1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 22028-2:2013Photography and graphictechnology Extended colourencodings for digital imagestorage, manipulation andinterchangePart 2: Reference output medium metricRGB colou
2、r image encoding (ROMM RGB)BS ISO 22028-2:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 22028-2:2013.It supersedes DD ISO/TS 22028-2:2006 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee CPW/42, Photography.A
3、 list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2013. Published by BSI Standards
4、Limited 2013ISBN 978 0 580 76431 8ICS 37.040.99; 37.100.01Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 30 April 2013.Amendments issued since publicationDate Tex
5、t affectedBS ISO 22028-2:2013 ISO 2013Photography and graphic technology Extended colour encodings for digital image storage, manipulation and interchange Part 2: Reference output medium metric RGB colour image encoding (ROMM RGB)Photographie et technologie graphique Codages par couleurs tendues pou
6、r stockage, manipulation et change dimage numrique Partie 2: Codage dimage en couleurs RVB par rfrence de sortie par voie mtriqueINTERNATIONAL STANDARDISO22028-2First edition2013-04-15Reference numberISO 22028-2:2013(E)BS ISO 22028-2:2013ISO 22028-2:2013(E)ii ISO 2013 All rights reservedCOPYRIGHT PR
7、OTECTED DOCUMENT ISO 2013All 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 written permission. Pe
8、rmission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 22028-2:2013ISO 2202
9、8-2:2013(E) ISO 2013 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Requirements 54.1 General . 54.2 Reference viewing environment 54.3 Reference medium . 64.4 ROMM RGB colour image encoding 84.5 Inverse ROMM RGB transform
10、ation 10Annex A (informative) Selection of ROMM RGB colour encoding 13Annex B (informative) Conversion between ROMM RGB and video RGB .17Bibliography .20BS ISO 22028-2:2013ISO 22028-2:2013(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standa
11、rds bodies (ISO member bodies). The work of 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 organ
12、izations, 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 of electrotechnical standardization.The procedures used to develop this document and those intended for its f
13、urther maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directive
14、sAttention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introd
15、uction and/or on the ISO list of patent declarations received. www.iso.org/patentsAny trade name used in this document is information given for the convenience of users and does not constitute an endorsement.The committee responsible for this document is ISO/TC 42, Photography.This first edition can
16、cels and replaces ISO/TS 22028-2:2006, which has been technically revised.ISO 22028 consists of the following parts, under the general title Photography and graphic technology Extended colour encodings for digital image storage, manipulation and interchange: Part 1: Architecture and requirements Par
17、t 2: Reference output medium metric RGB colour image encoding (ROMM RGB) Part 3: Reference input medium metric RGB colour image encoding (RIMM RGB) Technical Specificationiv ISO 2013 All rights reservedBS ISO 22028-2:2013ISO 22028-2:2013(E)IntroductionThis part of ISO 22028 has been developed in ord
18、er to meet the industry need for a complete, fully-documented, publicly-available definition of a wide-primary output-referred extended gamut red-green-blue (RGB) colour image encoding. This colour image encoding provides a way to represent output-referred images that does not limit the colour gamut
19、 to those colours capable of being displayed on typical monitors, as is the case with the sRGB colour encoding, or require the use of negative RGB colourimetry coordinates, as is the case with extended sRGB colour encodings like bg-sRGB.An extended colour-gamut colour encoding is particularly desira
20、ble for professional photography applications. For example, colours used for company logos can be outside a monitor gamut and would therefore need to be clipped or compressed to a less saturated colour. Similarly, photographic prints can contain colours outside a monitor RGB colour gamut. By using a
21、 standard output-referred extended gamut colour image encoding, images containing such colours can be stored, interchanged, manipulated, and later printed, without limiting or distorting the colours of the final output.The Reference output medium metric RGB (ROMM RGB) colour image encoding specified
22、 in this part of ISO 22028 meets the needs of these types of applications. ISO 2013 All rights reserved vBS ISO 22028-2:2013BS ISO 22028-2:2013Photography and graphic technology Extended colour encodings for digital image storage, manipulation and interchange Part 2: Reference output medium metric R
23、GB colour image encoding (ROMM RGB)IMPORTANT The electronic file of this document contains colours which are considered to be useful for the correct understanding of the document. Users should therefore consider printing this document using a colour printer.1 ScopeThis part of ISO 22028 defines a fa
24、mily of extended colour-gamut output-referred RGB colour image encodings designated as reference output medium metric RGB (ROMM RGB). Digital images encoded using ROMM RGB can be manipulated, stored, transmitted, displayed, or printed by digital still picture imaging systems. Three precision levels
25、are defined using 8-, 12- and 16-bits/channel.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of
26、 the referenced document (including any amendments) applies.ISO 15076-1:2010, Image technology colour management Architecture, profile format and data structure Part 1: Based on ICC.1:2010ISO 22028-1:2004, Photography and graphic technology Extended colour encodings for digital image storage, manipu
27、lation and interchange Part 1: Architecture and requirementsISO 11664-1:2007, (CIE S 014-1/E:2006) Colorimetry Part 1: CIE standard colorimetric observers3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1adapted whitecolour stimulus that an observ
28、er who is adapted to the viewing environment would judge to be perfectly achromatic and to have a luminance factor of unity; i.e. absolute colorimetric coordinates that an observer would consider to be a perfect white diffuserNote 1 to entry: The adapted white can vary within a scene.INTERNATIONAL S
29、TANDARD ISO 22028-2:2013(E) ISO 2013 All rights reserved 1BS ISO 22028-2:2013ISO 22028-2:2013(E)3.2additive RGB colour spacecolorimetric colour space having three colour primaries (generally red, green and blue) such that CIE XYZ tristimulus values can be determined from the RGB colour space values
30、by forming a weighted combination of the CIE XYZ tristimulus values for the individual colour primaries, where the weights are proportional to the radiometrically linear colour space values for the corresponding colour primariesNote 1 to entry: A simple linear 3 3 matrix transformation can be used t
31、o transform between CIE XYZ tristimulus values and the radiometrically linear colour space values for an additive RGB colour space.Note 2 to entry: Additive RGB colour spaces are defined by specifying the CIE chromaticity values for a set of additive RGB primaries and a colour space white point, tog
32、ether with a colour component transfer function.3.3colorimetric colour spacecolour space having an exact and simple relationship to CIE colorimetric valuesNote 1 to entry: Colourimetric colour spaces include those defined by CIE (e.g. CIE XYZ, CIELAB, CIELUV), as well as colour spaces that are simpl
33、e transformations of those colour spaces (e.g. additive RGB colour spaces).3.4colour component transfer functionsingle variable, monotonic mathematical function applied individually to one or more colour channels of a colour spaceNote 1 to entry: Colour component transfer functions are frequently us
34、ed to account for the nonlinear response of a reference device and/or to improve the visual uniformity of a colour space.Note 2 to entry: Generally, colour component transfer functions will be nonlinear functions such as a power-law (i.e. “gamma”) function or a logarithmic function. However, in some
35、 cases a linear colour component transfer function can be used.3.5colour encodinggeneric term for a quantized digital encoding of a colour space, encompassing both colour space encodings and colour image encodings3.6colour gamutsolid in a colour space, consisting of all those colours that are either
36、: present in a specific scene, artwork, photograph, photomechanical, or other reproduction; or capable of being created using a particular output device and/or medium3.7colour image encodingdigital encoding of the colour values for a digital image, including the specification of a colour space encod
37、ing, together with any information necessary to properly interpret the colour values such as the image state, the intended image viewing environment and the reference mediumNote 1 to entry: In some cases, the intended image viewing environment will be explicitly defined for the colour image encoding
38、. In other cases, the intended image viewing environment can be specified on an image-by-image basis using metadata associated with the digital image.Note 2 to entry: Some colour image encodings will indicate particular reference medium characteristics, such as a reflection print with a specified de
39、nsity range. In other cases, the reference medium will be not applicable, such as with a scene-referred colour image encoding, or will be specified using image metadata.Note 3 to entry: Colour image encodings are not limited to pictorial digital images that originate from an original scene, but are
40、also applicable to digital images with content such as text, line art, vector graphics and other forms of original artwork.2 ISO 2013 All rights reservedBS ISO 22028-2:2013ISO 22028-2:2013(E)3.8colour renderingmapping of image data representing the colour space coordinates of the elements of a scene
41、 to output-referred image data representing the colour space coordinates of the elements of a reproductionNote 1 to entry: Colour rendering generally consists of one or more of the following: compensating for differences in the input and output viewing conditions; tone scale and gamut mapping to map
42、 the scene colours onto the dynamic range and colour gamut of the reproduction; applying preference adjustments.3.9colour spacegeometric representation of colours in space, usually of three dimensionsCIE Publication 17.4:1987, 845-03-253.10colour space encodingdigital encoding of a colour space, inc
43、luding the specification of a digital encoding method, and a colour space value rangeNote 1 to entry: Multiple colour space encodings can be defined based on a single colour space where the different colour space encodings have different digital encoding methods and/or colour space value ranges. (Fo
44、r example, 8-bit sRGB and 10-bit e-sRGB are different colour space encodings based on a particular RGB colour space.)3.11colour space white pointcolour stimulus to which colour space values are normalizedNote 1 to entry: It is not necessary that the colour space white point correspond to the assumed
45、 adapted white point and/or the reference medium white point for a colour image encoding.3.12continuous colour space valuesreal-valued, unbounded colour space values that have not been encoded using a digital encoding method3.13extended gamutcolour gamut extending outside that of the standard sRGB r
46、eference display as defined by IEC 61966-2-13.14gamut mappingmapping of the colour space coordinates of the elements of a source image to colour space coordinates of the elements of a reproduction to compensate for differences in the source and output medium colour gamut capabilityNote 1 to entry: T
47、he term “gamut mapping” is somewhat more restrictive than the term “colour rendering” because gamut mapping is performed on colourimetry that has already been adjusted to compensate for viewing condition differences and viewer preferences, although these processing operations are frequently combined
48、 in reproduction and preferred reproduction models.3.15ICC profileInternational Color Consortiums file format, used to store transforms from one colour encoding to another, e.g. from device colour coordinates to profile connection space, as part of a colour management system ISO 2013 All rights rese
49、rved 3BS ISO 22028-2:2013ISO 22028-2:2013(E)3.16image stateattribute of a colour image encoding indicating the rendering state of the image dataNote 1 to entry: The primary image states defined in this document are the scene-referred image state, the original-referred image state and the output-referred image state.3.17luminance factorratio of the luminance of the surface element in the given direction to that of a perfect reflecting or transmitting diffuser identically illuminatedCIE Publication 17.4:1987, 845-04-
