1、Graphic technology and photography Colour characterization of digital still cameras (DSCs)Part 4: Programmable light emission systemPD ISO/TS 17321-4:2016BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06National forewordThis Published Document is the UK implementation
2、 of ISO/TS17321-4:2016. The UK participation in its preparation was entrusted to TechnicalCommittee CPW/42, Photography.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisions ofa contr
3、act. Users are responsible for its correct application. The British Standards Institution 2016.Published by BSI Standards Limited 2016ISBN 978 0 580 90199 7ICS 37.040.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This Published Document was published under the aut
4、hority of theStandards Policy and Strategy Committee on 30 June 2016.Amendments/corrigenda issued since publicationDate Text affectedPUBLISHED DOCUMENTPD ISO/TS 17321-4:2016 ISO 2016Graphic technology and photography Colour characterization of digital still cameras (DSCs) Part 4: Programmable light
5、emission systemTechnologie graphique et photographie Caractrisation de la couleur des appareils photonumriques Partie 4: Systme dmission de lumire programmableTECHNICAL SPECIFICATIONISO/TS17321-4Reference numberISO/TS 17321-4:2016(E)First edition2016-06-01PD ISO/TS 17321-4:2016ISO/TS 17321-4:2016(E)
6、ii ISO 2016 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in SwitzerlandAll 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
7、 on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 74
8、9 09 47copyrightiso.orgwww.iso.orgPD ISO/TS 17321-4:2016ISO/TS 17321-4:2016(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Requirements 24.1 General . 24.2 Hardware requirements 34.2.1 General 34.2.2 Operating condition 44.2.3 Specifications of the system
9、. 44.2.4 Time stability and long-term stability of light intensity 74.3 Figure of merit for a colour target using a programmable light emission system . 94.3.1 General 94.3.2 Terms and notations of SR294.3.3 Method for the calculation of SR2104.3.4 Figure of merit 114.4 Report 11Annex A (informative
10、) Integrating sphere method and LED-driving method 13Annex B (informative) Spectral power distribution optimization procedure for multiple LEDs.15Annex C (informative) The need for constraints on the average values and maximum values of SR2and CIEDE2000 .19Annex D (informative) Evaluation method for
11、 light source generated by a programmable light emission system .21Annex E (informative) SR2and CIEDE2000 recommendations for colorimetric image capture .24Annex F (normative) SR2Land SR2calculation methods for a light emission system in which spectral distribution is only obtained by measurements .
12、26Bibliography .28 ISO 2016 All rights reserved iiiContents PagePD ISO/TS 17321-4:2016ISO/TS 17321-4:2016(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is no
13、rmally 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 organizations, governmental and non-governmental, in liaison with ISO, also take part in
14、 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 further maintenance are described in the ISO/IEC Directives, Part 1. In particular t
15、he 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 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this docu
16、ment 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 Introduction and/or on the ISO list of patent declarations received (see www.iso.or
17、g/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the World
18、Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.The committee responsible for this document is ISO/TC 42, Photography.ISO 17321 consists of the following parts, under the general title Graphic technology and photograph
19、y Colour characterization of digital still cameras (DSCs): Part 1: Stimuli, metrology and test procedures Part 2: Considerations for determining scene analysis transforms Technical Report Part 4: Programmable light emission system Technical SpecificationThe following parts are under preparation: Par
20、t 3: User controls and readouts for scene-referred imaging applications Technical Reportiv ISO 2016 All rights reservedPD ISO/TS 17321-4:2016ISO/TS 17321-4:2016(E)IntroductionThere are many application areas such as medical imaging, cosmetics, e-commerce, sales catalogue, fine art reproduction and a
21、rtistic archive where colorimetric image capture and colorimetric image reproduction are desired.A high colour-fidelity imaging system using a black-and-white digital camera with rotary colour filters12, and digital video cameras specified for colorimetric image capture13, both of which have the sam
22、e colour sensitivity as the colour matching functions defined by CIE 1931, are available today and fulfil these requirements. However, Reference 12 is a large-scale device which cannot be used to capture moving objects, and Reference 13 is dedicated to motion picture use.Digital still cameras (DSCs)
23、 are often used as convenient devices for colorimetric image capture. Typically, DSCs do not have sensor sensitivities that are linear transforms of the colour matching functions defined by CIE 1931. It is, therefore, necessary that a matrix conversion from DSC-image-capture data to scene-colorimetr
24、ic data be done to transform camera image data to estimates of scene colorimetric data. Although there are several methods to derive such a matrix, a method using colour targets is the most common when there is no data describing the DSC sensor spectral sensitivities.Colour targets used to derive th
25、is conversion matrix are X-Rite ColorChecker Classic1), X-Rite ColorChecker Digital SG2)and others. These targets are reflective and so have a limited colour gamut compared to scenes where the subject includes highly saturated colours. In such a case, colour targets with highly saturated colours tha
26、t can be used to derive the colour conversion matrix are very useful.This part of ISO 17321 is applicable to light emitting devices such as inorganic or organic LEDs, quantum dots and laser diodes.Note that although an integrating sphere is typically used, other mechanisms would also be applicable.A
27、 procedure using a nonlinear Generalized Reduced Gradient (GRG) algorithm is specified in this part of ISO 17321 to minimize the square of the difference between a desired colour spectrum and the colour spectrum of the programmable light emission system.This part of ISO 17321 will make use of a metr
28、ic (SR2), which provides a simple and direct means to calculate the colour difference between two spectra. This criterion (SR2) will be used as a method to evaluate the performance of a programmable light emission system in terms of its ability to match a reference spectral power distribution. SR2an
29、d CIEDE2000 metrics are both used for colour target evaluation.This programmable light emission system can generate arbitrary illuminants such as D55, D65 and Illuminant A. Annex D describes evaluation metrics for light sources.This system has several advantages as follows. An arbitrary smooth spect
30、ral power distribution similar to colour targets under a light source can be produced. Many colour metamers can be generated easily. Colours with different luminance, same hue and same saturation can be generated easily. Colours with different saturation, same luminance and same hue can be generated
31、 easily. Colours with high luminance can be produced. Reference colour target can be provided for display systems.1) ColorChecker Classicis an example of a suitable product available commercially. This information is given for the convenience of users of this document and does not constitute an endo
32、rsement by ISO of this product.2) ColorChecker Digital SGis an example of a suitable product available commercially. This information is given for the convenience of users of this document and does not constitute an endorsement by ISO of this product. ISO 2016 All rights reserved vPD ISO/TS 17321-4:
33、2016Graphic technology and photography Colour characterization of digital still cameras (DSCs) Part 4: Programmable light emission system1 ScopeThis part of ISO 17321 specifies requirements for a programmable light emission system to produce various spectral radiance distributions intended for DSC c
34、olour characterization applications.NOTE 1 Evaluation metrics are described in this part of ISO 17321. These evaluations metrics are intended to provide “Figure of Merit (goodness)” relating to the ability of the device to produce arbitrary spectral power distributions.NOTE 2 This part of ISO 17321
35、applies to a programmable light emission system composed of LEDs. However, it can be applied to light emitting devices such as quantum dots, organic LEDs, laser diodes and so forth.NOTE 3 If spiky spectral reproduction is required, devices which have more spiky spectral light emission are intended t
36、o be used.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 the referenced document (including
37、any amendments) applies.ISO 7589, Photography Illuminants for sensitometry Specifications for daylight, incandescent tungsten and printer3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1colour matching functionstristimulus values (3.6) of monochr
38、omatic stimuli of equal radiant powerSOURCE: CIE Publication 17.4, 845-03-233.2colour rendering index Rmeasure of the degree to which the psychophysical colour of an object illuminated by a test illuminant conforms to that of the same object illuminated by the reference illuminant, suitable allowanc
39、e having been made for the state of chromatic adaptationSOURCE: CIE Publication No. 17.4:1987, 845-02-61TECHNICAL SPECIFICATION ISO/TS 17321-4:2016(E) ISO 2016 All rights reserved 1PD ISO/TS 17321-4:2016ISO/TS 17321-4:2016(E)3.3digital still cameraDSCdevice which incorporates an image sensor and whi
40、ch produces a digital signal representing a still pictureNote 1 to entry: A digital still camera is typically a portable, hand-held device. The digital signal is usually recorded on a removable memory, such as a solid-state memory card or magnetic disk.SOURCE: ISO 17321-1:2012, 3.23.4light-emitting
41、diodeLEDsemiconductor diode that emits non coherent optical radiation through stimulated emission resulting from the recombination electrons and photons, when excited by an electric currentSOURCE: IEC 60050-521, 521-04-393.5raw DSC image dataimage data produced by or internal to a DSC that has not b
42、een processed, except for A/D conversion and the following optional steps: linearization, dark current/frame subtraction, shading and sensitivity (flat field) correction, flare removal, white balancing (e.g. so the adopted white produces equal RGB values or no chrominance), missing colour pixel reco
43、nstruction (without colour transformations).SOURCE: ISO 17321-1:2012:3.4 modified.3.6tristimulus valuesamount of the three reference colour stimuli, in a given trichromatic system, required to match the colour of the stimulus consideredNote 1 to entry: See colour matching functions (3.1).SOURCE: CIE
44、 Publication 17.4, 845-03-224 Requirements4.1 GeneralFigure 1 shows a section of an integrating sphere. This sphere is one method to ensure good spatial uniformity. Light emitting devices are placed at the bottom and an output window is placed on the side to allow the mixed light to be emitted. Anne
45、x A shows a typical LED-driving method.NOTE 1 Integrating sphere is a typical case, but other mechanisms would be applicable.There are many kinds of light emitting devices. However, this part of ISO 17321 describes a programmable light emission system using typical LEDs. Figure 2 shows typical spect
46、ral power distributions of a number of LEDs. These LEDs will be intensity-modulated and mixed (integrated) to produce a required spectral power distribution.NOTE 2 Pulse width and interval modulation for intensity modulation is applicable.NOTE 3 DSCs with automatic exposure control and automatic whi
47、te balance cannot be applied for colour calibration using this system.2 ISO 2016 All rights reservedPD ISO/TS 17321-4:2016ISO/TS 17321-4:2016(E)Key1 uniform light emission on the output window2 output window3 light emitting device array4 integrating sphereFigure 1 Schematic configuration of the prog
48、rammable light emission systemFigure 2 Example of spectral power distributions for a chosen set of LEDs4.2 Hardware requirements4.2.1 GeneralThis Clause is to describe a light emitting system for DSC colour characterization that uses an integrating sphere. ISO 2016 All rights reserved 3PD ISO/TS 173
49、21-4:2016ISO/TS 17321-4:2016(E)4.2.2 Operating conditionThe light emitting system shall be designed to operate consistently under the following ranges.NOTE “Temperature” condition was referred from ISO 12646. Temperature: 18 C to 28 C. Relative humidity: 15 % to 80 %.4.2.3 Specifications of the system4.2.3.1 WavelengthThe wavelength range over which the combined set of the light emissive devices is evaluated shall be 380 nm to 730 nm and should be 360 nm to 830 nm.NOTE 1 The
