1、 IEC 61966-2-5 Edition 1.0 2007-11 INTERNATIONAL STANDARD Multimedia systems and equipment Colour measurement and management Part 2-5: Colour management Optional RGB colour space opRGB IEC 61966-2-5:2007(E) THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2007 IEC, Geneva, Switzerland All rights re
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9、L STANDARD Multimedia systems and equipment Colour measurement and management Part 2-5: Colour management Optional RGB colour space opRGB INTERNATIONAL ELECTROTECHNICAL COMMISSION S ICS 17.180.20; 33.160.60 PRICE CODE ISBN 2-8318-9350-X 2 61966-2-5 IEC:2007(E) CONTENTS FOREWORD.3 INTRODUCTION.5 1 Sc
10、ope.6 2 Normative references .6 3 Terms and definitions .6 4 Reference conditions8 4.1 Reference image display system characteristics8 4.2 Reference viewing conditions 8 4.3 Reference observer.9 5 Encoding transformations .9 5.1 Introduction .9 5.2 Transformation from opRGB values to CIE 1931 XYZ va
11、lues.9 5.3 Transformation from CIE 1931 XYZ values to opRGB values.9 Annex A (normative) Transformation between opRGB values and YCC values for image compression.11 Annex B (informative) Example transformation between opRGB values and sYCC values.14 Annex C (informative) Example interpretation for c
12、olour image encoding specifications 19 Bibliography21 Table 1 CIE chromaticities and CIE standard illuminant .8 61966-2-5 IEC:2007(E) 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ MULTIMEDIA SYSTEMS AND EQUIPMENT COLOUR MEASUREMENT AND MANAGEMENT Part 2-5: Colour management Optional RGB colour space
13、 opRGB FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization
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22、drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall
23、not be held responsible for identifying any or all such patent rights. International Standard IEC 61966-2-5 has been prepared by technical area 2: Colour measurement and management, of IEC technical committee 100: Audio, video and multimedia systems and equipment. The text of this standard is based
24、on the following documents: CDV Report on voting 100/1212/CDV 100/1282/RVC Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. 4 61966-
25、2-5 IEC:2007(E) The list of all parts of the IEC 61966 series, under the general title Multimedia systems and equipment Colour measurement and management, can be found on the IEC website. The committee has decided that the contents of this publication will remain unchanged until the maintenance resu
26、lt date indicated on the IEC web site under “http:/webstore.iec.ch“ in the data related to the specific publication. At this date, the publication will be reconfirmed, withdrawn, replaced by a revised edition, or amended. A bilingual version of this publication may be issued at a later date. 61966-2
27、5 IEC:2007(E) 5 INTRODUCTION The colour gamut for various image I/O devices has been gradually extended in recent years. IEC 61966-2-1 “Multimedia Systems and Equipment Colour Measurement and Management Part 2-1: Colour Management Default RGB Colour Space sRGB” is the International Standard issued
28、in 1999, based on the colour characteristics of contemporary CRT displays. Subsequently, displays with a wider colour gamut have been commercialized in order to better cover the colour gamut that is available for digital still cameras, printers and other devices. This International Standard specifie
29、s a colour image encoding similar to the sRGB encoding, but based on a wider gamut colour space than sRGB. The rendering of the image for specific applications is beyond the scope of this standard. A display that has a colour gamut wider than conventional displays has been selected as the “Reference
30、 image display system characteristics” in this standard. These wider colour gamut displays provide advantages in commercial printing industry workflows and are intended to be used by professional photographers, prepress industry including DTP and designers. . 6 61966-2-5 IEC:2007(E) MULTIMEDIA SYSTE
31、MS AND EQUIPMENT COLOUR MEASUREMENT AND MANAGEMENT Part 2-5: Colour management Optional RGB colour space opRGB 1 Scope This part of IEC 61966 is applicable to the encoding and communication of RGB colours optionally used in computer systems and similar applications by defining encoding transformatio
32、ns for use in defined reference conditions. If actual conditions differ from the reference conditions, additional rendering transformations may be required. Such additional rendering transformations are beyond the scope of this standard. 2 Normative references The following referenced documents are
33、indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60050(845):1987, International Electrotechnical Vocabulary (IEV) Chapter 845: Lighti
34、ng / CIE 17.4:1987, International Lighting Vocabulary (Joint IEC/CIE publication) ISO 3664:2000, Viewing conditions Graphic technology and photography ISO/CIE 10527:1991, CIE standard colorimetric observers CIE 15:2004, Colorimetry, 3rd ed. CIE 122:1996, The relationship between digital and colorime
35、tric data for computer-controlled CRT displays CIE 1931, CIE XYZ color space 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. Definitions of colour space, illuminance, luminance, tristimulus and other related lighting terms are provided in IEC 600
36、50(845). 3.1 ambient illuminance level illuminance level due to lighting in the viewing environment, excluding that from the display, measured in the plane of the display faceplate 61966-2-5 IEC:2007(E) 7 3.2 ambient white point coordinate point in the CIE 1931 XYZ chromaticity coordinate defined by
37、 ISO/CIE 10527 and CIE 15.2 due to lighting in the viewing environment, excluding that from the display, measured in the plane of the display faceplate 3.3 display illuminant white point point in the CIE 1931 XYZ chromaticity diagram defined by ISO/CIE 10527 and CIE 15.2, at which the red, green and
38、 blue intensities are at 100 %, measured in a direction perpendicular to the display faceplate 3.4 display background environment of the colour element, extending typically for about ten degrees from the edge of the proximal field in all, or most, directions. When the proximal field is the same colo
39、ur as the background, the latter is regarded as extending from the edge of the colour element considered 3.5 display black level the luminance level characteristic measured in a direction perpendicular to the display faceplate, including unwanted leak light through the faceplate and veiling glare fr
40、om ambient illumination, at which the red, green and blue intensities are at 0 % 3.6 veiling glare light, reflected from an imaging medium, that has not been modulated by the means used to produce the image NOTE In CIE 122, the veiling glare of a CRT display is referred to as ambient flare. 3.7 disp
41、lay model offset parameter measured consistently with CIE 122, representing the black offset level of the display grid voltage 3.8 display input/output characteristic transfer characteristic relating the normalised digital code value and the normalised output luminance as represented by a power func
42、tion 3.9 display luminance level luminance of the display measured consistently with CIE 122 3.10 display surround field outside the background, filling the field of vision 3.11 display proximal field immediate environment of the colour element considered, extending typically for about two degrees f
43、rom the edge of the colour element considered in all, or most, directions 8 61966-2-5 IEC:2007(E) 4 Reference conditions 4.1 Reference image display system characteristics The reference image display system is a computer controlled display and shall be as follows. Display luminance level 160 cd/m 2
44、Display white point = x 0,312 7, = y 0,329 0 (D65) = W X 152,07 = W Y 160,00 = W Z 174,25 Display model offset (R, G and B) 0,0 Display input/output characteristic (R, G and B) 2,2 Display black level 0,4 cd/m 2The CIE chromaticities for the red, green and blue reference display primaries, and for C
45、IE standard illuminant D65, are given in table 1. Table 1 CIE chromaticities and CIE standard illuminant Red Green Blue D65 x 0,640 0 0,210 0 0,150 0 0,312 7 y 0,330 0 0,710 0 0,060 0 0,329 0 z 0,030 0 0,080 0 0,790 0 0,358 3 The reference display characterization is based on the characterization in
46、 CIE 122. Relative to this methodology, the reference display is characterised by the equation below, where opRGB V is the normalised digital count and opRGB Vis the output normalised luminance. () 2 , 2 opRGB opRGB 0 , 0 + = V V (1)4.2 Reference viewing conditions Specifications for the reference v
47、iewing environments are derived from ISO 3664 and shall be as follows: a) Reference background for the background as part of the display screen, the background is 20 % of the reference display luminance level (32 cd/m 2 ); the chromaticity should average to = x 0,312 7, = y 0,329 0 (D65). b) Referen
48、ce surround 20 % diffuse reflectance of the maximum reference ambient illuminance level (4,07 cd/m 2 ); the chromaticity should average to = x 0,345 7, = y 0,358 5 (D50). NOTE This is the luminance of the adapting field. 61966-2-5 IEC:2007(E) 9 c) Reference proximal field 20 % of the reference displ
49、ay luminance level (32 cd/m 2 ); the chromaticity should average to = x 0,312 7, = y 0,329 0 (D65). d) Reference ambient illuminance level 64 lx. e) Reference ambient white point = x 0,345 7, = y 0,358 5 (D50). 4.3 Reference observer The reference observer shall be the CIE 1931 two-degree standard observer from ISO/CIE 10527. 5 Encoding transformations 5.1 Introduction The encoding transformations between CIE 1931 XYZ values and N -bit RGB value
