INTERNATIONAL ISO/IEC 14495-2 STANDARD Second edition 2003-04-01 Information technologyLossless and near-lossless compression of continuous-tone still images:Extensions Technologies deIinformation-Compression sansperte etquasi sans perte d'images fixes a modelé continu:Extensions Reference number ISO/IEC 14495-2:2003(E) E @ISO/IEC2003 14495-2:2003(E) ISO/IEC PDF disclaimer This PDF file may contain embedded typefaces.ln accordance with Adobe's licensing policy,this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing.ln downloading this file,parties accept therein the responsibility of not infringing Adobe'slicensing policy.The IsO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be foundin the General Info relative to the file;the PDF-creation parameters were optimized for printing.Every care has been taken to ensure that the file is suitable for use by ISO member bodies.ln the unlikely event that a problem relating to it is found,please inform the Central Secretariat at the address given below. ISO/IEC 2003 Al rights reserved.Unless otherwise specified,no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical,including photocopying and microfim,without permission in writing from either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Case postale 56-CH-1211 Geneva 20 Tel.+41227490111 Fax +41227490947 E-mail [email protected] Web www.iso.org Publishedin Switzerland - @ ISO/IEC 2003-All rights reserved ISO /IEC 14495-2:2003(E) CONTENTS Page 1 Scope 2 Normative references 2.1 Identical Recommendations International Standards 2.2 Additional references .... 3 Definitionsabbreviations, symbols and conventions 3.1 Definitions 3.2 Abbreviations 3.3 Symbol 4 General 4.1 Extensions specified by this Recommendation International Standard 4.1.1 Encoding with arithmetic coding 4.1.2 Extension of near -lossless coding 4.1.3 Extension of prediction ... 4.1.4 Extension of Golomb coding 4.1.5 Fixed length coding ... 4.1.6 Sample transformation for inverse colour transforms 4.2 Descriptions of extended functions 5 Interchange format requirements 6 Encoder requirements 7 Decoder requirements 8 Conformance testing for extensions 8.1 Purpose 8.2 Encoder conformancetests 8.3 Decoder conformance tests Annex A-Encoding procedures with arithmetic coding for a single component 10 A.1 Coding parameters and compressed image data A.2 Initializations and conventions 10 A.2.1 Initializations ... 10 A.2.2 A.3 Context determination ......... A.3.1 Local gradient computation 12 A.3.2 Flat region detection 13 A.3.3 Local gradient quantization A.3.4 Quantized gradient merging A.3.5 Adjustment of error tolerance for near -lossless coding with visual quantization 14 A.4 Prediction A.4.1 Edge -detecting predictor 4 A.4.2 Prediction correction 14 A.4.3 Computation of prediction error 15 A.4.4 Error quantization for near-lossless coding ,and reconstructed value computation A.4.5 Modulo reduction of the prediction error 16 A.5 Prediction error encoding A.5.1 Errormapping 17 A.5.2 Binarization of MErrval with the Golomb code tree 17 A.5.3 Mapped -error encoding A.6 Update variables A.6.1 Update A.6.2 Biascomputation 21 A.7 Flow of encoding procedures 22 @ISOIEC 2003- Allrightsreserved ili