SIST ISO 16067-1:2011

Photography - Spatial resolution measurements of electronic scanners for photographic images -- Part 1: Scanners for reflective media

This part of ISO 16067 specifies methods for measuring and reporting the spatial resolution of electronic scanners for continuous tone photographic prints. It is applicable to both monochrome and colour print scanners.

Photographie - Mesurages de résolution spatiale de scanners électroniques pour images photographiques -- Partie 1: Scanners pour milieux réfléchissants

Fotografija - Meritve prostorske ločljivosti elektronskih skenerjev za fotografske slike - 1. del: Skenerji za refleksijske medije

Ta del ISO 16067 določa metode za merjenje in poročanje o prostorski ločljivosti elektronskih skenerjev za fotografske natise z neprekinjenim tonom. Velja za skenerje za črno-beli in barvni tisk.

General Information

• Status: Published
• Publication Date: 09-Jun-2011
• ICS: 37.040.10 - Photographic equipment. Projectors
• Technical Committee: GRT - Graphical technology
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 02-Jun-2011
• Due Date: 07-Aug-2011
• Completion Date: 10-Jun-2011
• Ref Project: ISO 16067-1:2003 - Photography — Spatial resolution measurements of electronic scanners for photographic images — Part 1: Scanners for reflective media

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 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 résolution spatiale de scanners
électroniques pour images photographiques —
Partie 1: Scanners pour milieux réfléchissants




Reference number
ISO 16067-1:2003(E)
©
ISO 2003

---------------------- Page: 1 ----------------------
ISO 16067-1:2003(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem 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, without permission in writing from either ISO at the address below or
ISO's 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 [e-mail]
Web www.iso.org
Published in Switzerland

ii © ISO 2003 — All rights reserved

---------------------- Page: 2 ----------------------
ISO 16067-1:2003(E)
Contents 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 Temperature 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 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

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ISO 16067-1:2003(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
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 closely with the
International Electrotechnical Commission (IEC) on all matters of 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 to 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 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 reflective media
 Part 2: Film scanners
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ISO 16067-1:2003(E)
Introduction
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 of 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 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 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 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 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 equivalent to a moving knife edge measurement.


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INTERNATIONAL STANDARD ISO 16067-1:2003(E)

Photography — Spatial resolution measurements of electronic
scanners for photographic images —
Part 1:
Scanners for reflective media
1 Scope
This part of ISO 16067 specifies methods for 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
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, Photography — 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 apply.
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 significant energy at
frequencies higher than the Nyquist frequency of the system
NOTE These artefacts usually manifest themselves as moiré patterns in repetitive image features or as jagged
“stairstepping” at edge transitions.
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ISO 16067-1:2003(E)
3.3
digital output level
digital 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 characteristics 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 direction 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 correct 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 algorithm, 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 image 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 sampling 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
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ISO 16067-1:2003(E)
NOTE 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.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 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 input 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
exhibiting 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 characteristics 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 transmittance values in a prescribed spatial arrangement
NOTE Bitonal patterns are typically used to measure resolving power, limiting resolution and SFR.
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ISO 16067-1:2003(E)
3.20.2
grey-scale patterns
pattern that is spectrally neutral or effectively spectrally neutral, and which 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 with 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 correspond 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 shall 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.
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ISO 16067-1:2003(E)
4.2.3 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 aliasing. (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 target's frequency content is
0,2. These declarations should be 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 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 example equation corresponding to Figure 2 is the n-th order polynomial:
1 2 3 4 5 6 7
Target modulation = C + C ν + C ν + C ν + C ν + C ν + C ν + C ν (1)
0 1 2 3 4 5 6 7
where
ν is the spatial frequency in terms of line pairs per millimetre;
C are the polynomial coefficients associated with the ith term
i
C = 1,000 0e + 00 C = − 1,016 1e − 02 C = − 5,938 9e − 03 C = 5,611 6e − 04
0 1 2 3
C = − 2,344 3e − 05 C = 5,099 7e − 07 C = − 5,612 0e − 09 C = 2,468 1e − 11
4 5 6 7

X spatial frequency (in cycles per millimetre)
Y modulation
Figure 2 — Example of the frequency content of a reflection edge's spatial derivative
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ISO 16067-1:2003(E)
4.3 Test chart elements
4.3.1 General
For testing purposes, the test chart (Figure 3) shall include elements for measuring the scanner opto-
electronic conversion function and SFR in the fast-scan and slow-scan directions.

Figure 3 — Test chart elements (see subclauses indicated and Figure 1)
4.3.2 Grey-scale patches
The test chart shall include twenty neutral grey-scale patches with specified visual densities for measuring the
scanner OECF. The maximum patch reflection density shall be at least 1,5 times the maximum density of the
central slanted square (see 4.3.3). The minimum patch density shall be equal to the reflective media minimum
density. The spatial arrangement of the patches shall be designed to minimize flare between adjacent patches
as depicted in Figure 1. A suggested spatial arrangement is given in Annex A.
4.3.3 Near-vertical and near-horizontal slanted edges
The test chart shall include a slanted (approximately 5°) square feature used to measure vertical- and
horizontal-edge SFR. The density of the square shall exceed that of the immediate surrounding area. The
central square's surround density shall have a visual diffuse density of W 0,40 and u 0,60. The square patch
density shall have a visual diffuse density of W 1,00 and u 1,20.
NOTE These values ensure sufficiently low edge transition contrasts to facilitate robust SFR measurements.
4.3.4 Near-45° edges
The test chart should include a diamond-shaped feature (approximately 50° from vertical) for measuring the
SFR at 45°. The density of this feature should match that of the surround area defined in 4.3.3.
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ISO 16067-1:2003(E)
4.3.5 Vertical and horizontal square wave features
The test chart should include horizontal and vertical square wave features of extended length to aid in the
visual detection of aliasing. These features shall have a spatial frequency of 6 cycles/mm, 8 cycles/mm,
12 cycles/mm, 24 cycles/mm and 40 cycles/mm. The minimum and maximum densities should nominally
match the D and D of the grey-scale patches.
max min
NOTE The square wave features have a spatial frequency corresponding to approximately 300 DPI, 400 DPI,
600 DPI, 1 200 DPI and 2 000 DPI.
4.3.6 Near-vertical and near-horizontal square features
The test chart should include horizontal and vertical square wave features of extended length to aid in the
detection of aliasing. These features shall have the same frequencies as indicated in 4.3.8. The minimum and
maximum densities should nominally match the D and D of the grey-scale patches.
max min
NOTE These slanted lines eliminate the ambiguity of phase induced patterns in resolution measurements.
4.3.7 Fiducial marks
The test chart should include fiducial marks in the corners of the central target features. These marks can aid
in the automatic analysis of grey patch and slanted edge features for scanner OECF and SFR measurements.
NOTE The vertical and horizontal distance between fiducial marks in Figure 1 is 50,8 mm. This distance can be used
to verify scanner sampling frequency.
4.3.8 Slightly slanted extended lines
The test chart should include horizontal and vertical, slightly slanted lines for the checking of scan linearity,
“stairstepping” and cyclical scanner behaviours such as colour channel misregistration.
4.3.9 Bitonal spatial resolution elements
The test chart should include bitonal spatial patterns to aid in evaluating limiting visual resolution. These
elements should be of high contrast (D and D ) and accompanied by numbered groups keyed for
max min
recognition of spatial frequencies.
4.3.10 Administrative elements
The test chart should include administrative elements to aid in tracking the genealogy and characteristics of
the test chart being used. These may be items such as manufacturer's insignia, creation date or barcode.
5 Test conditions
5.1 General
The following measurement conditions should be used as nominal conditions when measuring the scanner
OECF and spatial resolution. If it is not possible or appropriate to achieve these nominal operating conditions,
the actual operating conditions shall be listed along with the reported results.
5.2 Temperature and relative humidity
The ambient temperature during the acquisition of the test data shall be (23 ± 2) °C, as specified in ISO 554,
and the relative humidity should be (50 ± 20) %.
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ISO 16067-1:2003(E)
5.3 Luminance and colour measurements
For a colour scanner, the spatial resolution measurements should be performed on each colour record
separately. If desired, a luminance resolution measurement may be made on a luminance signal formed from
an appropriate combination of the colour records. In either case, the channel on which the measurement is
performed shall be reported.
5.4 Linearization
The scanner output signal will likely be a non-linear function of the print density values. Linearization is
accomplished by applying the inverse of the scanner OECF to the output signal via a lookup table or
appropriate equation and then converting from density to reflectance. The measurement of the scanner OECF
shall be as specified in Clause 6.
5.5 Scanner settings
The spatial resolution should be measured with the manufacturer's recommended default settings. If different
settings are used, they shall be reported.
6 Measuring the scanner OECF
The scanner OECF shall be calculated from values determined from the same chart and scan as the values
for the resolution measurements. Many scanners will automatically adapt to the dynamic range and the
luminance distribution of the print. The results may also differ if the scan mode is grey scale or RGB.
A minimum of four trials shall be conducted for each resolution measurement and scanner OECF
determination. A trial shall consist of one scan of the test chart. For each trial, the digital output level shall be
determined from a 64 pixel by 64 pixel area located at the same relative position in each patch. It is possible
that with very low resolution scans the images of the test chart patches will not be large enough to contain a
64 pixel by 64 pixel area. In this case, the sample area should be slightly smaller than the image of the patch
area so that the effects of imaging the patch edge are not included.
Identical, non-aligned patches may be averaged, or the patch with the least scanning artefacts, such as dust
or scan lines, may be used. The scanner OECF so determined shall be used to calculate the resolution
measurements for this trial. If the scanner OECF is reported, the final digital output level data presented for
each step density shall be the mean of the digital output levels for all the trials.
7 Limiting visual resolution and its relation to SFR
To determine the limiting visual resolution, the image of the test target is reproduced on a monitor or
hard-copy print, and the visual resolution is subjectively judged. To ensure that the monitor or hard-copy
printer does not reduce the visual resolution value, the digital image may be enlarged by pixel replication prior
to viewing or printing, so that the individual pixels are visible. Observers should be well acquainted with the
appearance of aliasing, so that they do not seriously misjudge the visual resolution of the scanner. The test
chart includes vertical and horizontal elements that are used to perform this test. The limiting visual resolution
is the lowest value of the test pattern where the individual black and white lines can no longer be
distinguished, or are reproduced at a spatial frequency lower than the spatial frequency of the corresponding
area of the test chart, as a result of aliasing. The limiting visual resolution value shall not exceed the
half-sampling frequency. Should this frequency exceed the half-sampling frequency, the limiting visual
resolution shall be the spatial frequency associated with the half-sampling frequency. The limiting visual
resolution in the fast scan direction is normally determined by observing the vertical elements. The visual
resolution in the slow scan direction is normally determined by observing the horizontal elements.
A very good correlation between limiting visual resolution and the spatial frequency associated with a
0,10 SFR response has been found experimentally. Should this frequency exceed the half-sampling
frequency, the limiting visual resolution shall be the spatial frequency associated with the half-sampling
frequency.
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ISO 16067-1:2003(E)
8 Edge SFR test measurement
The spatial frequency response (SFR) of a print scanner is measured by analysing the scanner data near a
slanted edge transition. The near vertical edges shown in Figure 1 are normally used to measure the SFR in
the fast scan direction, and the near horizontal edges are normally used to measure the SFR in the slow scan
direction. The SFR measurement can be performed automatically by image processing software. To perform
the measurement, the scanner output data along the edges of the slanted square in the middle of the test
chart are analysed by a mathematical algorithm.
The SFR algorithm is given in Annex B. A flow chart form and a diagram depicting the key steps of the SFR
algorithm, and sample C-code, is given in ISO 12233. The SFR algorithm can be implemented as part of an
1)
easy-to-use image processing or analysis software package . The algorithm can automatically compute and
report the SFR, using image data from a user-defined rectangular region of the image which represents a
vertically oriented slanted edge, depicting a “horizontal” transition. To measure the SFR in the orthogonal
direction, a horizontally oriented edge is used, and the digital image data is rotated 90° before performing the
calculation. If the image is a colour image, the algorithm performs calculations on the separate red, green and
blue colour image records. The image code values are linearized by inverting the scanner OECF and
converting the print densities to reflectances.
Next, for each line of pixels perpendicular to the edge, the edge is differentiated using the discrete derivative
“− 0,5; + 0,5”, meaning that the derivative value for pixel “X” is equal to − 1/2 times the value of the pixel
immediately to the left, plus 1/2 times the value of the pixel to the right. The centroid of this derivative is
calculated to determine the position of the edge on each line. A best line fit to the centroids is then calculated.
Error messages shall be reported if any centroid is within 2 pi
...

SLOVENSKI STANDARD
SIST ISO 16067-1:2011
01-julij-2011
)RWRJUDILMD0HULWYHSURVWRUVNHORþOMLYRVWLHOHNWURQVNLKVNHQHUMHY]DIRWRJUDIVNH
VOLNHGHO6NHQHUML]DUHIOHNVLMVNHPHGLMH
Photography - Spatial resolution measurements of electronic scanners for photographic
images -- Part 1: Scanners for reflective media
Photographie - Mesurages de résolution spatiale de scanners électroniques pour images
photographiques -- Partie 1: Scanners pour milieux réfléchissants
Ta slovenski standard je istoveten z: ISO 16067-1:2003
ICS:
37.040.10 Fotografska oprema. Photographic equipment.
Projektorji Projectors
SIST ISO 16067-1:2011 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ISO 16067-1:2011

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SIST ISO 16067-1:2011


INTERNATIONAL ISO
STANDARD 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 résolution spatiale de scanners
électroniques pour images photographiques —
Partie 1: Scanners pour milieux réfléchissants




Reference number
ISO 16067-1:2003(E)
©
ISO 2003

---------------------- Page: 3 ----------------------

SIST ISO 16067-1:2011
ISO 16067-1:2003(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem 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, without permission in writing from either ISO at the address below or
ISO's 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 [e-mail]
Web www.iso.org
Published in Switzerland

ii © ISO 2003 — All rights reserved

---------------------- Page: 4 ----------------------

SIST ISO 16067-1:2011
ISO 16067-1:2003(E)
Contents 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 Temperature 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 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 2003 — All rights reserved iii

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SIST ISO 16067-1:2011
ISO 16067-1:2003(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
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 closely with the
International Electrotechnical Commission (IEC) on all matters of 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 to 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 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 reflective media
 Part 2: Film scanners
iv © ISO 2003 — All rights reserved

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SIST ISO 16067-1:2011
ISO 16067-1:2003(E)
Introduction
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 of 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 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 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 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 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 equivalent to a moving knife edge measurement.


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INTERNATIONAL STANDARD ISO 16067-1:2003(E)

Photography — Spatial resolution measurements of electronic
scanners for photographic images —
Part 1:
Scanners for reflective media
1 Scope
This part of ISO 16067 specifies methods for 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
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, Photography — 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 apply.
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 significant energy at
frequencies higher than the Nyquist frequency of the system
NOTE These artefacts usually manifest themselves as moiré patterns in repetitive image features or as jagged
“stairstepping” at edge transitions.
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3.3
digital output level
digital 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 characteristics 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 direction 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 correct 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 algorithm, 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 image 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 sampling 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
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NOTE 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.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 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 input 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
exhibiting 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 characteristics 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 transmittance values in a prescribed spatial arrangement
NOTE Bitonal patterns are typically used to measure resolving power, limiting resolution and SFR.
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3.20.2
grey-scale patterns
pattern that is spectrally neutral or effectively spectrally neutral, and which 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 with 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 correspond 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 shall 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.
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4.2.3 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 aliasing. (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 target's frequency content is
0,2. These declarations should be 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 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 example equation corresponding to Figure 2 is the n-th order polynomial:
1 2 3 4 5 6 7
Target modulation = C + C ν + C ν + C ν + C ν + C ν + C ν + C ν (1)
0 1 2 3 4 5 6 7
where
ν is the spatial frequency in terms of line pairs per millimetre;
C are the polynomial coefficients associated with the ith term
i
C = 1,000 0e + 00 C = − 1,016 1e − 02 C = − 5,938 9e − 03 C = 5,611 6e − 04
0 1 2 3
C = − 2,344 3e − 05 C = 5,099 7e − 07 C = − 5,612 0e − 09 C = 2,468 1e − 11
4 5 6 7

X spatial frequency (in cycles per millimetre)
Y modulation
Figure 2 — Example of the frequency content of a reflection edge's spatial derivative
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4.3 Test chart elements
4.3.1 General
For testing purposes, the test chart (Figure 3) shall include elements for measuring the scanner opto-
electronic conversion function and SFR in the fast-scan and slow-scan directions.

Figure 3 — Test chart elements (see subclauses indicated and Figure 1)
4.3.2 Grey-scale patches
The test chart shall include twenty neutral grey-scale patches with specified visual densities for measuring the
scanner OECF. The maximum patch reflection density shall be at least 1,5 times the maximum density of the
central slanted square (see 4.3.3). The minimum patch density shall be equal to the reflective media minimum
density. The spatial arrangement of the patches shall be designed to minimize flare between adjacent patches
as depicted in Figure 1. A suggested spatial arrangement is given in Annex A.
4.3.3 Near-vertical and near-horizontal slanted edges
The test chart shall include a slanted (approximately 5°) square feature used to measure vertical- and
horizontal-edge SFR. The density of the square shall exceed that of the immediate surrounding area. The
central square's surround density shall have a visual diffuse density of W 0,40 and u 0,60. The square patch
density shall have a visual diffuse density of W 1,00 and u 1,20.
NOTE These values ensure sufficiently low edge transition contrasts to facilitate robust SFR measurements.
4.3.4 Near-45° edges
The test chart should include a diamond-shaped feature (approximately 50° from vertical) for measuring the
SFR at 45°. The density of this feature should match that of the surround area defined in 4.3.3.
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4.3.5 Vertical and horizontal square wave features
The test chart should include horizontal and vertical square wave features of extended length to aid in the
visual detection of aliasing. These features shall have a spatial frequency of 6 cycles/mm, 8 cycles/mm,
12 cycles/mm, 24 cycles/mm and 40 cycles/mm. The minimum and maximum densities should nominally
match the D and D of the grey-scale patches.
max min
NOTE The square wave features have a spatial frequency corresponding to approximately 300 DPI, 400 DPI,
600 DPI, 1 200 DPI and 2 000 DPI.
4.3.6 Near-vertical and near-horizontal square features
The test chart should include horizontal and vertical square wave features of extended length to aid in the
detection of aliasing. These features shall have the same frequencies as indicated in 4.3.8. The minimum and
maximum densities should nominally match the D and D of the grey-scale patches.
max min
NOTE These slanted lines eliminate the ambiguity of phase induced patterns in resolution measurements.
4.3.7 Fiducial marks
The test chart should include fiducial marks in the corners of the central target features. These marks can aid
in the automatic analysis of grey patch and slanted edge features for scanner OECF and SFR measurements.
NOTE The vertical and horizontal distance between fiducial marks in Figure 1 is 50,8 mm. This distance can be used
to verify scanner sampling frequency.
4.3.8 Slightly slanted extended lines
The test chart should include horizontal and vertical, slightly slanted lines for the checking of scan linearity,
“stairstepping” and cyclical scanner behaviours such as colour channel misregistration.
4.3.9 Bitonal spatial resolution elements
The test chart should include bitonal spatial patterns to aid in evaluating limiting visual resolution. These
elements should be of high contrast (D and D ) and accompanied by numbered groups keyed for
max min
recognition of spatial frequencies.
4.3.10 Administrative elements
The test chart should include administrative elements to aid in tracking the genealogy and characteristics of
the test chart being used. These may be items such as manufacturer's insignia, creation date or barcode.
5 Test conditions
5.1 General
The following measurement conditions should be used as nominal conditions when measuring the scanner
OECF and spatial resolution. If it is not possible or appropriate to achieve these nominal operating conditions,
the actual operating conditions shall be listed along with the reported results.
5.2 Temperature and relative humidity
The ambient temperature during the acquisition of the test data shall be (23 ± 2) °C, as specified in ISO 554,
and the relative humidity should be (50 ± 20) %.
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5.3 Luminance and colour measurements
For a colour scanner, the spatial resolution measurements should be performed on each colour record
separately. If desired, a luminance resolution measurement may be made on a luminance signal formed from
an appropriate combination of the colour records. In either case, the channel on which the measurement is
performed shall be reported.
5.4 Linearization
The scanner output signal will likely be a non-linear function of the print density values. Linearization is
accomplished by applying the inverse of the scanner OECF to the output signal via a lookup table or
appropriate equation and then converting from density to reflectance. The measurement of the scanner OECF
shall be as specified in Clause 6.
5.5 Scanner settings
The spatial resolution should be measured with the manufacturer's recommended default settings. If different
settings are used, they shall be reported.
6 Measuring the scanner OECF
The scanner OECF shall be calculated from values determined from the same chart and scan as the values
for the resolution measurements. Many scanners will automatically adapt to the dynamic range and the
luminance distribution of the print. The results may also differ if the scan mode is grey scale or RGB.
A minimum of four trials shall be conducted for each resolution measurement and scanner OECF
determination. A trial shall consist of one scan of the test chart. For each trial, the digital output level shall be
determined from a 64 pixel by 64 pixel area located at the same relative position in each patch. It is possible
that with very low resolution scans the images of the test chart patches will not be large enough to contain a
64 pixel by 64 pixel area. In this case, the sample area should be slightly smaller than the image of the patch
area so that the effects of imaging the patch edge are not included.
Identical, non-aligned patches may be averaged, or the patch with the least scanning artefacts, such as dust
or scan lines, may be used. The scanner OECF so determined shall be used to calculate the resolution
measurements for this trial. If the scanner OECF is reported, the final digital output level data presented for
each step density shall be the mean of the digital output levels for all the trials.
7 Limiting visual resolution and its relation to SFR
To determine the limiting visual resolution, the image of the test target is reproduced on a monitor or
hard-copy print, and the visual resolution is subjectively judged. To ensure that the monitor or hard-copy
printer does not reduce the visual resolution value, the digital image may be enlarged by pixel replication prior
to viewing or printing, so that the individual pixels are visible. Observers should be well acquainted with the
appearance of aliasing, so that they do not seriously misjudge the visual resolution of the scanner. The test
chart includes vertical and horizontal elements that are used to perform this test. The limiting visual resolution
is the lowest value of the test pattern where the individual black and white lines can no longer be
distinguished, or are reproduced at a spatial frequency lower than the spatial frequency of the corresponding
area of the test chart, as a result of aliasing. The limiting visual resolution value shall not exceed the
half-sampling frequency. Should this frequency exceed the half-sampling frequency, the limiting visual
resolution shall be the spatial frequency associated with the half-sampling frequency. The limiting visual
resolution in the fast scan direction is normally determined by observing the vertical elements. The visual
resolution in the slow scan direction is normally determined by observing the horizontal elements.
A very good correlation between limiting visual resolution and the spatial frequency associated with a
0,10 SFR response has been found experimentally. Should this frequency exceed the half-sampling
frequency, the limiting visual resolution shall be the spatial frequency associated with the half-sampling
frequency.
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8 Edge SFR test measurement
The spatial frequency response (SFR) of a print scanner is measured by analysing the scanner data near a
slanted edge transition. The near vertical edges shown in Figure 1 are normally used to measure the SFR in
the fast scan direction, and the near horizontal edges are normally used to measure the SFR in the slow scan
direction. The SFR measurement can be performed automatically by image processing software. To perform
the measurement, the scanner output data along the edges of the slanted square in the middle of the test
chart are analysed by a mathematical algorithm.
The SFR algorithm is given in Annex B. A flow chart form and a diagram depicting the key steps of the SFR
algorithm,
...