SIST ISO 17321-1:2014
Graphic technology and photography - Colour characterisation of digital still cameras (DSCs) - Part 1: Stimuli, metrology and test procedures
Graphic technology and photography - Colour characterisation of digital still cameras (DSCs) - Part 1: Stimuli, metrology and test procedures
ISO 17321-1:2012 specifies colour stimuli, metrology, and test procedures for the colour characterization of a digital still camera (DSC) to be used for photography and graphic technology. Two methods are provided, one using narrow spectral band illumination and the other using a spectrally and colorimetrically calibrated target. Except for a specific set of permitted data operations, these DSC data are raw.
Technologie graphique et photographie - Caractérisation de la couleur des appareils photonumériques - Partie 1: Stimuli, métrologie et modes opératoires d'essai
Grafična tehnologija in fotografija - Barvna karakterizacija digitalnih kamer za mirujoče slike (DSC) - 1. del: Dražljaji, metrologija in preskusni postopki
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
01-marec-2014
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SIST ISO 17321-1:2011
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Graphic technology and photography - Colour characterisation of digital still cameras
(DSCs) - Part 1: Stimuli, metrology and test procedures
Technologie graphique et photographie - Caractérisation de la couleur des appareils
photonumériques - Partie 1: Stimuli, métrologie et modes opératoires d'essai
Ta slovenski standard je istoveten z: ISO 17321-1:2012
ICS:
01.070 Barvno kodiranje Colour coding
37.040.10 Fotografska oprema. Photographic equipment.
Projektorji Projectors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
INTERNATIONAL ISO
STANDARD 17321-1
Second edition
2012-11-01
Graphic technology and
photography — Colour
characterisation of digital still
cameras (DSCs) —
Part 1:
Stimuli, metrology and test procedures
Technologie graphique et photographie — Caractérisation de la
couleur des appareils photonumériques —
Partie 1: Stimuli, métrologie et modes opératoires d’essai
Reference number
©
ISO 2012
© ISO 2012
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 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 copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 DSC colour characterization methods . 2
4.1 General . 2
4.2 Spectral sensitivity-based characterization — Method A . 3
4.3 Target-based characterization — Method B . 4
Annex A (informative) Recommended laboratory set-up for photographing a reflection colour
test target . 8
Annex B (informative) Digital still camera/sensitivity metamerism index (DSC/SMI).10
Annex C (informative) Characterization target considerations .16
Annex D (informative) Calculating natural scene element responses from spectral
characterization data . .23
Bibliography .26
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 17321-1 was prepared by Technical Committee ISO/TC 42, Photography, in collaboration with
ISO/TC 130, Graphic technology.
This second edition cancels and replaces the first edition (ISO 17321-1:2006), of which it constitutes a
minor revision with the following changes:
— in 4.3.3.4.2, the typographical error “senor image area” was corrected to “sensor image area”;
— in B.2.6, a broken link to tools for non-linear optimization has been updated.
ISO 17321 consists of the following parts, under the general title Graphic technology and photography —
Colour characterization of digital still cameras (DSCs):
— Part 1: Stimuli, metrology and test procedures
— Part 2: Considerations for determining scene analysis transforms [Technical Report]
iv © ISO 2012 – All rights reserved
Introduction
The spectral responses of the colour analysis channels of digital still cameras (DSCs) do not, in general,
match those of a typical human observer, such as defined by the CIE standard colorimetric observer. Nor
do the responses of different DSCs ordinarily match each other. In characterizing DSCs, it is therefore
necessary to take account of the DSC spectral sensitivities, illumination, and encoding colour space.
This part of ISO 17321 will begin to address these considerations. This part of ISO 17321 defines stimuli
(spectral illumination or a colour target), metrology and photographic test procedures for acquiring
DSC characterization data. It specifies test procedures for “scenes”, the most general picture taking
conditions where metameric colours and a range of illumination sources are encountered. It also
specifies test procedures for hardcopy “originals”, a more narrowly defined picture-taking condition in
which the illumination source and the colorants being imaged are pre-defined.
ISO 17321 will distinguish among several possible image representations in different colour encodings
as depicted in Figure 1 which shows the diagram of a generic image workflow for digital photography.
Figure 1 — Generic image workflow for digital photography
The DSC characterizations obtained using this part of ISO 17321 will be applicable to raw (sensor-
referred) DSC data. Two alternative methods are described for obtaining these characterization data.
Method A, the spectral method, uses spectral lights as stimuli for measuring the colour performance
of a DSC. Method B, the target method, involves the use of a physical colour test target under specific
lighting conditions to measure DSC colour performance. Annexes A to C recommend a laboratory set-up
for photographing reflection targets, provide target patch selection criteria, and provide a digital still
camera metamerism index.
Some operations (colour pixel reconstruction, flare removal, white balancing) can be performed without
disqualifying the DSC data as being raw. However, operations that render the image data so that they
become output-referred (ready to display or to print) generally do disqualify the data. With such cameras,
this standard can only be applied if the capability exists to extract or to regenerate raw data, e.g. by applying
the inverse of the rendering transform or by tapping the appropriate signals internal to the camera.
The technical experts who have developed this part of ISO 17321 recognize that a standard that could
be applied generally to any (not just raw) DSC output would be desirable. Such a standard is problematic
for DSCs that employ colour-rendering algorithms in order to produce output-referred image data.
For such DSCs, it would frequently be impossible to determine if colour analysis errors relative to the
scene or original captured were due to sensor image encoding errors or to proprietary colour rendering
algorithms. The only way to make this distinction is if the colour rendering used is well documented and
available, and the rendered data can be converted to un-rendered data by inverting the colour rendering.
This situation is unlikely to occur because one of the major differentiators in DSC performance is the
colour rendering. Sophisticated colour-rendering algorithms can be image dependent, and locally varying
within an image. This makes it extremely difficult to reliably determine the exact colour rendering used
by analysing captured test scenes.
The purpose of this part of ISO 17321 is both to assist in the characterization of DSCs for colour
management purposes and to assist camera manufacturers in the determination of the colour analysis
capabilities of DSCs that they are developing. This standard is applicable to any DSC intended for
photographic or graphic technology applications. However, for many users it is not practical to apply
this part of ISO 17321 to individual DSCs. Some of the measurements described in this part of ISO 17321
require complex, expensive measurement equipment. In the case of test targets that are commercially
produced, spectral as well as colorimetric measurement data would ideally accompany the target.
Those unfamiliar with this part of ISO 17321 are encouraged to read through the entire standard (in
particular the informative annexes) before proceeding with DSC characterization, in order to verify
appropriateness for their particular application. In some cases, the procedures described in the
[5]
multimedia standard, IEC 61966-9 might be more applicable.
It is proposed that other parts of ISO 17321 will be developed in the future to deal with other aspects of
the colour characterization of digital still cameras.
vi © ISO 2012 – All rights reserved
INTERNATIONAL STANDARD ISO 17321-1:2012(E)
Graphic technology and photography — Colour
characterisation of digital still cameras (DSCs) —
Part 1:
Stimuli, metrology and test procedures
1 Scope
This part of ISO 17321 specifies colour stimuli, metrology, and test procedures for the colour
characterization of a digital still camera (DSC) to be used for photography and graphic technology. Two
methods are provided, one using narrow spectral band illumination and the other using a spectrally
and colorimetrically calibrated target. Except for a specific set of permitted data operations, these DSC
data are raw.
This part of ISO 17321 does not specify the methods for deriving transformations from raw DSC data in
order to estimate scene colorimetry.
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 7589, Photography — Illuminants for sensitometry — Specifications for daylight, incandescent
tungsten and printer
ISO 13655, Graphic technology — Spectral measurement and colorimetric computation for graphic arts images
ISO 14524:2009, Photography — Electronic still-picture cameras — Methods for measuring opto-electronic
conversion functions (OECFs)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
adopted white
spectral radiance distribution as seen by an image capture or measurement device and converted to
colour signals that are considered to be perfectly achromatic and to have an observer adaptive luminance
factor of unity; i.e. colour signals that are considered to correspond to a perfect white diffuser
[ISO 22028-1]
NOTE 1 The adopted white can vary within a scene.
NOTE 2 No assumptions can be made concerning the relation between the adapted or adopted white and
measurements of near perfectly reflecting diffusers in a scene, because measurements of such diffusers will
depend on the illumination and viewing geometry, and other elements in the scene that can affect perception.
3.2
digital still camera
DSC
device that incorporates an image sensor and that produces a digital signal representing a still picture
NOTE A digital still c
...
INTERNATIONAL ISO
STANDARD 17321-1
Second edition
2012-11-01
Graphic technology and
photography — Colour
characterisation of digital still
cameras (DSCs) —
Part 1:
Stimuli, metrology and test procedures
Technologie graphique et photographie — Caractérisation de la
couleur des appareils photonumériques —
Partie 1: Stimuli, métrologie et modes opératoires d’essai
Reference number
©
ISO 2012
© ISO 2012
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 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 copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 DSC colour characterization methods . 2
4.1 General . 2
4.2 Spectral sensitivity-based characterization — Method A . 3
4.3 Target-based characterization — Method B . 4
Annex A (informative) Recommended laboratory set-up for photographing a reflection colour
test target . 8
Annex B (informative) Digital still camera/sensitivity metamerism index (DSC/SMI).10
Annex C (informative) Characterization target considerations .16
Annex D (informative) Calculating natural scene element responses from spectral
characterization data . .23
Bibliography .26
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 17321-1 was prepared by Technical Committee ISO/TC 42, Photography, in collaboration with
ISO/TC 130, Graphic technology.
This second edition cancels and replaces the first edition (ISO 17321-1:2006), of which it constitutes a
minor revision with the following changes:
— in 4.3.3.4.2, the typographical error “senor image area” was corrected to “sensor image area”;
— in B.2.6, a broken link to tools for non-linear optimization has been updated.
ISO 17321 consists of the following parts, under the general title Graphic technology and photography —
Colour characterization of digital still cameras (DSCs):
— Part 1: Stimuli, metrology and test procedures
— Part 2: Considerations for determining scene analysis transforms [Technical Report]
iv © ISO 2012 – All rights reserved
Introduction
The spectral responses of the colour analysis channels of digital still cameras (DSCs) do not, in general,
match those of a typical human observer, such as defined by the CIE standard colorimetric observer. Nor
do the responses of different DSCs ordinarily match each other. In characterizing DSCs, it is therefore
necessary to take account of the DSC spectral sensitivities, illumination, and encoding colour space.
This part of ISO 17321 will begin to address these considerations. This part of ISO 17321 defines stimuli
(spectral illumination or a colour target), metrology and photographic test procedures for acquiring
DSC characterization data. It specifies test procedures for “scenes”, the most general picture taking
conditions where metameric colours and a range of illumination sources are encountered. It also
specifies test procedures for hardcopy “originals”, a more narrowly defined picture-taking condition in
which the illumination source and the colorants being imaged are pre-defined.
ISO 17321 will distinguish among several possible image representations in different colour encodings
as depicted in Figure 1 which shows the diagram of a generic image workflow for digital photography.
Figure 1 — Generic image workflow for digital photography
The DSC characterizations obtained using this part of ISO 17321 will be applicable to raw (sensor-
referred) DSC data. Two alternative methods are described for obtaining these characterization data.
Method A, the spectral method, uses spectral lights as stimuli for measuring the colour performance
of a DSC. Method B, the target method, involves the use of a physical colour test target under specific
lighting conditions to measure DSC colour performance. Annexes A to C recommend a laboratory set-up
for photographing reflection targets, provide target patch selection criteria, and provide a digital still
camera metamerism index.
Some operations (colour pixel reconstruction, flare removal, white balancing) can be performed without
disqualifying the DSC data as being raw. However, operations that render the image data so that they
become output-referred (ready to display or to print) generally do disqualify the data. With such cameras,
this standard can only be applied if the capability exists to extract or to regenerate raw data, e.g. by applying
the inverse of the rendering transform or by tapping the appropriate signals internal to the camera.
The technical experts who have developed this part of ISO 17321 recognize that a standard that could
be applied generally to any (not just raw) DSC output would be desirable. Such a standard is problematic
for DSCs that employ colour-rendering algorithms in order to produce output-referred image data.
For such DSCs, it would frequently be impossible to determine if colour analysis errors relative to the
scene or original captured were due to sensor image encoding errors or to proprietary colour rendering
algorithms. The only way to make this distinction is if the colour rendering used is well documented and
available, and the rendered data can be converted to un-rendered data by inverting the colour rendering.
This situation is unlikely to occur because one of the major differentiators in DSC performance is the
colour rendering. Sophisticated colour-rendering algorithms can be image dependent, and locally varying
within an image. This makes it extremely difficult to reliably determine the exact colour rendering used
by analysing captured test scenes.
The purpose of this part of ISO 17321 is both to assist in the characterization of DSCs for colour
management purposes and to assist camera manufacturers in the determination of the colour analysis
capabilities of DSCs that they are developing. This standard is applicable to any DSC intended for
photographic or graphic technology applications. However, for many users it is not practical to apply
this part of ISO 17321 to individual DSCs. Some of the measurements described in this part of ISO 17321
require complex, expensive measurement equipment. In the case of test targets that are commercially
produced, spectral as well as colorimetric measurement data would ideally accompany the target.
Those unfamiliar with this part of ISO 17321 are encouraged to read through the entire standard (in
particular the informative annexes) before proceeding with DSC characterization, in order to verify
appropriateness for their particular application. In some cases, the procedures described in the
[5]
multimedia standard, IEC 61966-9 might be more applicable.
It is proposed that other parts of ISO 17321 will be developed in the future to deal with other aspects of
the colour characterization of digital still cameras.
vi © ISO 2012 – All rights reserved
INTERNATIONAL STANDARD ISO 17321-1:2012(E)
Graphic technology and photography — Colour
characterisation of digital still cameras (DSCs) —
Part 1:
Stimuli, metrology and test procedures
1 Scope
This part of ISO 17321 specifies colour stimuli, metrology, and test procedures for the colour
characterization of a digital still camera (DSC) to be used for photography and graphic technology. Two
methods are provided, one using narrow spectral band illumination and the other using a spectrally
and colorimetrically calibrated target. Except for a specific set of permitted data operations, these DSC
data are raw.
This part of ISO 17321 does not specify the methods for deriving transformations from raw DSC data in
order to estimate scene colorimetry.
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 7589, Photography — Illuminants for sensitometry — Specifications for daylight, incandescent
tungsten and printer
ISO 13655, Graphic technology — Spectral measurement and colorimetric computation for graphic arts images
ISO 14524:2009, Photography — Electronic still-picture cameras — Methods for measuring opto-electronic
conversion functions (OECFs)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
adopted white
spectral radiance distribution as seen by an image capture or measurement device and converted to
colour signals that are considered to be perfectly achromatic and to have an observer adaptive luminance
factor of unity; i.e. colour signals that are considered to correspond to a perfect white diffuser
[ISO 22028-1]
NOTE 1 The adopted white can vary within a scene.
NOTE 2 No assumptions can be made concerning the relation between the adapted or adopted white and
measurements of near perfectly reflecting diffusers in a scene, because measurements of such diffusers will
depend on the illumination and viewing geometry, and other elements in the scene that can affect perception.
3.2
digital still camera
DSC
device that incorporates an image sensor and that produces a digital signal representing a still picture
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.
3.3
opto-electronic conversion function
OECF
relationship between log of input levels and corresponding digital output levels for an opto-electronic
digital image capture system
NOTE If the input log exposure points are very finely spaced and the output noise is small compared to
the quantization interval, the OECF possibly has a step-like character. Such behaviour is an artefact of the
quantization process and needs to be removed by using an appropriate smoothing algorithm or by fitting a
smooth curve to the data.
3.4
raw DSC image data
image data produced by, or internal to, a DSC that has not been processed, except for A/D conversion and
the following optional steps:
— linearization,
— dark current/frame subtraction,
— shading and sensitivity (flat field) correction,
— flare removal,
— white balancing (e.g. so the adopted white produces equal RGB values or no chrominance),
— missing colour pixel reconstruction (without colour transformations)
3.5
spectrally non-selective
exhibiting reflective or tr
...
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