ISO 16067-1:2003

SLOVENSKI STANDARD
01-julij-2011
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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
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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 2003
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©  ISO 2003
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ii © ISO 2003 — All rights reserved

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

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

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.

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.
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
2 © ISO 2003 — All rights reserved

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.
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.
4 © ISO 2003 — All rights reserved

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
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.
6 © ISO 2003 — All rights reserved

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 ac
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