1、 Reference number ISO 16067-1:2003(E) ISO 2003INTERNATIONAL STANDARD ISO 16067-1 First edition 2003-11-15 Photography Spatial resolution measurements of electronic scanners for photographic images Part 1: Scanners for reflective media Photographie Mesurages de rsolution spatiale de scanners lectroni
2、ques pour images photographiques Partie 1: Scanners pour milieux rflchissants ISO 16067-1:2003(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedde
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5、 relating to it is found, please inform the Central Secretariat at the address given below. ISO 2003 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm,
6、 without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2003 Al
7、l rights reservedISO 16067-1:2003(E) ISO 2003 All rights reserved iiiContents Page Foreword iv Introduction v 1 Scope 1 2 Normative references. 1 3 Terms and definitions. 1 4 Test chart. 4 4.1 General. 4 4.2 General characteristics 4 4.3 Test chart elements 6 5 Test conditions 7 5.1 General. 7 5.2 T
8、emperature and relative humidity . 7 5.3 Luminance and colour measurements . 8 5.4 Linearization 8 5.5 Scanner settings. 8 6 Measuring the scanner OECF 8 7 Limiting visual resolution and its relation to SFR . 8 8 Edge SFR test measurement . 9 9 Presentation of results . 9 9.1 General. 9 9.2 Scanner
9、OECF. 10 9.3 Resolution measurements. 11 Annex A (normative) Scanner OECF Test Patches. 13 Annex B (normative) SFR algorithm. 14 Annex C (informative) Using slanted edge analysis for colour spatial registration measurement . 17 Bibliography . 19 ISO 16067-1:2003(E) iv ISO 2003 All rights reservedFor
10、eword 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 technical committees. Each member body interested in a subject for which a tech
11、nical 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 matters of
12、 electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated t
13、o the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. 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
14、 identifying any or all such patent rights. ISO 16067-1 was prepared by Technical Committee ISO/TC 42, Photography. ISO 16067 consists of the following parts, under the general title Photography Spatial resolution measurements of electronic scanners for photographic images: Part 1: Scanners for refl
15、ective media Part 2: Film scanners ISO 16067-1:2003(E) ISO 2003 All rights reserved vIntroduction One of the most important characteristics of an electronic print scanner is the ability to capture the fine detail found in the original print. This ability to resolve detail is determined by a number o
16、f factors, including the performance of the scanner lens, the number of addressable photoelements in the image sensor(s) used in the scanner, and the electrical circuits in the scanner. Different measurement methods can yield different metrics that quantify the ability of the scanner to capture fine
17、 details. This part of ISO 16067 specifies methods for measuring the limiting visual resolution and spatial frequency response calculated from a slanted edge (Edge SFR) imaged by a print scanner. The scanner measurements described in this part of ISO 16067 are performed in the digital domain, using
18、digital analysis techniques. A test chart of appropriate size and characteristics is scanned and the resulting data analysed. The test chart described in this part of ISO 16067 is designed specifically for the evaluation of continuous tone print scanners. It is not designed for evaluating electronic
19、 still picture cameras, video cameras or bi-tonal document scanners. The edge SFR measurement method described in this part of ISO 16067 uses a computer algorithm to analyse digital image data from the print scanner. Pixel values near slanted vertical and horizontal edges are used to compute the SFR
20、 values. The use of a slanted edge allows the edge gradient to be measured at many phases relative to the image sensor photoelements, so that the SFR can be determined at spatial frequencies higher than the half-sampling frequency, sometimes called the Nyquist limit. This technique is mathematically
21、 equivalent to a moving knife edge measurement. INTERNATIONAL STANDARD ISO 16067-1:2003(E) ISO 2003 All rights reserved 1Photography Spatial resolution measurements of electronic scanners for photographic images Part 1: Scanners for reflective media 1 Scope This part of ISO 16067 specifies methods f
22、or measuring and reporting the spatial resolution of electronic scanners for continuous tone photographic prints. It is applicable to both monochrome and colour print scanners. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated
23、 references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 5 (all parts), Photography Density measurements ISO 554, Standard atmospheres for conditioning and/or testing Specifications ISO 12231, Photograp
24、hy Electronic still-picture cameras Terminology ISO 14524:1999, Photography Electronic still-picture cameras Methods for measuring opto-electronic conversion functions (OECFs) 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 12231 and the following ap
25、ply. 3.1 addressable photoelements number of active photoelements in an image sensor equal to the number of active lines of photoelements, multiplied by the number of active photoelements per line 3.2 aliasing output image artefacts that occur in a sampled imaging system for input images having sign
26、ificant energy at frequencies higher than the Nyquist frequency of the system NOTE These artefacts usually manifest themselves as moir patterns in repetitive image features or as jagged “stairstepping” at edge transitions. ISO 16067-1:2003(E) 2 ISO 2003 All rights reserved3.3 digital output level di
27、gital code value numerical value assigned to a particular output level 3.4 edge spread function ESF normalized spatial signal distribution in the linearized output of an imaging system resulting from imaging a theoretical infinitely sharp edge 3.5 effectively spectrally neutral having spectral chara
28、cteristics which result in a specific imaging system producing the same output as for a spectrally neutral object 3.6 electronic scanners for photographic prints scanner incorporating an image sensor that outputs a digital signal representing a still print image 3.7 fast scan direction scan directio
29、n corresponding to the direction of the alignment of the addressable photoelements in a linear array image sensor 3.8 gamma correction signal processing operation that changes the relative signal levels in order to adjust the image tone reproduction NOTE 1 Gamma correction is performed in part to co
30、rrect for the nonlinear light-output versus signal input characteristic of the display. The relationship between the light input level and the output signal level, called the OECF, provides the gamma correction curveshape for an image capture device. NOTE 2 The gamma correction is usually an algorit
31、hm, look-up table or circuit which operates separately on each colour component of an image. 3.9 image sensor electronic device that converts incident electromagnetic radiation into an electronic signal EXAMPLE Charge-coupled device (CCD) array. 3.10 resolution measure of the ability of a digital im
32、age capture system, or a component of a digital image capture system, to depict spatial picture detail NOTE Resolution measurement metrics include resolving power, limiting visual resolution, SFR, MTF and CTF. 3.11 sampled imaging system imaging system or device which generates an image signal by sa
33、mpling an image at an array of discrete points, or along a set of discrete lines, rather than a continuum of points NOTE The sampling at each point is done using a finite-size sampling aperture or area. 3.12 sample spacing physical distance between sampling points or sampling lines ISO 16067-1:2003(
34、E) ISO 2003 All rights reserved 3NOTE 1 The sample spacing may be different in the two orthogonal sampling directions. NOTE 2 It is measured in units of distance (e.g. micrometres, millimetres). 3.13 sampling frequency reciprocal of sample spacing NOTE It is expressed in samples per unit distance e.
35、g. dots per inch (DPI) 3.14 scanner electronic device that converts a fixed image, such as a print or film transparency, into an electronic signal 3.15 scanner opto-electronic conversion function scanner OECF relationship between the input density and the digital output levels for an opto-electronic
36、 digital capture system 3.16 slow scan direction direction in which the scanner moves the photoelements (perpendicular to the lines of active photoelements in a linear array image sensor) 3.17 spatial frequency response SFR measured amplitude response of an imaging system as a function of relative i
37、nput spatial frequency NOTE The SFR is normally represented by a curve of the output response to an input sinusoidal spatial luminance distribution of unit amplitude, over a range of spatial frequencies, and is normalized to yield a value of 1,0 at a spatial frequency of 0. 3.18 spectrally neutral e
38、xhibiting reflective or transmissive characteristics which are constant over the wavelength range of interest 3.19 test chart arrangement of test patterns designed to test particular aspects of an imaging system 3.20 test pattern specified arrangement of spectral reflectance or transmittance charact
39、eristics used in measuring an image quality attribute NOTE The test pattern spectral characteristics include the types given in 3.21.1 to 3.21.3. 3.20.1 bitonal patterns pattern that is spectrally neutral or effectively spectrally neutral, and which consists exclusively of two reflectance or transmi
40、ttance values in a prescribed spatial arrangement NOTE Bitonal patterns are typically used to measure resolving power, limiting resolution and SFR. ISO 16067-1:2003(E) 4 ISO 2003 All rights reserved3.20.2 grey-scale patterns pattern that is spectrally neutral or effectively spectrally neutral, and w
41、hich consists of a large number of different reflectance or transmittance values in a prescribed spatial arrangement NOTE Grey-scale patterns are typically used to measure opto-electronic conversion functions. 3.20.3 spectral pattern pattern that is specified by the spatial arrangement of features w
42、ith differing spectral reflectance or transmittance values NOTE Spectral patterns are typically used to measure colour reproduction. 4 Test chart 4.1 General This clause defines the type and specifications of the test chart depicted in Figure 1. The test chart can be made in various sizes to corresp
43、ond to popular print sizes. Figure 1 Representation of test chart 4.2 General characteristics 4.2.1 The test chart shall be a reflection test chart based on current monochrome photographic print material. The print material shall be spectrally neutral with tolerances as specified in ISO 14524, and s
44、hall be resistant to fading. 4.2.2 The active height and width of the reflection test chart should be no less than 100 mm. Additional white space may be added to the width or height to include target management data or other test chart elements not defined by this part of ISO 16067. ISO 16067-1:2003
45、(E) ISO 2003 All rights reserved 54.2.3 The test chart shall include grey-scale patterns and should include bitonal elements. Grey-scale patches are necessary to measure the opto-electronic transfer function of the scanner. The bitonal elements may be used to assess limiting visual resolution and al
46、iasing. (See Clause 7.) 4.2.4 The density values of the grey patches shall be in accordance with Annex A. The densities shall be measured as specified in ISO 5. 4.2.5 The target manufacturer should state the spatial frequency at which the targets frequency content is 0,2. These declarations should b
47、e cited in both cycles per millimetre (cycles/mm) and equivalent dots-per-inch (DPI), where the DPI value equals 50,8 times the spatial frequency in cycles per millimetre. Suggested wording is, “This target suitable for SFR measurements to XXX cycles per millimetre (xxxx dpi)”. The spatial frequency
48、 content of the edge features should be the same for both near-horizontal, near-vertical, and near-45 edge features, and should be indicated as a graph (Figure 2), or should be characterized with a closed form equation or equations up to the frequency having a 0,2 modulation response. NOTE An exampl
49、e equation corresponding to Figure 2 is the n-th order polynomial: Target modulation = C 0+ C 1 1+ C 2 2+ C 3 3+ C 4 4+ C 5 5+ C 6 6+ C 7 7(1) where is the spatial frequency in terms of line pairs per millimetre; C iare the polynomial coefficients associated with the ith term C 0= 1,000 0e + 00 C 1= 1,016 1e 02 C 2= 5,938 9e 03 C 3= 5,611 6e 04 C 4= 2,344 3e 05 C 5= 5,099 7e 07 C 6= 5,612 0e 09 C 7= 2,468 1e 11 X spatial frequency (in cycles per millimetre) Y modulation Fig
