IEC International ISo Standard ISO/IEC 21122-1 Third edition Information technology JPEG 2024-07 Xs low-latency lightweight image coding system - Part 1: Core coding system Technologies de I'information -Systeme de codage d'images legerafaiblelatenceJPEGXS- Partie 1: Systeme de codage de noyau Referencenumber ISO/IEC 21122-1:2024(en) IS0/IEC2024 IS0/IEC21122-1:2024(en) COPYRIGHT PROTECTED DOCUMENT @IS0/IEC2024 All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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 written permission. Permission can be requested from either Iso at the address below or Iso's member body in the country of the requester. ISO copyright office CP 401 : Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone:+41227490111 Email:[email protected] Website: www.iso.org Published in Switzerland @ IS0/IEC 2024 - All rights reserved ii IS0/IEC21122-1:2024(en) Contents Page Foreword. .iv 1 Scope. .1 2 Normativereferences .1 3 Termsand definitions,abbreviatedtermsand symbols .1 3.1 Terms and definitions 3.2 Abbreviatedterms. 6 3.3 Symbols 6 4 Conventions 10 4.1 Conformance language 10 4.2 Operators. .10 4.2.1 Arithmetic operators. 10 4.2.2 Logical operators .10 4.2.3 Relational operators.. .10 4.2.4 Precedenceorderofoperators .10 4.2.5 Mathematical functions .11 5 Functional concepts. 11 5.1 Samplegrid,samplingand components .11 5.2 InterpretationofCFAdata 12 5.3 Wavelet decomposition 12 5.4 Codestream 13 6 Encoderrequirements 13 7 Decoder .13 7.1 Decodingprocessgeneralprovisions 13 7.2 Decoderrequirements 15 AnnexA (normative)Codestream syntax. .16 Annex B (normative)Imagedata structures .32 AnnexC (normative)Entropydecoding .45 .65 AnnexD (normative)Quantization AnnexE(normative)Discretewavelettransformation .70 AnnexF(normative)Multiplecomponenttransformations .80 Annex G (normative) DC level shifting, non-linear transform and output clipping .91 AnnexH (normative)Framebuffer. ..98 AnnexI (informative)Exampleweighttables .106 Bibliography .114 IS0/IEC 2024-All rights reserved iii