1、PD ISO/TR 19263-1:2017 Photography Archiving systems Part 1: Best practices for digital image capture of cultural heritage material BSI Standards Publication WB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06PD ISO/TR 19263-1:2017 PUBLISHED DOCUMENT National foreword This Published Document is
2、 the UK implementation of ISO/TR 19263-1:2017. 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 request to its secretary. This publication does not purport to include all the nec
3、essary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017. Published by BSI Standards Limited 2017 ISBN 978 0 580 95681 2 ICS 01.140.20; 37.040.01 Compliance with a British Standard cannot confer immunity from legal obligations. This B
4、ritish Standard was published under the authority of the Standards Policy and Strategy Committee on 31 March 2017. Amendments/corrigenda issued since publication Date Text affectedPD ISO/TR 19263-1:2017 ISO 2017 Photography Archiving systems Part 1: Best practices for digital image capture of cultur
5、al heritage material Photographie Systmes darchivage Partie 1: Meilleures pratiques pour la capture dimages numriques du matriel de patrimoine culturel TECHNICAL REPORT ISO/TR 19263-1 Reference number ISO/TR 19263-1:2017(E) First edition 2017-03PD ISO/TR 19263-1:2017ISO/TR 19263-1:2017(E)ii ISO 2017
6、 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2017, Published in Switzerland All 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 i
7、nternet 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 office Ch. de Blandonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09
8、 47 copyrightiso.org www.iso.orgPD ISO/TR 19263-1:2017ISO/TR 19263-1:2017(E)Foreword v Introduction vi 1 Scope . 1 2 Analysis of image quality . 1 2.1 General . 1 2.2 Image quality characteristics 1 2.3 ISO 19264 Test chart technical features . 2 2.4 Grid and gray/white features . 2 2.4.1 General 2
9、2.4.2 Running scale features (cm and inches) 3 2.4.3 Grayscale and running gray/white/black bar features 3 2.4.4 Colour patch features . 3 2.4.5 MTF measurement features . 4 2.4.6 Additional ISO 19264 target features/reference data . 4 2.5 Additional targets . 4 2.6 Linear grayscale . 5 2.6.1 DCSG c
10、olour chart . 5 2.6.2 Limitations of Chart Based Imaging System Analysis 5 3 Image quality levels . 6 4 Basic principles of image capture and processing 6 4.1 Overview 6 4.2 Scene referred and output referred image states . 7 4.3 User controls and readouts 7 4.3.1 General 7 4.3.2 Colour Processing C
11、ontrols 7 4.3.3 Exposure readouts . 8 4.3.4 Raw processor readouts and controls . 8 4.3.5 Other user controls 8 4.3.6 Unwanted data modification . 8 4.4 Master images and derivatives 8 4.4.1 General 8 4.4.2 Raw image files 8 4.4.3 Artwork reproduction cycle . 9 5 Imaging system setup and calibration
12、 10 5.1 General 10 5.2 Position camera system 10 5.3 Establish uniformity-even illumination .10 5.3.1 General.10 5.3.2 Optional flat-fielding .10 5.4 Establish exposure 11 5.5 Establish tone reproduction curve (OECF) 11 5.6 Create an ICC colour profile 11 5.7 Analyse colour and tone .12 6 Applicatio
13、n of image quality analysis 12 6.1 Selection of imaging systems: preflighting equipment or vendors 12 6.2 Using ISO 19264 target: Initial system configuration 13 6.3 Using ISO 19264 target: System performance evaluation (benchmarking) .13 6.4 Using ISO 19264 target: Ongoing performance monitoring .1
14、3 7 Technical metadata for image quality analysis .14 Annex A (informative) Linear Grayscale L* to RGB conversion table 15 Annex B (informative) Subjective interpretive imaging (aesthetics) 16 ISO 2017 All rights reserved iii Contents PagePD ISO/TR 19263-1:2017ISO/TR 19263-1:2017(E)Bibliography .19
15、iv ISO 2017 All rights reservedPD ISO/TR 19263-1:2017ISO/TR 19263-1:2017(E) Foreword ISO (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
16、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 work. ISO collaborates clo
17、sely 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 different approval criteria
18、 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 may be the subject of
19、 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/ patents). Any trade n
20、ame 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 conformit y assessment, as well as information about ISOs adherence to the World Trade Organization (
21、WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www . i s o .org/ iso/ foreword .html. The committee responsible for this document is ISO/TC 42, Photography. ISO 2017 All rights reserved vPD ISO/TR 19263-1:2017ISO/TR 19263-1:2017(E) Introduction Today digitization pro
22、grams need to satisfy the demands of an interconnected dynamic user community. A digitized image can be repurposed across any number of systems and therefore needs to be well defined, technically robust and media agnostic. The digital image of an original is intended to satisfy multiple uses includi
23、ng access, archiving, research, conservation, education, marketing, social media, reproduction and distribution both in print and online. Intended for organizations, such as cultural heritage institutions, ISO 19264-1 specifies a method for analysing imaging systems where it is important to control
24、the degree of accuracy and to ensure that imaging quality is maintained over time. There are three common applications of ISO 19264-1: a) imaging system performance evaluation (benchmarking) used for system development and system selection b) imaging system performance optimization used for tailorin
25、g the system to a particular job (use case) c) imaging system performance monitoring used for controlling that the quality of the system remains consistent and within specifications over time The purpose of this document is to provide practical guidance on how to apply ISO 19264-1 for cultural herit
26、age imaging of two-dimensional originals. This includes how the image quality analysis is performed, the function of technical target features, and how to adjust/optimize the performance of imaging systems. Additionally this document illustrates how ISO 19264-1 can be used for selection of appropria
27、te imaging systems and how to establish and maintain image quality in digitization workflows. Annex B provides information related to developing a digitization strategy including assessment of collections, developing a hardware strategy and system selection. ISO 19262 provides definitions for imagin
28、g terminology used in this document and ISO 19264-1.vi ISO 2017 All rights reservedPD ISO/TR 19263-1:2017Photography Archiving systems Part 1: Best practices for digital image capture of cultural heritage material 1 Scope This document specifies how to perform quality analysis of imaging systems (e.
29、g. flatbed scanners, planetary scanners, or digital still cameras) used for digitization of reflective two-dimensional originals. Original materials include but are not limited to books, textual documents, drawings, prints, photographs, and paintings. Certain types of two-dimensional materials with
30、complex surface geometry and or highly reflective surface elements require special illumination techniques that can fall outside the scope of this document. NOTE ISO/TS 19264-2 will address transmissive materials. 2 Analysis of image quality 2.1 General In order to analyse imaging system quality ISO
31、 19264-1 specifies a technical target (ISO 19264-1 target) designed to incorporate multiple technical features for the measurement of key imaging characteristics from a single image. Calculations are performed via software dedicated to ISO 19264-1 target analysis. 2.2 Image quality characteristics I
32、mage technical analysis involves a number of interrelated measurement steps, typically the analysis process begins with validating white balance and tone reproduction followed by additional calculation steps as listed below. When all measurements are within a set of defined tolerances, an imaging sy
33、stem meets a defined quality level. Resolution and geometry are analysed after first analysing core image quality elements. White Balance: adjustment of electronic still picture colour channel gains or image processing so that radiation with relative spectral power distribution equal to that of the
34、scene illumination source is rendered as a visual neutral. Tone Reproduction Curve (TRC): curve graphically describing the relationship between the input tones and the output tones in an imaging process. Gain Modulation (highlights/other patches): variation of the gain over the signal level. Noise:
35、unwanted variations in the response of an imaging system. Dynamic Range: the difference, over a given period of time, between maximum and minimum signal levels, expressed in decibels, contrast ratios or f-stops. Banding: unwanted stripes or bands that occur in a digital image. Defect Pixels: pixel o
36、r subpixel that operates in a way other than the one in which it is driven. TECHNICAL REPORT ISO/TR 19263-1:2017(E) ISO 2017 All rights reserved 1PD ISO/TR 19263-1:2017ISO/TR 19263-1:2017(E) Colour Accuracy: ability of an imaging system to reproduce the colours of some intended object, as specified
37、using some colour difference metric. Sampling Rate (difference between claimed and obtained): number of samples per unit of time, angle, revolutions or other mechanical, independent variable for uniformly sampled data. Resolution (limiting): measure of the ability of a camera system, or a component
38、of a camera system, to depict picture detail. Sharpening: amplification of the SFR by means of image processing to achieve sharper appearing images. Also, a class of image processing operations that enhances the contrast of selective spatial frequencies, usually visually important ones. MTF 50: the
39、modulation transfer function is, a measure of the transfer of modulation (or contrast) from the subject to the image and is used to measure spatial frequency response (SFR). In other words, it measures how faithfully the imaging system reproduces (or transfers) detail from the target to the digital
40、image. MTF50 refers to that spatial frequency (expressed in lines per mm) at which the image retains 50 % of the test targets contrast, see ISO 12233. Illumination non-uniformity (target size related): application of visible radiation (light) to an object. Colour mis-registration: colour-to-colour s
41、patial dislocation of otherwise spatially coincident colour features of an imaged object. Distortion: displacement from the ideal shape of a subject (lying on a plane parallel to the image plane) in the recorded image. Reproduction scale: ratio of the size of an object in a digital image and the siz
42、e of the original object. 2.3 ISO 19264 Test chart technical features The ISO 19264-1 target is defined in ISO 19264-1:, Annex A. Individual chart features are reproduced here to illustrate functionality. An ISO compliant target should contain all of the technical features. Additional targets are ut
43、ilized for characterizing imaging system colour and tone. 2.4 Grid and gray/white features 2.4.1 General Figure 1 Example of grid and gray/white features Gray/white grids are used for analysing illumination non-uniformity and distortion. Illumination non- uniformity is similar to white balance, but
44、applies to illumination at all tonal levels across the entire imaging field and can be adversely affected by the introduction of non-image forming light and or lens falloff. Distortion is often corrected digitally, but doing so recalculates each pixel location in an image, this may negatively influe
45、nce image resolution but may also contribute to an overall improvement in image reproduction accuracy. Illumination-non uniformity results are expressed as L* differences between the maximum and minimum L* values.2 ISO 2017 All rights reservedPD ISO/TR 19263-1:2017ISO/TR 19263-1:2017(E) 2.4.2 Runnin
46、g scale features (cm and inches) Figure 2 Example of running scale Scales are used to determine X and Y resolution, and to test for constant movement (scanners, stitching systems). NOTE This measured function identifies the actual imaged values in both x and y directions, assuring scale integrity of
47、 the images 2.4.3 Grayscale and running gray/white/black bar features Figure 3 Example of grayscale and running gray/white/black bar features The grayscale and running gray/white bars are used to determine OECF (tone recording), gain modulation, noise, and signal to noise ratio Imaging systems shoul
48、d convert the tone values in the original scene to digital values; this technical term is OECF (Opto-Electronic Conversion Function). Validation of the correct selection of these parameters and appropriate representation of the digital information for the selected parameters is a critical function o
49、f image quality analysis. Gain modulation refers to the variation of the gain (distribution of tonal values) over the signal level and is a critical factor in reproduction imaging and colour accuracy. Reported as L*values. The smaller the deviation between the L* of the patches in the reference target and the L* values represented by the digital code values the more accurate the tone reproduction. Noise is generally the digital equivalent of film grain, and presents itself as pixel-to-pixel
