ISO 12231:2005

Photography - Electronic still picture imaging - Vocabulary

ISO 12231:2005 defines terms used in electronic still picture imaging. Only terms related to electronic still picture imaging are included. These terms are relevant to the current tasks or are of general interest in electronic still picture imaging.

Photographie — Prises de vue électroniques — Vocabulaire

Fotografija - Elektronsko upodabljanje mirujočih slik - Pojmovnik

Ta mednarodni standard opredeljuje pojme, ki se uporabljajo pri elektronskem upodabljanju mirujočih slik. Vključeni so le izrazi, povezani z elektronskim upodabljanjem mirujočih slik. Ti izrazi se nanašajo na trenutne naloge ali so v splošnem interesu pri elektronskem upodabljanju mirujočih slik.

General Information

• Status: Withdrawn
• Publication Date: 02-Feb-2005
• Withdrawal Date: 02-Feb-2005
• ICS: 01.040.37 - Image technology (Vocabularies)
• ICS: 37.040.10 - Photographic equipment. Projectors
• Technical Committee: ISO/TC 42 - Photography
• Drafting Committee: ISO/TC 42/WG 18 - Electronic still picture imaging
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 23-Jan-2012
• Completion Date: 13-Dec-2025
• Ref Project: SIST ISO 12231:2011 - Photography - Electronic still picture imaging - Vocabulary

Relations

• Consolidated By: ISO 7539-6:2011 - Corrosion of metals and alloys - Stress corrosion testing - Part 6: Preparation and use of precracked specimens for tests under constant load or constant displacement
• Effective Date: 06-Jun-2022
• Revised: ISO 12231:2012 - Photography - Electronic still picture imaging - Vocabulary
• Effective Date: 28-Feb-2009
• Revises: ISO 12231:1997 - Photography - Electronic still-picture cameras - Terminology
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 12231
Second edition
2005-02-01
Photography — Electronic still picture
imaging — Vocabulary
Photographie — Prises de vue électroniques — Vocabulaire

Reference number
©
ISO 2005
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©  ISO 2005
The reproduction of the terms and definitions contained in this International Standard is permitted in teaching manuals, instruction
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ii © ISO 2005 – All rights reserved

Contents Page
Foreword.iv
Introduction .v
1 Scope.1
2 Terms and definitions.1
Annex A (informative) Other terms and definitions .21
Bibliography .42
Alphabetical index .43

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 12231 was prepared by Technical Committee ISO/TC 42, Photography.
This second edition cancels and replaces the first edition (ISO 12231:1997), which has been technically
revised.
iv © ISO 2005 – All rights reserved

Introduction
Electronic still picture imaging concepts are drawn from traditional photography, electronics, video, and
information technology. In some cases the concepts must be redefined to apply to electronic still picture
imaging. For example, unlike traditional photography, measurements cannot be defined in terms of “film” or
“sensitized material”, since images acquired by digital image capture devices are stored electronically and are
not immediately exposed on film. The meaning of shutter and exposure time is also different for digital image
capture devices, because an electronic imaging sensor typically has image acquisition characteristics that are
different from those of film.
The purpose of this vocabulary is to standardize the use and meaning of terms associated with electronic still
picture imaging. It is organized alphabetically and follows natural (English) word order wherever possible. The
source of most of the terms in this International Standard are the documents on electronic still picture imaging
developed by ISO/TC 42/WG 18, and ISO/TC 42/JWG 20 and 23 (with ISO/TC 130). Definitions from some
other TC 42 International Standards, e.g. flare, are also included for completeness. The ISO numbers
provided in brackets following the definition reference documents listed in the bibliography that serve as the
source of the definition. At the end of some definitions, other terms are listed (preceded by “cf.”) that are
related to the term being defined. An alphabetical index is included at the end of the document.
Terms from working drafts and committee drafts of standards under development within ISO/TC 42 (as of
15 August 2002) are provided in Annex A. These terms are more likely to change as the source documents
progress. Definitions are provided in this International Standard to facilitate communication. Where possible,
the latest draft of the source document should be reviewed to see if a more current definition is available.
Future revisions of this International Standard will include updated terms and definitions consistent with the
source documents at the time the revision is prepared.

INTERNATIONAL STANDARD ISO 12231:2005(E)

Photography — Electronic still picture imaging — Vocabulary
1 Scope
This International Standard defines terms used in electronic still picture imaging.
Only terms related to electronic still picture imaging are included. These terms are relevant to the current
tasks or are of general interest in electronic still picture imaging.
2 Terms and definitions
2.1
addressable photoelements
number of active photoelements on an image sensor, which is equal to the number of active lines of
photoelements times the number of active photoelements per line
[ISO 12233, ISO 16067-1, ISO 16067-2, ISO 21550]
NOTE The term resolution should not be used when referring to the addressable photoelements. It is possible that the
addressable photoelements may be different for the different colour records of an image. When the signal values of the
photoelements are digitized, the digitized code values may be referred to as picture elements, or pixels.
2.2
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
[ISO 12233, ISO 16067-1, ISO 16067-2, ISO 21550]
NOTE These artefacts usually manifest themselves as moiré patterns in repetitive image features or as jagged stair-
stepping at edge transitions.
2.3
aliasing ratio
value equal to the “maximum minus minimum” modulation divided by the “average” modulation of an
electronic still picture camera when imaging a frequency burst of constant spatial frequency
[ISO 12233]
2.4
analog-to-digital converter
A/D or ADC
circuit that converts an analog signal, having a continuously varying amplitude, to a digitally quantized
representation using binary output signals
2.5
application
image application software for use on a personal computer
[ISO 12234-3]
2.6 Aspect ratio
2.6.1
image aspect ratio
ratio of the image width to the image height
[ISO 12233, ISO 15740]
2.6.2
pixel aspect ratio
ratio of the distance between sampling points in the two orthogonal sampling directions
NOTE 1 If the distances are equal, the pixel aspect ratio equals 1:1, and is said to be “square”.
NOTE 2 Retained from ISO 12231:1997.
2.7
charge coupled device
CCD
type of silicon integrated circuit used to convert light into an electronic signal
2.8
colour filter array
CFA
mosaic or stripe layer of coloured transmissive filters fabricated on top of an imager in order to obtain a colour
image from a single image sensor
2.9
colour matching functions
tristimulus values of monochromatic stimuli of equal radiant power
[CIE Publication 17.4 (845-03-23), ISO 17321-1, ISO 17321-2, ISO 22028-1]
cf. tristimulus value
2.10
colour space
geometric representation of colours in space, usually of three dimensions
[CIE Publication 17.4 (845-03-25), ISO 17321-1, ISO 17321-2, ISO 22028-1]
2.11 Compression
2.11.1
image compression
process that alters the way digital image data are encoded in order to reduce the size of an image file
[ISO 12233]
2.11.2
sound compression
process of altering the sound data coding in order to reduce the size of a sound file in the electronic still
picture camera
[ISO 12234-1]
cf. sound recording
2 © ISO 2005 – All rights reserved

2.12
cycles per millimetre
cy/mm
unit used for specifying resolution characteristics in terms of the response of an imaging system to a linear
radiance sine wave input, as a function of the frequency of the sine wave
[ISO 12233]
NOTE 1 A range of input sine wave frequencies is obtained in ISO 12233 through the use of a sharp edge target.
NOTE 2 Most pictorial imaging systems exhibit non-linear behaviour, which may result in the nature of the target
affecting the measured resolution characteristics. Distance units other than millimetres may also be used.
2.13
DCF
design rule for camera file system
design rules for camera file system as specified in ISO 12234-3
NOTE DCF provides a standard convention for camera file systems that specifies the file format, folders, and naming
conventions in order to promote file interoperability between conforming digital still photography devices.
2.14
DCF basic file
image file stored directly under a DCF directory, having a DCF filename and the extension “JPG” and having
the DCF-defined data structure, based on the Exif standard
[ISO 12234-3]
2.15
DCF basic main image
Exif primary image included in a DCF basic file
[ISO 12234-3]
2.16
DCF basic thumbnail
Exif thumbnail image included in a DCF basic file
[ISO 12234-3]
2.17
DCF-compatible
meeting the requirements of ISO 12234-3
[ISO 12234-3]
2.18
DCF directory
directory under the DCF image root directory for storing images, created in accordance with the DCF directory
rules
[ISO 12234-3]
2.19
DCF directory name
directory name assigned in accordance with the DCF directory-naming conventions
[ISO 12234-3]
2.20
DCF extended image file
image file stored directly under a DCF directory, having an extension and data structure different from a DCF
basic file
[ISO 12234-3]
2.21
DCF file name
file name assigned in accordance with the DCF file-naming conventions
[ISO 12234-3]
2.22
DCF image root directory
directory directly under the root directory, created in accordance with the DCF directory rules
[ISO 12234-3]
2.23
DCF media
removable memory recorded in accordance with the DCF requirements
[ISO 12234-3]
2.24
DCF object
group of files having the same file number stored in the same DCF directory
[ISO 12234-3]
2.25
DCF thumbnail file
compressed file for storing the thumbnail image of a DCF extended image file
[ISO 12234-3]
2.26
depth of field
difference between the maximum and minimum distances from a camera lens's front nodal point to objects in
a scene that can be captured in acceptably sharp focus
2.27
digital output level
digital code value
numerical value assigned to a particular output level
[ISO 14524, ISO 15739, ISO 16067-1, ISO 16067-2, ISO 21550]
2.28
digital still camera
DSC
device which incorporates an image sensor and produces a digital signal representing a still picture
[ISO 12234-3, ISO 17321-1, ISO 17321-2]
NOTE A digital still camera is typically a portable, hand-held device. The digital signal is usually recorded on a
removable memory, such as a solid-state memory card or magnetic disk.
4 © ISO 2005 – All rights reserved

2.29
directory number
three-digit number which is comprised of the first three characters of the DCF directory name
[ISO 12234-3]
2.30
edge spread function
ESF
normalized spatial signal distribution in the linearized output of an imaging system resulting from imaging a
theoretical infinitely sharp edge
[ISO 12233, ISO 16067-1, ISO 16067-2, ISO 21550]
cf. line spread function, point spread function
2.31
effectively spectrally neutral
having spectral characteristics which result in a specific imaging system producing the same output as for a
spectrally neutral object
[ISO 12233, ISO 16067-1, ISO 16067-2, ISO 21550]
cf. spectrally neutral
2.32
electronic scanner(1)
〈photographic films〉 scanner incorporating an image sensor that outputs a digital signal representing a still film
image
[ISO 16067-2, ISO 21550]
2.33
electronic scanner(2)
〈photographic prints〉 scanner incorporating an image sensor that outputs a digital signal representing a still
print image
[ISO 16067-1]
2.34
electronic shutter
any one of three devices for controlling the exposure time of an electronic still picture camera
2.34.1
electronically shuttered sensor
component of an electronic still camera which electronically controls the image sensor itself in order to set the
exposure time
2.34.2
electromechanical shutter
mechanical shutter which is electronically controlled
2.34.3
electro-optical shutter
electronically driven device in front of the image sensor which changes the optical path transmittance
2.35
electronic still picture camera
camera incorporating an image sensor that outputs an analog or digital signal representing a still picture,
and/or records an analog or digital signal representing a still picture on a removable medium, such as a
memory card or magnetic disc
[ISO 12232, ISO 12233, ISO 15739]
2.36
Exif
exchangeable image file format
digital still camera image file format standard of the Japan Electronic Industry Development Association
(JEIDA)
[ISO 12234-3]
NOTE The JPEG version of Exif provides a compressed file format for digital cameras in which the images are
compressed using the baseline JPEG standard described in ISO/IEC 10918-1, and metadata and thumbnail images are
stored using TIFF tags within an application segment at the beginning of the file.
2.37
exposure index
numerical value that is inversely proportional to the exposure provided to an image sensor to obtain an image
[ISO 12232]
NOTE Images obtained from a camera using a range of exposure index values will normally provide a range of image
quality levels.
2.38
exposure process
various methods to capture images in the electronic still picture camera
2.38.1
single exposure
acquisition of a picture by a single exposure, with one or more image sensors, that exposes all sensor pixels,
all colours, and all image locations at the same time
2.38.2
colour sequential exposure
acquisition of a picture by combining repeated exposures to capture different colour components
NOTE Colour sequential exposure can be by means of three colour illuminations, or by three colour filters.
2.38.3
time sequential exposure
acquisition of a picture by combining repeated exposures to capture different spatial components
NOTE Time sequential exposure can be with a line array (line scanning) or an area array. With a line array, the picture is
acquired by optical or physical sub-scanning with an image sensor in one dimension. With an area array, repeated
exposures may integrate smaller pictures into a larger picture by means of image sensor shifting.
2.39
exposure series
series of images of the same subject taken using different exposure index values
[ISO 12232]
6 © ISO 2005 – All rights reserved

2.40
fast scan direction
scan direction corresponding to the direction of the alignment of the addressable photoelements in a linear
array image sensor
[ISO 16067-1, ISO 16067-2, ISO 21550]
2.41
file extension
three identifying characters used in the DOS/FAT file system following the file name and dot
[ISO 12234-3]
2.42
file name
eight-character file name of the DOS/FAT file system, excluding the dot and file extension
[ISO 12234-3]
2.43
file number
four-digit number which comprises the last four characters of the DCF file name
[ISO 12234-3]
2.44
file system
software structure which specifies how the data are logically organized on a given storage medium
[ISO 12234-1, ISO 12234-2]
2.45
flare
light falling on an image, in an imaging system, which does not emanate from the subject point
[ISO 3664]
cf. veiling glare
NOTE Veiling glare is also sometimes referred to as flare.
2.45.1
veiling flare
relatively uniform but unwanted irradiation in the image plane of an optical system, caused by the scattering
and reflection of a proportion of the radiation which enters the system through its normal entrance aperture
[ISO 3664]
NOTE 1 The veiling flare radiation may be from inside or outside the field of view of the system.
NOTE 2 Light leaks in an optical system housing can cause additional unwanted irradiation of the image plane. This
irradiation may resemble veiling flare.
2.46
free characters
five characters following the directory number in a DCF directory name, or the four characters at the beginning
of a DCF file name
[ISO 12234-3]
2.47
gamma correction
signal processing operation that changes the relative signal levels in order to adjust the image tone
reproduction
[ISO 12232, ISO 16067-1, ISO 16067-2, ISO 21550]
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, lookup table, or circuit which operates separately on each
colour component of an image.
2.48
hardcopy
representation of an image on a substrate which is self-sustaining and reasonably permanent
[ISO 3664, ISO 17321-2, ISO 22028-1]
2.49
horizontal pixels
number of luminance pixels of image data in the main (x-axis) scanning direction
[ISO 12234-3]
2.50
horizontal resolution
resolution value measured in the longer image dimension, corresponding to the horizontal direction for a
“landscape” image orientation, typically using a vertically oriented test chart feature
[ISO 12233]
2.51
illuminance scale exposure series
series of exposures produced using a constant exposure time and a varying focal plane illuminance
[ISO 14524]
cf. time scale exposure series
2.52
image data format
structure and content which specifies how the data is logically organized on a given storage medium
[ISO 12234-1, ISO 12234-2]
2.53
image sensor
electronic device that converts incident electromagnetic radiation into an electronic signal
[ISO 12232, ISO 12233, ISO 15739, ISO 16067-1, ISO 16067-2, ISO 21550]
EXAMPLE A charge coupled device (CCD) array.
8 © ISO 2005 – All rights reserved

2.54
image storage application profile
ISAP
media profile plus the image data format
[ISO 12234-1]
NOTE The ISAP specifies all the information necessary to completely implement the removable memory.
2.55
imager size
〈area array sensor〉 physical dimensions, in height and width, of the photoresponsive area of an imaging
sensor
NOTE The following addition is adapted from EIAJ EDX-5301: The measure of imager size for a video-based still picture
camera is described by the approximate diameter of a tube-type image sensor which is equivalent to a diagonal length of
the solid-state image sensor. The expressions of diameters of 2/3, 1/2, 1/3 or 1/4 inch (type) correspond to actual imager
sizes of 6,6 mm × 8,8 mm, 4,8 mm × 6,4 mm, 3,6 mm × 4,8 mm, and 2,7 mm × 3,6 mm respectively, for 4:3 image aspect
ratio sensors.
2.56
incremental gain function
change in the output level (digital code value) divided by the change in the input level (luminance or exposure)
as a function of input level
[ISO 14524, ISO 15739, ISO 21550]
NOTE 1 For the determination of incremental gain values, log input values are not used.
NOTE 2 If the input exposure points are very finely spaced and the output noise is small compared to the quantization
interval, the incremental gain function may have a jagged shape. Such behaviour is an artefact of the quantization process
and should be removed by using an appropriate smoothing algorithm or by fitting a smooth curve to the data. In some
cases it may be desirable to fit a curve to the input-output data and then determine the incremental gain function by taking
the first derivative of the function used for the curve fit.
2.57
incremental output signal
input level (luminance or exposure, not logged) multiplied by the system incremental gain at that level
[ISO 14524, ISO 15739, ISO 21550]
cf. incremental gain function
2.58
incremental signal-to-noise ratio
ratio of the incremental output signal to the root mean square (rms) noise level, at a particular signal level
[ISO 15739, ISO 21550]
NOTE The incremental signal-to-noise ratio is typically expressed as a graph or table showing the rms noise level
versus output signal level for the full range of output signal levels.
2.59
ISO DSC dynamic range
ratio of the maximum luminance level that appears unclipped to the minimum luminance level that can be
reproduced with an incremental signal-to-temporal-noise ratio of at least 1, as determined according to
ISO 15739
[ISO 15739]
2.60
ISO speed
numerical value calculated from the exposure provided at the focal plane of an electronic camera to produce
specified camera output signal characteristics using the methods described in ISO 12232
NOTE The ISO speed should correlate with the highest exposure index value that provides peak image quality for
normal scenes.
2.61
ISO speed latitude
set of two numerical values calculated from the exposure provided at the focal plane of an electronic camera
to produce specified camera output signal characteristics using the methods described in ISO 12232
NOTE The ISO speed latitude should correlate with the range of exposure index values that provide acceptable image
quality for normal scenes.
2.62
JPEG
Joint Photographic Experts Group
image compression method defined in ISO/IEC 10918-1 | ITU-T Recommendation T81
[ISO 12234-3]
2.63
Level 1
playback compatibility level capable of detecting the existence of a DCF basic file and recognizing thumbnail
images
2.64
Level 2
playback compatibility level capable of playing and using DCF basic file main images
2.65
limiting resolution
value of that portion of a specified resolution test pattern, measured in line widths per picture height, that
corresponds to an average modulation value equal to some specified percentage of the modulation value at a
specified reference frequency
[ISO 12233]
EXAMPLE The limiting resolution may be the test pattern value, in line widths per picture height (LW/PH),
corresponding to a camera output modulation level of 5 % of the camera output modulation level at a reference frequency
of 10 LW/PH.
2.66
line pairs per millimetre
lp/mm
metric for specifying resolution in terms of the number of equal width black and white line pairs per millimetre
that can be resolved according to some criterion, such as visual resolution or limiting resolution
[ISO 12233]
NOTE Distance units other than millimetres may also be used.
10 © ISO 2005 – All rights reserved

2.67
line spread function
LSF
normalized spatial signal distribution in the linearized output of an imaging system resulting from imaging a
theoretical infinitely thin line
[ISO 12233]
NOTE If the imaging system is operating in an isoplanatic region and in its linear range, the LSF is equal to the first
derivative of the ESF.
2.68
line widths per picture height
LW/PH
metric for specifying the width of a feature on a test chart, relative to the height of the active area of the chart,
which is equal to the height of the active area of the test chart divided by the width of a black line that is equal
to the total number of lines of the same width which can be placed edge to edge within the height of a test
target or within the vertical field of view of a camera
NOTE Adapted from ISO 12233.
EXAMPLE If the height of the active area of the chart equals 20 cm, a black line of 1 000 LW/PH has a width equal to
20/1 000 cm.
2.69
linearized
digital signal conversion performed to invert either the focal plane or the camera opto-electronic conversion
function (OECF) so that the resulting signal is approximately linearly proportional to focal plane exposure or
scene luminance, respectively
[ISO 12233]
2.70
lines per millimetre
lines/mm
metric for specifying resolution in terms of the number of equal width black and white lines per millimetre that
can be resolved according to some criterion, such as visual resolution or limiting resolution
[ISO 12233]
NOTE 1 Distance units other than millimetres may also be used.
NOTE 2 1 lp/mm = 2 lines/mm.
2.71
luminance factor
ratio of the luminance of the surface element in the given direction to that of a perfect reflecting or transmitting
diffuser identically illuminated
[CIE Publication 17.4 (845-04-69), ISO 17321-1, ISO 17321-2, ISO 22028-1]
cf. equivalent neutral luminance factor, luminance ratio
2.72
main image
primary (e.g. full resolution) image data
[ISO 12234-3]
2.73
maximum exposure limit
smallest exposure which produces the digital output level corresponding to the maximum detectable exposure
[ISO 14524]
cf. minimum exposure limit
NOTE The maximum detectable exposure is also known as the saturation or quantization ceiling.
2.74
media profile
portion of the memory module specification which is specific to a given memory technology; including the form
factor, interconnection and access protocol
[ISO 12234-1]
cf. image storage application profile, image data format
2.75
memory card
specific type of memory module with a physical form factor no larger than that of a credit card in outline, i.e.
approximately 85 mm × 55 mm
[ISO 12234-1]
2.76
memory module
physical implementation of the removable memory, containing the image data format combined with a
specified physical form factor, interconnect definition and access protocol
[ISO 12234-1]
2.77
minimum exposure limit
largest exposure below saturation which produces an incremental output signal equal in magnitude to the
output noise
[ISO 14524]
cf. incremental output signal, maximum exposure limit, output noise
2.78
modulation
difference between the minimum and maximum signal levels divided by the sum of these levels
[ISO 12233]
2.79
modulation transfer function
MTF
modulus of the optical transfer function
[ISO 12233]
cf. optical transfer function, spatial frequency response
12 © ISO 2005 – All rights reserved

2.80
noise
unwanted variations in the response of an imaging system
2.80.1
total noise
all the noise captured by a single exposure
2.80.2
fixed pattern noise
noise that is consistent for every exposure
2.80.3
temporally varying noise
random noise due to sensor dark current, photon shot noise, analogue processing, and quantization, that
varies from one image to the next
[ISO 15739, ISO 21550]
2.81
noise spectral power distribution
curve or equation that expresses the camera output noise as a function of two-dimensional image spatial
frequencies
[ISO 15739]
2.82
normalized spatial frequency
cycles
unit used for expressing spatial frequency response, where the distance dimension has been removed by
multiplying the spatial frequency in cycles per millimetre by the sampling period in millimetres
[ISO 12233]
NOTE Normalized spatial frequency is particularly appropriate for comparing the spatial frequency response of imaging
systems where the rendering magnification is unknown, and the total number of samples is equal.
2.83
Nyquist limit
spatial frequency equal to 0,5 times the inverse of the sampling period
[ISO 12233]
NOTE Energy at input spatial frequencies above the Nyquist limit will alias to a spatial frequency below the Nyquist limit
in the output image. The Nyquist limit may be different in the two orthogonal directions.
2.84
optical transfer function
OTF
two-dimensional Fourier transform of the imaging system's point spread function
[ISO 12233]
cf. modulation transfer function, spatial frequency response
NOTE For the OTF to have significance, it is necessary that the imaging system be operating in an isoplanatic region
and in its linear range. The OTF is a complex function whose modulus has unity value at zero spatial frequency.
2.85
opto-electronic conversion function
OECF
relationship between the log of the input levels and the corresponding digital output levels for an opto-
electronic digital image capture system
[ISO 14524]
NOTE If the input log exposure points are very finely spaced and the output noise is small compared to the quantization
interval, the OECF may have a step-like character. Such behaviour is an artefact of the quantization process and should
be removed by using an appropriate smoothing algorithm or by fitting a smooth curve to the data.
2.85.1
camera opto-electronic conversion function
camera OECF
relationship between the input scene log luminances and the digital output levels for an opto-electronic digital
image capture system
NOTE The units of measurement for this function are log candelas per square metre.
[ISO 14524, ISO 15739]
2.85.2
focal plane opto-electronic conversion function
focal plane OECF
relationship between the input focal plane log exposures (units: log lux seconds) and the digital output levels
for an opto-electronic digital image capture system
[ISO 14524]
2.86
opto-electronic digital image capture system
system which converts either a light exposure at the focal plane, or a spatial arrangement of luminances (a
scene) to digital information
[ISO 14524]
2.87
output noise
root-mean-square fluctuation about the mean in the digital output level for a constant input level
[ISO 14524]
2.88
PC
personal computer
[ISO 12234-3]
NOTE A PC can employ various hardware architectures and operating systems, and does not imply a specific type of
hardware, or operating system.
2.89
photography
acquisition, processing or reproduction of optically-formed images using chemical or electronic technologies
14 © ISO 2005 – All rights reserved

2.90
photosite integration time
total time period during which the photosites of an image sensor are able to integrate the light from the scene
to form an image
[ISO 12232, ISO 15739]
2.91 Picture formats formed by video signals
2.91.1
field
〈interlaced video〉 assembly of alternate (odd or even) lines of a frame
NOTE 1 An interlaced frame is composed of two fields: an odd field and an even field, representing the odd- and even-
numbered lines respectively.
NOTE 2 Adapted from ISO/IEC 13818-2:1996
2.91.2
frame(1)
〈progressive video〉 lines of spatial information of a video signal, containing samples starting from one time
instant and continuing through successive lines to the bottom of the frame
NOTE Adapted from ISO/IEC 13818-2:1996
2.91.3
frame(2)
〈interlaced video〉 lines of spatial information of a video signal, consisting of an odd field and an even field; one
of which will commence one field period later than the other
NOTE Adapted from ISO/IEC 13818-2:1996
2.91.4
movie frame
studio frame
〈interlaced video〉 frame consisting of two fields taken simultaneously
2.92
play
display an image or output an image as a hard copy
[ISO 12234-3]
2.93
point spread function
PSF
normalized spatial signal distribution in the linearized output of an imaging system resulting from imaging a
theoretical infinitely small point source
[ISO 12233]
2.94
protection
setting the ReadOnly attribute for a DCF object or directory
[ISO 12234-3]
2.95
Reader 1
playback device function that meets the requirements of the DCF Reader 1 specification
[ISO 12234-3]
2.96
Reader 2
playback device function that meets the requirements of the DCF Reader 2 specification
[ISO 12234-3]
2.97
removable memory
storage in a user-removable form factor, which is transportable and intended for the digital storage of image
data in electronic still cameras
[ISO 12234-1]
NOTE The memory media may be read/write, write once, etc. but must be non-volatile; when removed from the camera,
it must retain the data.
2.98
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
[ISO 12233, ISO 16067-1, ISO 16067-2, ISO 21550]
NOTE Resolution measurement metrics include resolving power, visual resolution, limiting resolution, SFR, MTF and
OTF.
2.99
sample spacing
physical distance between sampling points or sampling lines
[ISO 12233, ISO 16067-1, ISO 16067-2, ISO 21550]
NOTE The sample spacing may be different in the two orthogonal sampling directions.
2.100
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
[ISO 12233, ISO 16067-1, ISO 16067-2, ISO 21550]
NOTE The sampling at each point is done using a finite-size sampling aperture or area.
2.101
sampling aspect ratio
ratio of the sample spacing in the two orthogonal sampling directions
[ISO 12233]
NOTE If the sample spacing is equal, the aspect ratio of the sampling grid is 1:1, or “square”, so that the sampling
aspect ratio provides “square pixels".
16 © ISO 2005 – All rights reserved

2.102
sampling frequency
reciprocal of the sample spacing
[ISO 16067-1, ISO 16067-2, ISO 21550]
NOTE The sampling frequency is expressed in samples per unit distance.
2.103
scanner
electronic device that converts a fixed image, such as a print or film transparency, into an electronic signal
[ISO 16067-1, ISO 16067-2, ISO 21550]
2.104
scanner opto-electronic conversion function
scanner OECF
relationship between the input density and the digital output levels for an opto-electronic digital image capture
system
[ISO 16067-1, ISO 16067-2, ISO 21550]
2.105
scene luminance ratio
ratio of the highest (highlight) luminance value to the lowest (shadow) luminance value in a scene
[ISO 14524]
2.106
signal processing
operations performed by electronic circuits or algorithms that convert or modify the output of an image sensor
[ISO 12232, ISO 15739]
2.107
slow scan direction
direction in which the scanner moves the photoelements (perpendicular to the lines of active photoelements in
a linear array image sensor)
[ISO 16067-1, ISO 16067-2, ISO 21550]
2.108
softcopy
representation of an image produced using a device capable of directly representing different digital images in
succession and in a non-permanent form
[ISO 3664, ISO 22028-1]
EXAMPLE A monitor.
2.109
sound recording
recording of the sound data relative to an image acquired by the electronic still camera
[ISO 12234-1]
NOTE 1 The sound recording may be made before, during, or after the time of the image acquisition.
NOTE 2 A sound recording attached to an electronic still picture is considered an annotation of the image, as
distinguished from a sound recording which is attached to and synchronized with motion pictures or video pictures.
2.110
spatial frequency response
SFR
measured amplitude response of an imaging system as a function of relative input spatial frequency
[ISO 12233, ISO 16067-1, ISO 16067-2, ISO 21550]
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. The SFR is normalized to yield a value of 1,0 at a spatial
frequency of 0.
2.111
spectrally neutral
spectrally non-selective
exhibiting reflective or transmissive characteristics which are constant over the wavelength range of interest
[ISO 12233, ISO 16067-1, ISO 16067-2, ISO 17321-1, ISO 17321-2, ISO 21550]
cf. effectively spectrally neutral
2.112
test chart
arrangement of test patterns designed to test particular aspects of an imaging system
[ISO 12233, ISO 16067-1, ISO 16067-2, ISO 21550]
2.113
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 2.113.1 to 2.113.3.
2.113.1
bi-tonal pattern
pattern that is spectrally neutral or effectively spectrally neutral, and 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.
2.113.2
grey scale pattern
pattern that is spectrally neutral or effectively spectrally neutral, and 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.
2.113.3
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.
[ISO 12233, ISO 16067-1, ISO 16067-2, ISO 21550]
18 © ISO 2005 – All rights reserved

2.114
thumbnail
small version of the main image, used for indexing
[ISO 12234-3]
2.115
time scale exposure series
series of exposures produced using a constant focal plane illuminance and a varying exposure time
[ISO 14524]
cf. illuminance scale exposure series
2.116
tristimulus value
amounts of the three reference colour stimuli, in a given trichromatic system, required to match the colour of
the stimulus considered
[CIE Publication 17.4 (845-03-22), ISO 17321-1, ISO 17321-2, ISO 22028-1]
cf. colour matching functions
2.117
vertical pixels
number of luminance pixels of image data in the sub-scanning (i.e. y-axis) direction
[ISO 12234-3]
2.118
vertical resolution
resolution value measured in the shorter image dimension, corresponding to the vertical direction for a
“landscape” image orientation, typically using a horizontally oriented test chart feature
[ISO 12233]
2.119
video signal-to-noise ratio
〈video systems〉 ratio of the maximum (peak) output signal level to the root mean square (rms) noise level
[ISO 15739]
NOTE 1 Typically expressed in decibels (dB).
NOTE 2 This term should not be used to express the noise in an electronic still imaging system.
2.120
visual resolution
spatial frequency at which the individual black and white lines of a test pattern reproduced on a display or print
can no longer be distinguished by human observers, 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
[ISO 12233]
2.121
white balance
adjustment of electronic still picture colour channel gains or image processing so that radiation with relative
spectral power distribution equal to that of the scene illumination source is rendered as a visual neutral
[ISO 14524]
2.122
writer
recording device function that meets the requirements of the DCF Writer specification
[ISO 12234-3]
20 © ISO 2005 – All rights reserved

Annex A
(informative)
Other terms and definitions
A.1 Rationale
Included in this annex are terms collected from standards that have not reached the enquiry stage. These
terms are more likely to change as the source documents progress. Where possible, the latest draft of the
source document should be reviewed to see if a more current definition is available. These terms and
definitions are provided in this International Standard to facilitate communication. Future revisions of this
International Standard will include updated terms and definitions consistent with the source documents at the
time the revision is prepared.
A.2 Terms and definitions
A.2.1
absolute colorimetric coordinates
tristimulus values, or other colorimetric coordinate derived from tristimulus values, where the numerical value
corresponds to the magnitude of the physical stimulus
[ISO 22028-1, ISO 17321-1, ISO 17321-2]
cf. tristimulus value
NOTE When CIE 1931 2° standard observer colour matching functions are used, the Y value corresponds to the
luminance, not the luminance factor (or some scaled value thereof).
A.2.2
adapted white
colour stimulus that an observer who is adapted to the viewing environment would judge to be perfectly
achromatic and to have a luminance factor of unity; i.e. have absolute colorimetric coordinates that an
observer would consider to be the perfect white diffuser
[ISO 22028-1, ISO 17321-1, ISO 17321-2]
cf. adopted white
NOTE The adapted white may vary within
...

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Photographie - Prises de vue électroniques - VocabulairePhotography - Electronic still picture imaging - Vocabulary37.040.01Fotografija na splošnoPhotography in general01.040.37Slikovna tehnologija (Slovarji)Image technology (Vocabularies)ICS:Ta slovenski standard je istoveten z:ISO 12231:2005SIST ISO 12231:2011en01-julij-2011SIST ISO 12231:2011SLOVENSKI
STANDARD
Reference number ISO 12231:2005(E)© ISO 2005
INTERNATIONAL STANDARD ISO12231Second edition2005-02-01Photography — Electronic still picture imaging — Vocabulary Photographie — Prises de vue électroniques — Vocabulaire
ISO 2005 The reproduction of the terms and definitions contained in this International Standard is permitted in teaching manuals, instruction booklets, technical publications and journals for strictly educational or implementation purposes. The conditions for such reproduction are: that no modifications are made to the terms and definitions; that such reproduction is not permitted for dictionaries or similar publications offered for sale; and that this International Standard is referenced as the source document. With the sole exceptions noted above, no other 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
iii Contents Page Foreword.iv Introduction.v 1 Scope.1 2 Terms and definitions.1 Annex A (informative)
Other terms and definitions.21 Bibliography.42 Alphabetical index.43
v Introduction Electronic still picture imaging concepts are drawn from traditional photography, electronics, video, and information technology. In some cases the concepts must be redefined to apply to electronic still picture imaging. For example, unlike traditional photography, measurements cannot be defined in terms of “film” or “sensitized material”, since images acquired by digital image capture devices are stored electronically and are not immediately exposed on film. The meaning of shutter and exposure time is also different for digital image capture devices, because an electronic imaging sensor typically has image acquisition characteristics that are different from those of film. The purpose of this vocabulary is to standardize the use and meaning of terms associated with electronic still picture imaging. It is organized alphabetically and follows natural (English) word order wherever possible. The source of most of the terms in this International Standard are the documents on electronic still picture imaging developed by ISO/TC 42/WG 18, and ISO/TC 42/JWG 20 and 23 (with ISO/TC 130). Definitions from some other TC 42 International Standards, e.g. flare, are also included for completeness. The ISO numbers provided in brackets following the definition reference documents listed in the bibliography that serve as the source of the definition. At the end of some definitions, other terms are listed (preceded by “cf.”) that are related to the term being defined. An alphabetical index is included at the end of the document. Terms from working drafts and committee drafts of standards under development within ISO/TC 42 (as of 15 August 2002) are provided in Annex A. These terms are more likely to change as the source documents progress. Definitions are provided in this International Standard to facilitate communication. Where possible, the latest draft of the source document should be reviewed to see if a more current definition is available. Future revisions of this International Standard will include updated terms and definitions consistent with the source documents at the time the revision is prepared.
INTERNATIONAL STANDARD ISO 12231:2005(E) © ISO 2005 – All rights reserved
1 Photography — Electronic still picture imaging — Vocabulary 1 Scope This International Standard defines terms used in electronic still picture imaging. Only terms related to electronic still picture imaging are included. These terms are relevant to the current tasks or are of general interest in electronic still picture imaging. 2 Terms and definitions 2.1 addressable photoelements number of active photoelements on an image sensor, which is equal to the number of active lines of photoelements times the number of active photoelements per line [ISO 12233, ISO 16067-1, ISO 16067-2, ISO 21550] NOTE The term resolution should not be used when referring to the addressable photoelements. It is possible that the addressable photoelements may be different for the different colour records of an image. When the signal values of the photoelements are digitized, the digitized code values may be referred to as picture elements, or pixels. 2.2 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 [ISO 12233, ISO 16067-1, ISO 16067-2, ISO 21550] NOTE These artefacts usually manifest themselves as moiré patterns in repetitive image features or as jagged stair-stepping at edge transitions. 2.3 aliasing ratio value equal to the “maximum minus minimum” modulation divided by the “average” modulation of an electronic still picture camera when imaging a frequency burst of constant spatial frequency [ISO 12233] 2.4 analog-to-digital converter A/D or ADC circuit that converts an analog signal, having a continuously varying amplitude, to a digitally quantized representation using binary output signals 2.5 application image application software for use on a personal computer [ISO 12234-3] SIST ISO 12231:2011

3 2.12 cycles per millimetre cy/mm unit used for specifying resolution characteristics in terms of the response of an imaging system to a linear radiance sine wave input, as a function of the frequency of the sine wave [ISO 12233] NOTE 1 A range of input sine wave frequencies is obtained in ISO 12233 through the use of a sharp edge target. NOTE 2 Most pictorial imaging systems exhibit non-linear behaviour, which may result in the nature of the target affecting the measured resolution characteristics. Distance units other than millimetres may also be used. 2.13 DCF design rule for camera file system design rules for camera file system as specified in ISO 12234-3 NOTE DCF provides a standard convention for camera file systems that specifies the file format, folders, and naming conventions in order to promote file interoperability between conforming digital still photography devices. 2.14 DCF basic file image file stored directly under a DCF directory, having a DCF filename and the extension “JPG” and having the DCF-defined data structure, based on the Exif standard [ISO 12234-3] 2.15 DCF basic main image Exif primary image included in a DCF basic file [ISO 12234-3] 2.16 DCF basic thumbnail Exif thumbnail image included in a DCF basic file [ISO 12234-3] 2.17 DCF-compatible meeting the requirements of ISO 12234-3 [ISO 12234-3] 2.18 DCF directory directory under the DCF image root directory for storing images, created in accordance with the DCF directory rules [ISO 12234-3] 2.19 DCF directory name directory name assigned in accordance with the DCF directory-naming conventions [ISO 12234-3] SIST ISO 12231:2011

5 2.29 directory number three-digit number which is comprised of the first three characters of the DCF directory name [ISO 12234-3] 2.30 edge spread function ESF normalized spatial signal distribution in the linearized output of an imaging system resulting from imaging a theoretical infinitely sharp edge [ISO 12233, ISO 16067-1, ISO 16067-2, ISO 21550] cf. line spread function, point spread function 2.31 effectively spectrally neutral having spectral characteristics which result in a specific imaging system producing the same output as for a spectrally neutral object [ISO 12233, ISO 16067-1, ISO 16067-2, ISO 21550] cf. spectrally neutral 2.32 electronic scanner(1) 〈photographic films〉 scanner incorporating an image sensor that outputs a digital signal representing a still film image [ISO 16067-2, ISO 21550] 2.33 electronic scanner(2) 〈photographic prints〉 scanner incorporating an image sensor that outputs a digital signal representing a still print image [ISO 16067-1] 2.34 electronic shutter any one of three devices for controlling the exposure time of an electronic still picture camera 2.34.1 electronically shuttered sensor component of an electronic still camera which electronically controls the image sensor itself in order to set the exposure time 2.34.2 electromechanical shutter mechanical shutter which is electronically controlled 2.34.3 electro-optical shutter electronically driven device in front of the image sensor which changes the optical path transmittance SIST ISO 12231:2011

acquisition of a picture by combining repeated exposures to capture different colour components NOTE Colour sequential exposure can be by means of three colour illuminations, or by three colour filters. 2.38.3 time sequential exposure
acquisition of a picture by combining repeated exposures to capture different spatial components NOTE Time sequential exposure can be with a line array (line scanning) or an area array. With a line array, the picture is acquired by optical or physical sub-scanning with an image sensor in one dimension. With an area array, repeated exposures may integrate smaller pictures into a larger picture by means of image sensor shifting. 2.39 exposure series series of images of the same subject taken using different exposure index values [ISO 12232] SIST ISO 12231:2011

7 2.40 fast scan direction scan direction corresponding to the direction of the alignment of the addressable photoelements in a linear array image sensor [ISO 16067-1, ISO 16067-2, ISO 21550] 2.41 file extension three identifying characters used in the DOS/FAT file system following the file name and dot [ISO 12234-3] 2.42 file name eight-character file name of the DOS/FAT file system, excluding the dot and file extension [ISO 12234-3] 2.43 file number four-digit number which comprises the last four characters of the DCF file name [ISO 12234-3] 2.44 file system software structure which specifies how the data are logically organized on a given storage medium [ISO 12234-1, ISO 12234-2] 2.45 flare light falling on an image, in an imaging system, which does not emanate from the subject point [ISO 3664] cf. veiling glare NOTE Veiling glare is also sometimes referred to as flare. 2.45.1 veiling flare relatively uniform but unwanted irradiation in the image plane of an optical system, caused by the scattering and reflection of a proportion of the radiation which enters the system through its normal entrance aperture [ISO 3664] NOTE 1 The veiling flare radiation may be from inside or outside the field of view of the system. NOTE 2 Light leaks in an optical system housing can cause additional unwanted irradiation of the image plane. This irradiation may resemble veiling flare. 2.46 free characters five characters following the directory number in a DCF directory name, or the four characters at the beginning of a DCF file name [ISO 12234-3] SIST ISO 12231:2011

9 2.54 image storage application profile ISAP media profile plus the image data format [ISO 12234-1] NOTE The ISAP specifies all the information necessary to completely implement the removable memory. 2.55 imager size 〈area array sensor〉 physical dimensions, in height and width, of the photoresponsive area of an imaging sensor NOTE The following addition is adapted from EIAJ EDX-5301: The measure of imager size for a video-based still picture camera is described by the approximate diameter of a tube-type image sensor which is equivalent to a diagonal length of the solid-state image sensor. The expressions of diameters of 2/3, 1/2, 1/3 or 1/4 inch (type) correspond to actual imager sizes of 6,6 mm × 8,8 mm, 4,8 mm × 6,4 mm, 3,6 mm × 4,8 mm, and 2,7 mm × 3,6 mm respectively, for 4:3 image aspect ratio sensors. 2.56 incremental gain function change in the output level (digital code value) divided by the change in the input level (luminance or exposure) as a function of input level [ISO 14524, ISO 15739, ISO 21550] NOTE 1 For the determination of incremental gain values, log input values are not used. NOTE 2 If the input exposure points are very finely spaced and the output noise is small compared to the quantization interval, the incremental gain function may have a jagged shape. Such behaviour is an artefact of the quantization process and should be removed by using an appropriate smoothing algorithm or by fitting a smooth curve to the data. In some cases it may be desirable to fit a curve to the input-output data and then determine the incremental gain function by taking the first derivative of the function used for the curve fit. 2.57 incremental output signal input level (luminance or exposure, not logged) multiplied by the system incremental gain at that level [ISO 14524, ISO 15739, ISO 21550] cf. incremental gain function 2.58 incremental signal-to-noise ratio ratio of the incremental output signal to the root mean square (rms) noise level, at a particular signal level [ISO 15739, ISO 21550] NOTE The incremental signal-to-noise ratio is typically expressed as a graph or table showing the rms noise level versus output signal level for the full range of output signal levels. 2.59 ISO DSC dynamic range ratio of the maximum luminance level that appears unclipped to the minimum luminance level that can be reproduced with an incremental signal-to-temporal-noise ratio of at least 1, as determined according to ISO 15739 [ISO 15739] SIST ISO 12231:2011

11 2.67 line spread function LSF normalized spatial signal distribution in the linearized output of an imaging system resulting from imaging a theoretical infinitely thin line [ISO 12233] NOTE If the imaging system is operating in an isoplanatic region and in its linear range, the LSF is equal to the first derivative of the ESF. 2.68 line widths per picture height LW/PH metric for specifying the width of a feature on a test chart, relative to the height of the active area of the chart, which is equal to the height of the active area of the test chart divided by the width of a black line that is equal to the total number of lines of the same width which can be placed edge to edge within the height of a test target or within the vertical field of view of a camera NOTE Adapted from ISO 12233. EXAMPLE If the height of the active area of the chart equals 20 cm, a black line of 1 000 LW/PH has a width equal to 20/1 000 cm. 2.69 linearized digital signal conversion performed to invert either the focal plane or the camera opto-electronic conversion function (OECF) so that the resulting signal is approximately linearly proportional to focal plane exposure or scene luminance, respectively [ISO 12233] 2.70 lines per millimetre lines/mm metric for specifying resolution in terms of the number of equal width black and white lines per millimetre that can be resolved according to some criterion, such as visual resolution or limiting resolution [ISO 12233] NOTE 1 Distance units other than millimetres may also be used. NOTE 2 1 lp/mm = 2 lines/mm. 2.71 luminance factor ratio of the luminance of the surface element in the given direction to that of a perfect reflecting or transmitting diffuser identically illuminated [CIE Publication 17.4 (845-04-69), ISO 17321-1, ISO 17321-2, ISO 22028-1] cf. equivalent neutral luminance factor, luminance ratio 2.72 main image primary (e.g. full resolution) image data [ISO 12234-3] SIST ISO 12231:2011

13 2.80 noise unwanted variations in the response of an imaging system 2.80.1 total noise all the noise captured by a single exposure 2.80.2 fixed pattern noise noise that is consistent for every exposure 2.80.3 temporally varying noise random noise due to sensor dark current, photon shot noise, analogue processing, and quantization, that varies from one image to the next [ISO 15739, ISO 21550] 2.81 noise spectral power distribution curve or equation that expresses the camera output noise as a function of two-dimensional image spatial frequencies [ISO 15739] 2.82 normalized spatial frequency cycles unit used for expressing spatial frequency response, where the distance dimension has been removed by multiplying the spatial frequency in cycles per millimetre by the sampling period in millimetres [ISO 12233] NOTE Normalized spatial frequency is particularly appropriate for comparing the spatial frequency response of imaging systems where the rendering magnification is unknown, and the total number of samples is equal. 2.83 Nyquist limit spatial frequency equal to 0,5 times the inverse of the sampling period [ISO 12233] NOTE Energy at input spatial frequencies above the Nyquist limit will alias to a spatial frequency below the Nyquist limit in the output image. The Nyquist limit may be different in the two orthogonal directions. 2.84 optical transfer function OTF two-dimensional Fourier transform of the imaging system's point spread function [ISO 12233] cf. modulation transfer function, spatial frequency response NOTE For the OTF to have significance, it is necessary that the imaging system be operating in an isoplanatic region and in its linear range. The OTF is a complex function whose modulus has unity value at zero spatial frequency. SIST ISO 12231:2011

15 2.90 photosite integration time total time period during which the photosites of an image sensor are able to integrate the light from the scene to form an image [ISO 12232, ISO 15739] 2.91 Picture formats formed by video signals 2.91.1 field 〈interlaced video〉 assembly of alternate (odd or even) lines of a frame NOTE 1 An interlaced frame is composed of two fields: an odd field and an even field, representing the odd- and even-numbered lines respectively. NOTE 2 Adapted from ISO/IEC 13818-2:1996 2.91.2 frame(1) 〈progressive video〉 lines of spatial information of a video signal, containing samples starting from one time instant and continuing through successive lines to the bottom of the frame NOTE Adapted from ISO/IEC 13818-2:1996 2.91.3 frame(2) 〈interlaced video〉 lines of spatial information of a video signal, consisting of an odd field and an even field; one of which will commence one field period later than the other NOTE Adapted from ISO/IEC 13818-2:1996 2.91.4 movie frame studio frame 〈interlaced video〉 frame consisting of two fields taken simultaneously 2.92 play display an image or output an image as a hard copy [ISO 12234-3] 2.93 point spread function PSF normalized spatial signal distribution in the linearized output of an imaging system resulting from imaging a theoretical infinitely small point source [ISO 12233] 2.94 protection setting the ReadOnly attribute for a DCF object or directory [ISO 12234-3] SIST ISO 12231:2011

17 2.102 sampling frequency reciprocal of the sample spacing [ISO 16067-1, ISO 16067-2, ISO 21550] NOTE The sampling frequency is expressed in samples per unit distance. 2.103 scanner electronic device that converts a fixed image, such as a print or film transparency, into an electronic signal [ISO 16067-1, ISO 16067-2, ISO 21550] 2.104 scanner opto-electronic conversion function scanner OECF relationship between the input density and the digital output levels for an opto-electronic digital image capture system [ISO 16067-1, ISO 16067-2, ISO 21550] 2.105 scene luminance ratio ratio of the highest (highlight) luminance value to the lowest (shadow) luminance value in a scene [ISO 14524] 2.106 signal processing operations performed by electronic circuits or algorithms that convert or modify the output of an image sensor [ISO 12232, ISO 15739] 2.107 slow scan direction direction in which the scanner moves the photoelements (perpendicular to the lines of active photoelements in a linear array image sensor) [ISO 16067-1, ISO 16067-2, ISO 21550] 2.108 softcopy representation of an image produced using a device capable of directly representing different digital images in succession and in a non-permanent form [ISO 3664, ISO 22028-1] EXAMPLE A monitor. 2.109 sound recording recording of the sound data relative to an image acquired by the electronic still camera [ISO 12234-1] NOTE 1 The sound recording may be made before, during, or after the time of the image acquisition. NOTE 2 A sound recording attached to an electronic still picture is considered an annotation of the image, as distinguished from a sound recording which is attached to and synchronized with motion pictures or video pictures. SIST ISO 12231:2011

19 2.114 thumbnail small version of the main image, used for indexing [ISO 12234-3] 2.115 time scale exposure series series of exposures produced using a constant focal plane illuminance and a varying exposure time [ISO 14524] cf. illuminance scale exposure series 2.116 tristimulus value amounts of the three reference colour stimuli, in a given trichromatic system, required to match the colour of the stimulus considered [CIE Publication 17.4 (845-03-22), ISO 17321-1, ISO 17321-2, ISO 22028-1] cf. colour matching functions 2.117 vertical pixels number of luminance pixels of image data in the sub-scanning (i.e. y-axis) direction [ISO 12234-3] 2.118 vertical resolution resolution value measured in the shorter image dimension, corresponding to the vertical direction for a “landscape” image orientation, typically using a horizontally oriented test chart feature [ISO 12233] 2.119 video signal-to-noise ratio 〈video systems〉 ratio of the maximum (peak) output signal level to the root mean square (rms) noise level [ISO 15739] NOTE 1 Typically expressed in decibels (dB). NOTE 2 This term should not be used to express the noise in an electronic still imaging system. 2.120 visual resolution spatial frequency at which the individual black and white lines of a test pattern reproduced on a display or print can no longer be distinguished by human observers, 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 [ISO 12233] SIST ISO 12231:2011

21 Annex A (informative)
Other terms and definitions A.1 Rationale Included in this annex are terms collected from standards that have not reached the enquiry stage. These terms are more likely to change as the source documents progress. Where possible, the latest draft of the source document should be reviewed to see if a more current definition is available. These terms and definitions are provided in this International Standard to facilitate communication. Future revisions of this International Standard will include updated terms and definitions consistent with the source documents at the time the revision is prepared. A.2 Terms and definitions A.2.1 absolute colorimetric coordinates tristimulus values, or other colorimetric coordinate derived from tristimulus values, where the numerical value corresponds to the magnitude of the physical stimulus [ISO 22028-1, ISO 17321-1, ISO 17321-2] cf. tristimulus value NOTE When CIE 1931 2° standard observer colour matching functions are used, the Y value corresponds to the luminance, not the luminance factor (or some scaled value thereof). A.2.2 adapted white colour stimulus that an observer who is adapted to the viewing environment would judge to be perfectly achromatic and to have a luminance factor of unity; i.e. have absolute colorimetric coordinates that an observer would consider to be the perfect white diffuser [ISO 22028-1, ISO 17321-1, ISO 17321-2] cf. adopted white NOTE The adapted white may vary within a scene. A.2.3 additive RGB colour space colorimetric colour space having three colour primaries (generally red, green and blue) such that CIE XYZ tristimulus values can be determined from the RGB colour space values by forming a weighted combination of the CIE XYZ tristimulus values for the individual colour primaries, where the weights are proportional to the radiometrically linear colour space values for the corresponding colour primaries [ISO 22028-1] NOTE 1 A simple linear 3 × 3 matrix transformation can be used to transform between CIE XYZ tristimulus values and the radiometrically linear colour space values for an additive RGB colour space. NOTE 2 Additive RGB colour spaces are defined by specifying the CIE chromaticity values for a set of additive RGB primaries and a colour space white point, together with a colour component transfer function. SIST ISO 12231:2011
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