1、Photography Digital cameras Image flare measurementBS ISO 18844:2017BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06 ISO 2017Photography Digital cameras Image flare measurementPhotographie Camras numriques Mesurage de lclat dimageINTERNATIONAL STANDARDISO18844First e
2、dition2017-05Reference numberISO 18844:2017(E)National forewordThis British Standard is the UK implementation of ISO 18844:2017.The UK participation in its preparation was entrusted to Technical Committee CPW/42, Photography.A list of organizations represented on this committee can be obtained on re
3、quest to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017 Published by BSI Standards Limited 2017ISBN 978 0 580 83272 7ICS 37.040.10Compliance with a Britis
4、h Standard cannot confer immunity from legal obligations. This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2017.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDBS ISO 18844:2017 ISO 2017Photography Digit
5、al cameras Image flare measurementPhotographie Camras numriques Mesurage de lclat dimageINTERNATIONAL STANDARDISO18844First edition2017-05Reference numberISO 18844:2017(E)BS ISO 18844:2017ISO 18844:2017(E)ii ISO 2017 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2017, Published in SwitzerlandA
6、ll 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. Permission can be requested
7、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 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 18844:2017ISO 18844:2017(E)ii ISO 2017 All rights rese
8、rvedCOPYRIGHT PROTECTED DOCUMENT ISO 2017, 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 on the internet or an intr
9、anet, 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 22 749 09 47copyrightiso.orgwww.
10、iso.orgISO 18844:2017(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Measurement chart and method . 24.1 Conditions of shooting . 24.1.1 Arrangement of measuring equipment 24.1.2 Conditions of shooting 34.2 Charts 34.2.1 General 34.2.2 Charts for single sp
11、ot measurement . 44.2.3 Charts for multiple spot measurement 44.3 Measurement procedure 54.3.1 General 54.3.2 Calculation of luma and luminance 54.3.3 Areas used for calculation of luma and luminance 64.3.4 Measurement types . 75 Presentation of results . 9Annex A (informative) Examples of reporting
12、 .11Bibliography .12 ISO 2017 All rights reserved iiiContents PageBS ISO 18844:2017ISO 18844:2017(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 normally c
13、arried 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 the wor
14、k. 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 the diffe
15、rent 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 document
16、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 .org/
17、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 voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information a
18、bout ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www .iso .org/ iso/ foreword .html.This document was prepared by Technical Committee ISO/TC 42, Photography.iv ISO 2017 All rights reservedBS ISO 18844:2017ISO 18844:2
19、017(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 normally carried out through ISO technical committees. Each member body interested in a subject for whic
20、h 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 the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all ma
21、tters 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 the different approval criteria needed for the different types of ISO documents should be noted. This d
22、ocument 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 document may be the subject of patent rights. ISO shall not be held responsible for identifying any or
23、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 .org/ patents).Any trade name used in this document is information given for the convenience of user
24、s and does not constitute an endorsement.For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers
25、 to Trade (TBT) see the following URL: www .iso .org/ iso/ foreword .html.This document was prepared by Technical Committee ISO/TC 42, Photography.iv ISO 2017 All rights reserved ISO 18844:2017(E)IntroductionWhen images are produced by a digital camera, the camera captures not only the light from th
26、e scene but also stray, unwanted light (flare) that can reduce contrast in the image. Generally, the processing applied to the image will compensate for normal amounts of flare light, resulting in improved image quality. However, flare light can be quite variable, and image processing algorithms are
27、 not always successful at removing it. Poor or excessive flare removal processing can reduce the quality of the final image. For example, subtraction of the average flare across the image could result in over-subtraction of the flare in dark areas, resulting in loss of shadow detail. In evaluating d
28、igital cameras, it is therefore useful to measure the signal from the flare light remaining in processed images. This remaining flare signal is called “image flare.”Image flare in digital cameras is caused not only by lenses but also by camera bodies and image sensors, and is affected by image proce
29、ssing. Measurements of image flare include all contributing factors: the optical system, camera body, image sensor, and image processing. ISO 9358 specifies methods of measuring “veiling glare,” the flare from lens systems, but it is not intended to be applied for the measurement of image flare. Thi
30、s document specifies a method to measure image flare using the image data output by digital cameras.A standard method is needed in part because of the nature of image flare. It can vary both locally and from image to image depending on all the factors mentioned above. While it is possible to measure
31、 image flare at different positions in different images, the variability of image flare makes it difficult to compare such measurements out of context. This document provides a standard method for measuring image flare which can be useful for cross comparison. ISO 2017 All rights reserved vBS ISO 18
32、844:2017BS ISO 18844:2017Photography Digital cameras Image flare measurement1 ScopeThis document specifies the definition of image flare for digital cameras, test patterns, measurement conditions, and methods, so as to enable the comparison of the results of measurement.The methods of measurement ar
33、e designed to enable the assessment of the performance of digital cameras by using image data output by the digital cameras.This document does not specify the aim values or the allowable range of value for the image flare.2 Normative referencesThe following documents are referred to in the text in s
34、uch a way that some or all of their content constitutes requirements 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 61966-2-1, Multimedia systems and equipment Colour
35、 measurement and management Part 2-1: Default RGB colour space sRGB3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at h
36、 t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t t p :/ www .iso .org/ obp3.1image flareunwanted increase in signal in a processed image output by a digital camera resulting from light detected by an image sensor that does not emanate from a corresponding subject poin
37、tNote 1 to entry: Image flare is measured for a camera system. The camera system includes lenses, camera body, image sensor, and image processing used for the measurement. The following four are common with regard to light detection: i) internal multiple reflections, scattering or diffraction of opt
38、ics (including lens surfaces, filter surfaces, or sensors), ii) light diffusion at lens barrel, body, or edge of lens, iii) leaking of light, and iv) the optical system as measured by point spread function including spherical and chromatic aberrations. Differentiation between these four might be dif
39、ficult once an image is captured, but it is more appropriate to isolate the last one with regard to the system resolution. Thus, care should be taken to minimize point spread function contribution in the measurement of image flare. Image flare also includes the effects of image processing. Even if t
40、he same camera is used to capture RAW image data, different image flare values might be measured if different image processing algorithms are applied. This is an intended result because the measurement of image flare includes all contributing factors of lenses, camera body, image sensor, and image p
41、rocessing.Note 2 to entry: “Image flare” was defined in ISO 3664:2000 in another context, but it was deleted in ISO 3664:2009.Note 3 to entry: “Image flare” is defined in ISO 12231:2012 but without any source standards. The definition is the same statement as in ISO 3664:2000. ISO 3664:2000 was repl
42、aced by ISO 3664:2009 and this does not include the definition of “image flare.”INTERNATIONAL STANDARD ISO 18844:2017(E) ISO 2017 All rights reserved 1BS ISO 18844:2017ISO 18844:2017(E)4 Measurement chart and method4.1 Conditions of shootingEach test chart shall be specified together with the lighti
43、ng conditions such as illuminance, luminance, and colour temperature of illumination.4.1.1 Arrangement of measuring equipment4.1.1.1 Reflection-type test chartThe arrangement of the measuring equipment for a reflection-type test chart shall be set up as shown in Figure 1. The light source(s) should
44、be positioned to provide uniform illumination and produce no glare or specular reflections from the target.Matte black wall or black surround Test chart Lamp Lamp Digital camera Distance is adjusted to frame the test chart Bafg976les to prevent direct illumination of the camera lens by the lamps Fig
45、ure 1 Arrangement of measuring equipment for reflection-type test chart4.1.1.2 Transparent-type test chartThe arrangement of the measuring equipment for a transparent-type test chart shall be set up as shown in Figure 2.2 ISO 2017 All rights reservedBS ISO 18844:2017ISO 18844:2017(E)4 Measurement ch
46、art and method4.1 Conditions of shootingEach test chart shall be specified together with the lighting conditions such as illuminance, luminance, and colour temperature of illumination.4.1.1 Arrangement of measuring equipment4.1.1.1 Reflection-type test chartThe arrangement of the measuring equipment
47、 for a reflection-type test chart shall be set up as shown in Figure 1. The light source(s) should be positioned to provide uniform illumination and produce no glare or specular reflections from the target.Matte black wall or black surround Test chart Lamp Lamp Digital camera Distance is adjusted to
48、 frame the test chart Bafg976les to prevent direct illumination of the camera lens by the lamps Figure 1 Arrangement of measuring equipment for reflection-type test chart4.1.1.2 Transparent-type test chartThe arrangement of the measuring equipment for a transparent-type test chart shall be set up as
49、 shown in Figure 2.2 ISO 2017 All rights reserved ISO 18844:2017(E)Distance is adjustedto frame the test chartTest chartLighting boxDigital stillcameraMatte black wall or black surroundFigure 2 Arrangement of measuring equipment for transparent-type test chart4.1.2 Conditions of shootingUnless otherwise stated, the conditions of shooting are as follows.a) Illuminance of illumination of a reflection-type test chart should be 1 000 lx to 2 000 lx.b) Luminance of transparent-type lighting box shoul
