ISO 10505:2009

INTERNATIONAL ISO
STANDARD 10505
First edition
2009-05-15
Photography — Root mean square
granularity of photographic films —
Method of measurement
Photographie — Moyenne quadratique granulaire de films
photographiques — Méthode de mesure

Reference number
©
ISO 2009
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ii © ISO 2009 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Measurement instrument . 3
4.1 General. 3
4.2 Microdensitometer. 3
4.3 Spectral products . 6
4.4 Spatial frequency response. 7
4.5 Scanning motion. 7
5 Instrument electronics . 8
5.1 Conversion to density . 8
5.2 Temporal frequency response of the instrument. 8
5.3 Instrument noise . 8
6 Diffuse rms-granularity . 8
6.1 Optical geometry. 8
6.2 Diffuse conversion factor g. 9
7 Preparation of specimens. 9
7.1 Sampling and storage . 9
7.2 Exposure. 10
7.3 Processing. 10
7.4 Specimen uniformity . 10
7.5 Sampled area. 10
8 Operation of the measurement instrument. 10
8.1 Positioning the specimen . 10
8.2 Specimen scanning . 10
8.3 Control of focus . 10
8.4 Rate of scan. 11
8.5 Density mode . 11
9 Method of test . 11
9.1 Principle. 11
9.2 Statistical background . 11
9.3 Construction of the median estimator and the 95 % confidence intervals. 12
9.4 Instrument noise . 13
9.5 Diffuse rms-granularity . 14
9.6 Uncertainty of the rms-granularity result. 14
9.7 Reporting results . 14
9.8 Summary of rms-granularity characterization parameters . 15
Annex A (informative) Typical viewing magnifications for critical naked-eye viewing . 16
Annex B (informative) Limiting the temporal frequency response of the measuring instrument . 18
Annex C (informative) The effects of specimen non-uniformity. 20
Annex D (informative) Derived constants c for subgroup sizes 10, 20, …, 200 . 21
Annex E (informative) Determination of sample size for specified precision and subgroup size. 22
Bibliography . 24

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
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established has the right to be represented on that committee. International organizations, governmental and
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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 10505 was prepared by Technical Committee ISO/TC 42, Photography.
iv © ISO 2009 – All rights reserved

Introduction
This International Standard specifies procedures for measuring and computing the root mean square
granularity (rms-granularity) of photographic films. Its purpose is to provide guidance in making accurate
measurements, and also to provide an objective basis for comparing films. This International Standard
describes a method for making accurate rms-granularity measurements in the presence of instrument noise
and minor sample imperfections.
In principle, the measurement of rms-granularity is straightforward, but its determination with accuracy is not a
trivial matter. Experience has shown that the preparation of an imperfection-free sample is virtually impossible
in usual practice. Therefore, considerable attention has been devoted to the definition of a method of
accurately estimating the rms-granularity of a film in the presence of density fluctuations not caused by the
intrinsic grain structure of the film.
Research in rms-granularity (see Reference [10]) has pointed out that the inclusion of several “artefact-
induced” data values in a set of several thousand “grain-produced” data values may result in large errors in
the rms-granularity estimate. Under these circumstances, the traditional method for estimating rms-granularity
produces higher rms-granularity estimates than the new method. It can also be shown that this method
produces results that are identical to those produced by the traditional method when using artefact-free data.
In either case, it is important to bear in mind that rms-granularity is a statistical estimate which is necessarily
reported with its associated confidence intervals. In addition, the measurement process recognizes and
accounts for the presence of instrument noise that can affect the accuracy of the rms-granularity estimate.

INTERNATIONAL STANDARD ISO 10505:2009(E)

Photography — Root mean square granularity of photographic
films — Method of measurement
1 Scope
This International Standard describes a method for determining the intrinsic root mean square granularity
(rms-granularity) of photographic films. Intrinsic rms-granularity refers to those density fluctuations produced
solely by the distribution of developed image forming centres in the photographic emulsion.
Continuous-tone monochrome (silver absorbing species) and colour (dye absorbing species) materials coated
on a transmitting support can be measured by the procedures described in this International Standard. This
International Standard is intended for imaging systems with viewing magnifications between 5× and 12× (see
Annex A).
The following kinds of granularity measurements are not covered by this International Standard, even though
they are photographically important:
⎯ reflecting materials (photographic papers);
⎯ materials having emulsion coated on both sides of the support (e.g. some X-ray films);
⎯ the estimation of the noise power spectrum (Wiener spectrum).
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 5-2, Photography — Density measurements — Part 2: Geometric conditions for transmission density
ISO 5-3, Photography — Density measurements — Part 3: Spectral conditions
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
transmittance factor
T
ratio of the measured flux transmitted by a specimen to the measured flux when the specimen is removed
from the sampling aperture of the measuring device
φ
T
NOTE T =
φ
J
where
φ is the transmitted flux;
T
φ is the aperture flux.
J
3.2
transmission density
D
T
logarithm to the base 10 of the reciprocal of the transmittance factor, T
NOTE D = log 1/ T .
T 10
3.3
microtransmittance factor
transmittance factor of a small area of a film or plate, measured using a suitable instrument such as a
microphotometer
NOTE In general, the microtransmittance factor of a uniformly exposed and developed film sample varies from
point-to-point on the surface. The measured microtransmittance factor of a given film or plate can depend on the optical
geometry of the instrument in which it is measured.
3.4
microdensity
D
transform of the microtransmittance factor in accordance with the usual relation D = log 1/T
3.5
graininess
sensation produced, in the mind of an observer viewing a photographic image, by random inhomogeneity in
what should be structu
...