ISO INTERNATIONAL STANDARD 20654 First edition 2017-08 Graphic technology Measurement and calculation of spot colour tone value Technologie graphique - Mesurage et calcul de la valeur de tons des couleurs d'accompagnement Reference number IS0 20654:2017(E) ISO @ IS0 2017 IS0 20654:2017(E) COPYRIGHTPROTECTEDDOCUMENT @ IS0 2017, Published in Switzerland All rights reserved. Unless otherwise specified, no part of 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 the requester. ISO copyright office Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax+41227490947 [email protected] www.iso.org ii @ IS0 2017 - All rights reserved IS0 20654:2017(E) Contents Page Foreword ..iv Introduction 1 Scope. 2 Normative references ..1 3 Terms and definitions 1 4 Requirements. .2 4.1 Calculation of spot colour tone value 4.2 Steps for obtaining SCTV from spectral reflectance measurements 4.3 Steps for obtaining SCTV from CIELAB measurements. 3 Bibliography 5 @ IS0 2017 - All rights reserved iii