1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T T.42TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Corrigendum 1(03/2004) SERIES T: TERMINALS FOR TELEMATIC SERVICES Continuous-tone colour representation method for facsimile Corrigendum 1 ITU-T Recommendation T.42 (2003) Corrigendum 1 ITU-T Rec. T.42 (
2、2003)/Cor.1 (03/2004) i ITU-T Recommendation T.42 Continuous-tone colour representation method for facsimile Corrigendum 1 Summary This Recommendation defines a colour data representation method in order to make it possible to interchange continuous-tone colour image data over facsimile communicatio
3、n services such as Group 4 and Group 3 facsimile. This Corrigendum fixes errors in the description of D65 illuminant data and aligns them with ISO 13655. Variables X0, Y0and Z0are changed to “X0= 95.047; Y0= 100.000; Z0= 108.883“ in the Summary, in 6.2.2.2 (White point and illuminant data) and in Ap
4、pendix I (“Method for colorimetric calculation from spectral measurement“). Values of Table I.2/T.42 are replaced with correct values in ISO 13655. CIELAB space is selected as the basic colour space mainly for hard copy (printed) application. CIE Illuminant D50 and its perfectly diffuse reflecting w
5、hite point (X0= 96.422; Y0= 100.000; Z0= 82.521) is selected as the basic illuminant and white point, respectively. The default gamut range chosen is L* = 0, 100, a* = 85, 85, b* = 75, 125. The exact expression is in terms of offset and range. The YCC space based on sYCC is selected also as the basi
6、c colour space mainly for soft copy (displayed) application. CIE illuminant D65 and its perfectly diffuse reflecting white point (X0= 95.047; Y0= 100.000; Z0= 108.883) is the illuminant and white point respectively. The default gamut chosen is Y = 0, 1, Cb = 0.5, 0.5, Cr = 0.5, 0.5. The exact expres
7、sion is in terms of offset and range. The main difference from the previous version is the following: ITU-YCC addition. Source Corrigendum 1 to ITU-T Recommendation T.42 (2003) was approved on 15 March 2004 by ITU-T Study Group 16 (2001-2004) under the ITU-T Recommendation A.8 procedure. ii ITU-T Re
8、c. T.42 (2003)/Cor.1 (03/2004) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, oper
9、ating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, p
10、roduce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In
11、this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. i
12、nteroperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not sugges
13、t that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the eviden
14、ce, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may
15、 be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2004 All rights reserved. No part of this publication may be reproduced, by any means whatsoe
16、ver, without the prior written permission of ITU. ITU-T Rec. T.42 (2003)/Cor.1 (03/2004) iii CONTENTS Page 1) Clause 6.2.2.2 White point and illiminant data . 1 2) Appendix I Method for colorimetric calculation from spectral measurement 1 ITU-T Rec. T.42 (2003)/Cor.1 (03/2004) 1 ITU-T Recommendation
17、 T.42 Continuous-tone colour representation method for facsimile Corrigendum 1 1) Clause 6.2.2.2 White point and illuminant data Replace clause 6.2.2.2 as follows: 6.2.2.2 White point and illuminant data CIE Illuminant D65 and its perfectly diffuse reflecting white point (X0= 95.047; Y0= 100.000; Z0
18、= 108.883) are the basic values. Other illuminants and/or white points are not permitted for ITU-YCC. 2) Appendix I Method for colorimetric calculation from spectral measurement Replace Appendix I as follows: Appendix I Method for colorimetric calculation from spectral measurement The following is a
19、 brief synopsis of the material presented in ISO 13655, Graphic technology Spectral measurement and colorimetric computation for graphic arts images. The data shall be measured from at least 400 nm to at least 700 nm inclusive, at not greater than 20-nm intervals. The reference for spectral data sha
20、ll be based on computed data at 10-nm intervals where the spectral function is triangular with a 10-nm bandwidth at the half-power point. The measurements will be made with a sample mounted on a back backing, as defined by ISO 5, Part 4, subclause 4.7. The reflectance measurement geometry will be 45
21、/0 or 0/45 as defined in ISO 5, Part 4. The measurement resolution shall be to the nearest 0.01% relative to a perfectly diffuse reflector. The tristimulus values of the reference white under D50 illumination will be defined as X0= 96.422; Y0= 100.000 and Z0= 82.521. The spectral weights for illumin
22、ant D50 and 2 observer are given in Table I.1. The tristimulus values of the reference white under D65 illumination will be defined as X0= 95.047; Y0= 100.000; and Z0= 108.883. The spectral weights for illuminant D65 and 2 observer are given in Table I.2. These weights, Wx, Wy and Wz, will be used i
23、n the following manner to derive the tristimulus values: )()( = WxRX summed over ranging from 360 to 780 nm. R is the reflectance value as a function of wavelength (). 2 ITU-T Rec. T.42 (2003)/Cor.1 (03/2004) Table I.1/T.42 Spectral weights (W) for illuminant D50 and 2 observer for calculating trist
24、imulus values at 10-nm intervals Wavelength (nm) W(X) W(Y) W(Z) 360 0.000 0.000 0.001 370 0.001 0.000 0.005 380 0.003 0.000 0.013 390 0.012 0.000 0.057 400 0.060 0.002 0.285 410 0.234 0.006 1.113 420 0.775 0.023 3.723 430 1.610 0.066 7.862 440 2.453 0.162 12.309 450 2.777 0.313 14.647 460 2.500 0.51
25、4 14.346 470 1.717 0.798 11.299 480 0.861 1.239 7.309 490 0.283 1.839 4.128 500 0.040 2.948 2.466 510 0.088 4.632 1.447 520 0.593 6.587 0.736 530 1.590 8.308 0.401 540 2.799 9.197 0.196 550 4.207 9.650 0.085 560 5.657 9.471 0.037 570 7.132 8.902 0.020 580 8.540 8.112 0.015 590 9.255 6.829 0.010 600
26、9.835 5.838 0.007 610 9.469 4.753 0.004 620 8.009 3.573 0.002 630 5.926 2.443 0.001 640 4.171 1.629 0.000 650 2.609 0.984 0.000 660 1.541 0.570 0.000 670 0.855 0.313 0.000 680 0.434 0.158 0.000 690 0.194 0.070 0.000 700 0.097 0.035 0.000 710 0.050 0.018 0.000 720 0.022 0.008 0.000 ITU-T Rec. T.42 (2
27、003)/Cor.1 (03/2004) 3 Table I.1/T.42 Spectral weights (W) for illuminant D50 and 2 observer for calculating tristimulus values at 10-nm intervals Wavelength (nm) W(X) W(Y) W(Z) 730 0.012 0.004 0.000 740 0.006 0.002 0.000 750 0.002 0.001 0.000 760 0.001 0.000 0.000 770 0.001 0.000 0.000 780 0.000 0.
28、000 0.000 Total X = 96.421 Y = 99.997 Z = 82.524 NOTE This table is extracted from ASTM E308 1985. The sums are intended as check-sums for the spectral weights, and are not normative for the white point tristimulus values. Table I.2/T.42 Spectral weights (W) for illuminant D65 and 2 observer for cal
29、culating tristimulus values at 10-nm intervals Wavelength (nm) W(X) W(Y) W(Z) 360 0.000 0.000 0.001 370 0.002 0.000 0.010 380 0.006 0.000 0.026 390 0.022 0.001 0.104 400 0.101 0.003 0.477 410 0.376 0.010 1.788 420 1.200 0.035 5.765 430 2.396 0.098 11.698 440 3.418 0.226 17.150 450 3.699 0.417 19.506
30、 460 3.227 0.664 18.520 470 2.149 0.998 14.137 480 1.042 1.501 8.850 490 0.333 2.164 4.856 500 0.045 3.352 2.802 510 0.098 5.129 1.602 520 0.637 7.076 0.791 530 1.667 8.708 0.420 540 2.884 9.474 0.202 550 4.250 9.752 0.086 560 5.626 9.419 0.037 570 6.988 8.722 0.019 4 ITU-T Rec. T.42 (2003)/Cor.1 (0
31、3/2004) Table I.2/T.42 Spectral weights (W) for illuminant D65 and 2 observer for calculating tristimulus values at 10-nm intervals Wavelength (nm) W(X) W(Y) W(Z) 580 8.214 7.802 0.014 590 8.730 6.442 0.010 600 9.015 5.351 0.007 610 8.492 4.263 0.003 620 7.050 3.145 0.001 630 5.124 2.113 0.000 640 3
32、.516 1.373 0.000 650 2.167 0.818 0.000 660 1.252 0.463 0.000 670 0.678 0.248 0.000 680 0.341 0.124 0.000 690 0.153 0.055 0.000 700 0.076 0.027 0.000 710 0.040 0.014 0.000 720 0.018 0.006 0.000 730 0.009 0.003 0.000 740 0.005 0.002 0.000 750 0.002 0.001 0.000 760 0.001 0.000 0.000 770 0.000 0.000 0.0
33、00 780 0.000 0.000 0.000 Total 95.049 99.999 108.882 NOTE This table is extracted from ASTM E308 1985. The sums are intended as check-sums for the spectral weights, and are not normative for the white point tristimulus values. Printed in Switzerland Geneva, 2004 SERIES OF ITU-T RECOMMENDATIONS Serie
34、s A Organization of the work of ITU-T Series B Means of expression: definitions, symbols, classification Series C General telecommunication statistics Series D General tariff principles Series E Overall network operation, telephone service, service operation and human factors Series F Non-telephone
35、telecommunication services Series G Transmission systems and media, digital systems and networks Series H Audiovisual and multimedia systems Series I Integrated services digital network Series J Cable networks and transmission of television, sound programme and other multimedia signals Series K Prot
36、ection against interference Series L Construction, installation and protection of cables and other elements of outside plant Series M TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits Series N Maintenance: international sou
37、nd programme and television transmission circuits Series O Specifications of measuring equipment Series P Telephone transmission quality, telephone installations, local line networks Series Q Switching and signalling Series R Telegraph transmission Series S Telegraph services terminal equipment Seri
38、es T Terminals for telematic services Series U Telegraph switching Series V Data communication over the telephone network Series X Data networks and open system communications Series Y Global information infrastructure, Internet protocol aspects and Next Generation Networks Series Z Languages and general software aspects for telecommunication systems
