ISO 12231:1997
(Main)Photography — Electronic still-picture cameras — Terminology
Photography — Electronic still-picture cameras — Terminology
Photographie — Caméras de prises de vue électroniques — Terminologie
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Standards Content (Sample)
INTERNATIONAL
IS0
STANDARD
12231
First edition
1997-06-I 5
Photography - Electronic still-picture
cameras - Terminology
Photographic - Cameras de p&es de we 6lectroniques - Terminologie
Reference number
IS0 12231:1997(E)
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IS0 12231 :1997(E)
IS0 (the international Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for which
a technical commitee 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. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
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.
International Standard IS0 12231 was prepared by Technical Committee
I SO/TC 42, Photography.
0 IS0 1997
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 the publisher.
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ii
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@ IS0 IS0 12231:1997(E)
Introduction
Electronic photography concepts are drawn from traditional photography,
electronics, video, and information technology. In some cases the concepts
must be redefined to apply to electronic photography. For example, unlike
traditional photography, measurements cannot be defined in terms of “film”
or “sensitized material ”, since images acquired by electronic still cameras
are stored electronically and not immediately exposed on film. The
meaning of shutters and exposure time is also different for electronic still
cameras, because an electronic imaging sensor, usually a charged-
coupled device (CCD), has image acquisition characteristics which are
different from film.
The purpose of this terminology is to standardize the use and meaning of
terms associated with electronic still-picture cameras. It is organized
alphabetically and follows natural (English) word order whenever possible.
The majority of the terms listed in this International Standard are derived
from the first three references listed in the annex.
. . .
III
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INTERNATIONAL STANDARD @ IS0
IS0 12231:1997(E)
“average” modulation of an electronic still-picture
Photography -
camera when imaging a frequency burst of
Electronic still-picture cameras -
constant spatial frequency.
Terminology
24
1 Scope
aspect ratio cf. image aspect ratio, pixel aspect
ratio.
This International Standard defines terms used in
electronic photography.
25
cbmpression cf. image compression.
Only terms related to electronic still-picture
cameras are included. These terms are relevant to
26
the current tasks or of general interest in electronic
ebge spread function (ESF)
photography.
< Resolution > The normalized spatial signal
distribution in the output of an imaging system
resulting from imaging a theoretical infinitely sharp
edge. cf. line spread function, point spread
2 Definitions
function.
The source of most of the terms in this International
27
Standard are the documents on electronic still-
eifectively spectrally neutral
picture cameras developed by ISO/TC 42/M/G 18
< Resolution > Having relative spectral radiance
and listed as the first three references in the annex.
characteristics which result in a specific imaging
Definitions from some existing International
system producing the same output as for a
Standards, e.g. optical transfer function, are
spectrally neutral object. cf. spectra//y neutral.
included here for completeness.
The term given in angle brackets prior to the 28
definition references one of the first three eiectronic still-picture camera
documents listed in the annex that serves as the < IS0 speed > A camera incorporating an image
source of the definition. At the end of some sensor which outputs an analog or digital signal
definitions, a phrase in italic fount, beginning with representing a still picture, or records an analog or
cf., lists other terms that are related to the term
digital signal representing a still picture on a
being defined. removable media, such as a memory card or
magnetic disk.
21
29
abdressable photoelements
electronic shutter
< Resolution > The number of active
< IS0 speed > Any one of three devices for
photoelements on an image sensor. This is equal
controlling the exposure time of an electronic still-
to the number of active lines of photoelements
picture camera.
times the number of active photoelements per line.
2.9.1
electronically shuttered sensor
NOTE: This term is included to provide an
A component of an electronic still camera
appropriate term for describing the dimensionality
which electronically controls the image sensor
of image sensors. The term resolution should
itself in order to set the exposure time.
not be used when referring to the number of
2.9.2
addressable photoelements on an image sensor.
electromechanical shutter
A mechanical shutter which is electronically
22
controlled.
aiiasing
2.9.3
< Resolution > Output image artifacts that occur in
electro-optical shutter
a sampled imaging system for input images having
An electronically driven device in front of the
significant energy at frequencies higher than the
sensor which changes the optical path
Nyquist frequency of the system. Aliasing can be
transmittance.
prevented by filtering the input image to suppress
these high spatial frequencies prior to sampling,
2.10
but such filtering may not be desirable.
exposure index
23 < IS0 speed > A numerical value which is
inversely proportional to the exposure provided to
aiiasing ratio
an image sensor to obtain an image. Images
< Resolution > The value equal to the “maximum
obtained from a camera using a range of exposure
minus minimum” modulation divided by the
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IS0 12231:1997(E) @ IS0
2.13.3
index values will normally provide a range of
image quality levels. cf. /SO speed of an electronic movie frame or studio frame
still-picture camera. When inter/aced video is applied to still-picture
imaging, the resulting movie frame consists of
2.11 two fields taken simultaneously.
exposure process
< IS0 speed > Various methods to capture images 2.14
in the electronic still-picture camera. file system
2.11 .l < Memory > The software structure which
specifies how the data is logica ly organized on a
single exposure
given storage media.
Acquiring a picture by a single exposure, with
one or more image sensors, that exposes all
sensor pixels, all colours, and all image 2.15
locations at the same time. gamma correction
2.11.2 < Resolution > A process whicl
I alters the image
colour sequential data in order to modify the tone reproduction.
Acquiring a picture by combining repeated
exposures to capture different colour NOTE: The gamma correction is usually an
components; for example, by means of three algorithm, lookup table, or circuit which operates
colour illuminations, or by three colour filters. separately on each colour component of an image.
2.11.3
2.16
time sequential
Acquiring a picture by combining repeated horizontal resolution
exposures to capture different spatial < Resolution > A resolution value measured in the
components; for example, with a line array (line line readout (fast readout) direction, typically using
a vertically oriented resolution wedge.
scanning) or an area array. With a line sensor,
the picture is acquired by optical or physical
sub-scanning with an image sensor in one 2.17
dimension. With an area array, for example, image aspect ratio
repeated exposures may integrate smaller < Resolution > The ratio of the image width to the
pictures into a larger picture by means of image
image height. cf. pixel aspect ratio.
sensor shifting.
2.18
2.12
image compression
exposure series
< Resolution > A process that alters the way
< IS0 speed > A series of images of the same image data is encoded in order to reduce the
subject taken using different exposure settings. average size of an image file.
2.13 2.19
f ieldkframe image data format
< Memory > The structure and content which
Types of picture formats formed by video signals.
2.13.1 specifies image data and the organization of the
image-related data in a device-independent
field
manner.
For an inter/aced video signal, a “field” is the
assembly of alternate (odd or even) lines of a
2.20
frame. Therefore an inter/aced frame is
composed of two fields, an odd field and an image sensor
< IS0 speed > An electronic device which
even field, representing the odd- and even-
converts incident electromagnetic radiation into an
numbered lines respectively.
electronic signal; for example, a charge coupled
NOTE: Adapted from ISO/IEC 13818-2:1996.
device (CCD) array.
2.13.2
frame
2.21
A frame contains lines of spatial information of
imager size (for an area array sensor)
a video signal. For progressive video, these
< Resolution > The physical dimensions, height
lines contain samples starting from one time
and width, of the photoresponsive area of an
instant and continuing through successive lines
imaging sensor.
to the bottom of the frame. For inter/aced video
a frame consists of two fields, an odd field and
NOTE: The following addition is adapted from
an even field. One of these fields will
EIAJ EDX-5301: The measure of imager size for a
commence one field period later than the other.
video-based still-picture camera is described by
the approximate diameter of a tube-type image
NOTE: Adapted from ISO/IEC 13818.2:1996.
2
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@ IS0 IS0 12231:1997(E)
distinguishes only test patterns having a lower
sensor which is equivalent to a diagonal length of
LW/PH.
the solid state image sensor. The expressions of
diameters of 2/3, l/2, l/3 or l/4 inch (type)
2.27
correspond to actual imager sizes of 6,6 mm x
8,8 mm, 4,8 mm x 6,4 mm, 3,6 mm x 4,8 mm, and media profile
2,7 mm x 3,6 mm respectively, for 4:3 image < Memory > The portion of the memory module
aspect ratio sensors.
specification which is specific to a given memory
technology; including the form factor,
2.22
interconnection and access protocol. cf. image
image storage application profile (ISAP) storage application profile, image data format.
< Memory > The media profile plus the image data
format. cf. media profile, image data format. 2.28
memory module
2.23 < Memory > The physical implementation of
IS0 speed of an electronic still-picture camera Removable Memory, containing the image data
< IS0 speed > A numerical value calculated from format combined with a specified physical form
the exposure provided at the focal plane of an factor, interconnect definition and access protocol.
electronic camera to produce specified camera
2.29
output signal characteristics using the methods
described in the referenced standard. An IS0
modulation
speed value of 100 is designated as IS0 100. cf. < Resolution > The difference between the
exposure index.
minimum and maximum signal levels divided by
the sum of these levels.
2.24
limiting resolution 2.30
< Resolution > The value of that portion of a
modulation transfer function (MTF)
specified resolution test pattern, measured in line
< Resolution > The modulus of the optical transfer
height (LW/PH), which
widths per picture function OTF(r,s). [ISO 93341 cf. optical transfer
corresponds to an average modulation value equal function, spatial frequency response.
to some specified percentage of the modulation
value at a specified reference, also measured in
2.31
LW/PH. For example, the l
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