ISO 16067-1:2003

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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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
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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 consta
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