1:2003, 3.5.3] 3.12 pixel defect pixel or subpixel that operates in a way other than the one in which it is driven [SOURCE: ISO 9241-302:2008, 3.4.30] 3.13 ΔE see colour difference [SOURCE: ISO 19262:2015, 3.63] 3.14 digital image digital file consisting o f picture elements (pixels) with one or more digital code values per pixel that represent a colour or tonal value [SOURCE: ISO 19262:2015, 3.73, modified — deletion o f the Note to entry.] 3.15 digital imaging process of creating digital images Note to entry: The term can also be used more generally to include digital image processing [SOURCE: ISO 19262:2015, 3.74] 3.16 digital imaging system system that records and/or produces images using digital data [SOURCE: ISO 12231:2012, 3.38] 3.17 digital still camera DSC device which incorporates an image sensor and produces a digital signal representing a still picture Note to entry: A digital still camera is typically a portable, hand-held device The digital signal is usually recorded on a removable memory, such as a solid-state memory card or magnetic disk [SOURCE: ISO 12231:2012, 3.40] © ISO 2017 – All rights reserved ISO/TS 19264-1:2017(E) 3.18 digitization act of generating a digital (quantized) representation of a continuous signal [SOURCE: ISO 20998-1:2006, 2.7, modified — Tne Note to entry has been deleted.] 3.19 distortion geometric distortion displacement from the ideal shape o f a subject (lying on a plane parallel to the image plane) in the recorded image Note to entry: It basically derives from variation o f lateral magnification in the image field o f a camera lens and results in straight lines being rendered as curves There are other factors to induce geometric distortion, for example rotational asymmetricity o f a camera lens or position shi ft processing in a camera imaging process [SOURCE: ISO 19262:2015, 3.82] 3.20 dynamic range difference, over a given luminance range, between maximum and minimum signal levels, expressed in decibels, contrast ratios or f-stops Note to entry: The minimum signal level needs to be greater than a specified usable signal level Note to entry: This definition is derived from IEC 702–04–23 but was altered to match the imaging and archiving application [SOURCE: ISO 19262:2015, 3.87] 3.20.1 ISO DSC dynamic range ratio of the maximum luminance level that appears unclipped to the minimum luminance level that can be reproduced with an incremental signal-to-temporal-noise ratio of at least 1, as determined according to ISO 15739 [SOURCE: ISO 12231:2012, 3.86] 3.20.2 ISO scanner dynamic range di fference o f the maximum density where the incremental gain is higher than 0,5, as determined according to ISO 21550 to the minimum density that appears unclipped [SOURCE: ISO 21550:2004, 3.13] 3.21 exposure H total quantity of light allowed to fall upon a photosensitive emulsion or an imaging sensor Note to entry: The exposure is measured in lux per second [SOURCE: ISO 10934-1:2002, 2.50, modified — A symbol, the field o f application and a note to entry have been added.] 3.22 fast scan direction scan direction corresponding to the direction of the alignment of the addressable photoelements in a linear array image sensor [SOURCE: ISO 16067-1:2003, 3.7] © ISO 2017 – All rights reserved ISO/TS 19264-1:2017(E) x 10 15 Gray bars vertical black vertical white ver tic a l gray Background Checkerboard fi rs t wh ite p atch fi rs t gre y p atch continued as checkerboard Vertical scale centre line mm lines mm lines 10 mm lines lettering 1/16 Inch lines 1/2 Inch lines Inch lines lettering surrounding white x 10 Aimed L* value Width Height y 0 5 300 300 300 y Width Height 0 10 10 10 10 Aimed L* value substrate white 50 E ach p atch i s s u r rou nde d b y a b l ack l i ne o f , m m th ickne s s with the line centre being the border of each patch x 30 29 28,5 27,5 y e ver y m m e ver y m m e ver y 10 m m Width Height 1,5 2,5 300 0 Aimed L* value max black max black max black max black Contour 0,19 0,19 0,19 0,19 e ver y 10 m m , Verd a n a p t on le ft s ide o f s c a le 30 30 30 e ver y /1 Inch e ver y /2 I nch e ver y I nch 1,5 2,5 0 max black max black max black 0,19 0,19 0,19 e ver y i nch , Verd a n a p t on r ight s ide o f s c a le 20 20 300 substrate behind both white gscales S c a le on top o f b ackgrou nd che ckerb o a rd a nd b eh i nd hori z onta l gre y b a rs Horizontal scale centre line mm lines mm lines 10 mm lines lettering 1/16 Inch lines 1/2 Inch lines Inch lines lettering surrounding white x e ver y m m e ver y m m ever y 10 m m y 272,4 272,4 272,4 272,4 Width 420 0 Height Aimed L* value 1,5 2,5 max black max black max black max black e ver y 10 m m , Verda n a p t on up p er s ide o f s c a le e ver y /16 I nch e ver y /2 I nch e ver y I nch 271,4 270,9 269.9 0 1,5 2,5 max black max black max black Contour 0,19 0,19 0,19 0,19 0,19 0,19 0,19 e ver y I nch , Verda n a p t on lower s ide o f s c a le 265 420 15 behind substrate white both scales S c a le on top o f b ackgro u nd che ckerb o a rd a nd b eh i nd ver tic a l gre y b a rs 44 © ISO 2017 – All rights reserved ISO/TS 19264-1:2017(E) In contrast to the rest of the features the position given for the grey scales describe the centre of each patch and not the lower left corner Left vertical grey scale GS_L_1 GS_L_2 GS_L_3 GS_L_4 GS_L_5 GS_L_6 GS_L_7 GS_L_8 GS_L_9 GS_L_10 GS_L_11 GS_L_12 GS_L_13 GS_L_14 GS_L_15 GS_L_16 GS_L_17 GS_L_18 GS_L_19 GS_L_20 Numbering Numbers on right side x 105 105 105 105 105 105 105 105 105 105 105 105 105 105 105 105 105 105 105 105 © ISO 2017 – All rights reserved 83,5 90,5 97,5 104,5 111,5 118,5 125,5 132,5 139,5 146,5 153,5 160,5 167,5 174,5 181,5 188,5 195,5 202,5 209,5 216,5 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 Colour orange Right vertical gray scale GS_R_1 GS_R_2 GS_R_3 GS_R_4 GS_R_5 GS_R_6 GS_R_7 GS_R_8 GS_R_9 GS_R_10 GS_R_11 GS_R_12 GS_R_13 GS_R_14 Width y Height 7 7 7 7 7 7 7 7 7 7 Aimed L* 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 Density 0,06 0,12 0,18 0,25 0,32 0,39 0,47 0,55 0,64 0,73 0,84 0,95 1,07 1,21 1,36 1,52 1,72 1,95 2,26 D max > 2,3 Typo Verdana 8pt x 315 315 315 315 315 315 315 315 315 315 315 315 315 315 y 216,5 209,5 202,5 195,5 188,5 181,5 174,5 167,5 160,5 153,5 146,5 139,5 132,5 125,5 Width Height Aimed L* 15 15 15 15 15 15 15 15 15 15 15 15 15 15 7 7 7 7 7 7 7 95 90 85 80 75 70 65 60 55 50 45 40 35 30 Density 0,06 0,12 0,18 0,25 0,32 0,39 0,47 0,55 0,64 0,73 0,84 0,95 1,07 1,21 45 ISO/TS 19264-1:2017(E) Right vertical gray scale GS_R_15 GS_R_16 GS_R_17 GS_R_18 GS_R_19 GS_R_20 Numbering Numbers on left side y 118,5 111,5 104,5 97,5 90,5 83,5 Colour orange Upper horizontal gray scale GS_U_1 GS_U_2 GS_U_3 GS_U_4 GS_U_5 GS_U_6 GS_U_7 GS_U_8 GS_U_9 GS_U_10 GS_U_11 GS_U_12 GS_U_13 GS_U_14 GS_U_15 GS_U_16 GS_U_17 GS_U_18 GS_U_19 GS_U_20 Numbering Numbers on lower side GS_D_1 GS_D_2 GS_D_3 GS_D_4 GS_D_5 GS_D_6 GS_D_7 GS_D_8 Width Height Aimed L* 15 15 15 15 15 15 7 7 7 Density 25 20 15 10 1,36 1,52 1,72 1,95 2,26 D max > 2,3 Aimed L* Density Typo Verdana 8pt x 276,5 269,5 262,5 255,5 248,5 241,5 234,5 227,5 220,5 213,5 206,5 199,5 192,5 185,5 178,5 171,5 164,5 157,5 150,5 143,5 y 212,5 212,5 212,5 212,5 212,5 212,5 212,5 212,5 212,5 212,5 212,5 212,5 212,5 212,5 212,5 212,5 212,5 212,5 212,5 212,5 Colour orange Lower horizontal gray scale 46 x 315 315 315 315 315 315 Width Height 7 7 7 7 7 7 7 7 7 7 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 0,06 0,12 0,18 0,25 0,32 0,39 0,47 0,55 0,64 0,73 0,84 0,95 1,07 1,21 1,36 1,52 1,72 1,95 2,26 D max > 2,3 Typo Verdana 8pt x 143,5 150,5 157,5 164,5 171,5 178,5 185,5 192,5 y 87,5 87,5 87,5 87,5 87,5 87,5 87,5 87,5 Width Height Aimed L* 7 7 7 7 15 15 15 15 15 15 15 15 95 90 85 80 75 70 65 60 Density 0,06 0,12 0,18 0,25 0,32 0,39 0,47 0,55 © ISO 2017 – All rights reserved ISO/TS 19264-1:2017(E) x 199,5 206,5 213,5 220,5 227,5 234,5 241,5 248,5 255,5 262,5 269,5 276,5 Lower horizontal gray scale GS_D_9 GS_D_10 GS_D_11 GS_D_12 GS_D_13 GS_D_14 GS_D_15 GS_D_16 GS_D_17 GS_D_18 GS_D_19 GS_D_20 Numbering Numbers on upper side y 87,5 87,5 87,5 87,5 87,5 87,5 87,5 87,5 87,5 87,5 87,5 87,5 Colour orange Width Height Aimed L* 7 7 7 7 7 7 15 15 15 15 15 15 15 15 15 15 15 15 55 50 45 40 35 30 25 20 15 10 Density 0,64 0,73 0,84 0,95 1,07 1,21 1,36 1,52 1,72 1,95 2,26 D max > 2,3 Typo Verdana 8pt Tolerances for grey scales Tolerances Mean * *