ISO 12640-3:2007

Graphic technology - Prepress digital data exchange - Part 3: CIELAB standard colour image data (CIELAB/SCID)

ISO 12640-3:2007 specifies a set of standard large gamut colour images (encoded as 16-bit CIELAB digital data) that can be used for the evaluation of changes in image quality during coding, image processing (including transformation, compression and decompression), displaying on a colour monitor and printing. These images can be used for research, testing and assessing of output systems such as printers, colour management systems and colour profiles.

Technologie graphique — Échange de données numériques de préimpression — Partie 3: Données d'images en couleur normalisées CIELAB (CIELAB/SCID)

Grafična tehnologija – Izmenjava digitalnih podatkov v grafični pripravi – 3. del: Standardni podatki CIELAB za barvne slike (CIELAB/SCID)

General Information

• Status: Withdrawn
• Publication Date: 02-Jul-2007
• ICS: 35.240.30 - IT applications in information, documentation and publishing
• ICS: 37.100.99 - Other standards related to graphic technology
• Technical Committee: ISO/TC 130 - Graphic technology
• Drafting Committee: ISO/TC 130/WG 2 - Prepress data exchange
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 12-Aug-2022
• Completion Date: 13-Dec-2025
• Ref Project: SIST ISO 12640-3:2008 - Graphic technology - Prepress digital data exchange - Part 3: CIELAB standard colour image data (CIELAB/SCID)

Relations

• Revised: ISO 12640-3:2022 - Graphic technology - Prepress digital data exchange - Part 3: CIELAB standard colour image data (CIELAB/SCID)
• Effective Date: 06-Jun-2022

Standards Content (Sample)

SLOVENSKI STANDARD
01-januar-2008
*UDILþQDWHKQRORJLMD±,]PHQMDYDGLJLWDOQLKSRGDWNRYYJUDILþQLSULSUDYL±GHO
6WDQGDUGQLSRGDWNL&,(/$%]DEDUYQHVOLNH&,(/$%6&,'
Graphic technology - Prepress digital data exchange - Part 3: CIELAB standard colour
image data (CIELAB/SCID)
Ta slovenski standard je istoveten z: ISO 12640-3:2007
ICS:
35.240.30 Uporabniške rešitve IT v IT applications in information,
informatiki, dokumentiranju in documentation and
založništvu publishing
37.100.99 'UXJLVWDQGDUGLY]YH]L] Other standards related to
JUDILþQRWHKQRORJLMR graphic technology
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

SLOVENSKI STANDARD
01-januar-2008
*UDILþQDWHKQRORJLMD±,]PHQMDYDGLJLWDOQLKSRGDWNRYYJUDILþQLSULSUDYL±GHO
6WDQGDUGQLSRGDWNL&,(/$%]DEDUYQHVOLNH&,(/$%6&,'
Graphic technology - Prepress digital data exchange - Part 3: CIELAB standard colour
image data (CIELAB/SCID)
Ta slovenski standard je istoveten z: ISO 12640-3:2007
ICS:
35.240.30 Uporabniške rešitve IT v IT applications in information,
informatiki, dokumentiranju in documentation and
založništvu publishing
37.100.01 *UDILþQDWHKQRORJLMDQD Graphic technology in
VSORãQR general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 12640-3
First edition
2007-07-15
Graphic technology — Prepress digital
data exchange —
Part 3:
CIELAB standard colour image data
(CIELAB/SCID)
Technologie graphique — Échange de données numériques de
préimpression —
Partie 3: Données d'images en couleur normalisées CIELAB
(CIELAB/SCID)
Reference number
©
ISO 2007
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©  ISO 2007
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.
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Published in Switzerland
ii © ISO 2007 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Requirements . 2
5 Data description and definition. 3
5.1 Data set definition. 3
5.2 Colour encoding used in this part of ISO 12640. 3
5.3 Natural images . 4
5.4 Synthetic images . 7
6 Electronic data . 11
6.1 Image file characteristics. 11
6.2 Image file formats . 11
Annex A (normative) Guidance for use of digital data. 12
Annex B (informative) Definition of the reference colour gamut . 14
Annex C (normative) Check-sum data . 21
Annex D (informative) Typical TIFF file headers used for image data. 22
Annex E (informative) Text insertion. 24
Annex F (informative) Histogram and gamut plots. 25
Annex G (informative) CIELAB values in colour charts . 29
Bibliography . 33

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 12640-3 was prepared by Technical Committee ISO/TC 130, Graphic technology.
ISO 12640 consists of the following parts, under the general title Graphic technology — Prepress digital data
exchange:
⎯ Part 1: CMYK standard colour image data (CMYK/SCID)
⎯ Part 2: XYZ/sRGB encoded standard colour image data (XYZ/SCID)
⎯ Part 3: CIELAB standard colour image data (CIELAB/SCID)
The following parts are under preparation:
⎯ Part 4: Wide gamut display-referred standard colour image data (TBDencoded/SCID)
⎯ Part 5: Scene-referred standard colour image data (RIMM/SCID)

iv © ISO 2007 – All rights reserved

Introduction
0.1 Need for standard digital test images
Standard test images provide a set of data that can be used for any of the following tasks:
⎯ evaluating the colour reproduction of imaging systems;
⎯ evaluating colour image output devices;
⎯ evaluating the effect of image processing algorithms applied to the images;
⎯ evaluating the coding technologies necessary for the storage and transmission of high-definition image
data.
Because they exist as standard, well-defined, high-quality image data sets, typical of the range of image
content commonly encountered, they enable users to be confident that the images will produce good quality
reproductions, if properly rendered, and that they provide a reasonable test of the evaluation task being
undertaken. No limited set of images can fully test any system, but the sets provided give as reasonable a test
as can be expected from a limited image set. Furthermore, the existence of a standard image data set
enables users in different locations to produce comparisons without the need to exchange images prior to
reproduction.
However, different applications require that the standard image data be provided in different image states
using different image encodings (see ISO 22028-1). The user needs to select those appropriate to the
evaluation task being undertaken. Whilst transformation of the image data to another image state is always
possible, there is, in general, no agreement amongst experts as to how this is best done. Thus, it has been
considered preferable to provide data in three different image states in the various parts of ISO 12640.
Part 1 of ISO 12640 provides a set of 8-bits-per-channel data that is defined in terms of CMYK dot
percentages. The colours resulting from reproduction of CMYK data are strictly defined only at the time of
printing and, as such, the data are only applicable to evaluation of CMYK printing applications.
Transformations to other image states and colour encodings are not necessarily well defined. In fact, the data
might not even be useful for CMYK printing processes different from those typically found in traditional graphic
arts applications as the image data are defined to produce “pleasing” images when reproduced on systems
using “typical” inks and producing “typical” tone value rendering. Printing systems that use inks of a distinctly
different colour, or produce a very different tone value rendering, will not reproduce them as pleasing images
without a well-defined colour transformation. Moreover, with a bit depth of only 8 bits per channel, any colour
transformation employed will probably introduce artefacts.
Part 2 of ISO 12640 provides a set of test image data encoded both as XYZ tristimulus values with a depth of
16 bits per channel and as sRGB (defined in IEC 61966-2-1) with a bit depth of 8 bits per channel. (The higher
bit depth for the XYZ encoding is necessary because of the perceptual non-uniformity of the XYZ colour
space.) Both sets of data are optimized for viewing on a reference sRGB CRT display in the reference sRGB
viewing environment, and relative to CIE standard illuminant D65 for which the XYZ values were computed.
The images are mainly designed to be used on systems utilizing sRGB as the reference encoding, and as
such are mainly applicable to the consumer market and those systems for which the colour monitor is the
“hub” device. Although such systems are used for some applications in the graphic arts industry, sRGB is by
no means the most common image encoding. Furthermore, a particular drawback is the fact that the sRGB
colour gamut is quite different in shape than the colour gamut of typical offset printing. This difference can
necessitate fairly aggressive colour re-rendering to produce optimal prints from sRGB image data.
In order to be useful for applications where large, print-referred output gamuts are encountered, common in
graphic technology and photography, it was felt that it would be desirable to produce an image set in which
some colours are permitted to be encoded close to the boundary of the full colour gamut attainable with
surface colours. Furthermore, from the perspective of colour management it is advantageous if the images are
referenced to illuminant D50, which is the predominant reference illuminant used in graphic arts and
photography, both for viewing and measurement. For this reason it has also become the predominant
reference illuminant for most colour management applications.
The purpose of this part of ISO 12640 is, therefore, to provide a test image data set with a large colour gamut
related to illuminant D50. The bit depth of the natural images is 16 bits per channel, while the colour charts
and vignettes are 8 bits per channel.
0.2 Definition of the reference colour gamut
The reference colour gamut defined for this part of ISO 12640 originated from three quite separate sources.
However, it was noted that there was considerable similarity between the three. One definition came from
work within ISO/TC 130 itself, and this arose by consideration of various sets of published data, which
together were taken to define the colour gamut of surface colours. The other definitions arose from work within
Hewlett-Packard, which was focused on the colour gamuts obtainable by printing, and that of a group of
German photographic printing experts. The similarity of these led to the conclusion that it would be desirable
to reconcile them into a single gamut that would be taken as the reference colour gamut for this part of
ISO 12640. Full details of the reference colour gamut and its derivation are given in Annex B.
0.3 Characteristics of the test images
The performance of any colour reproduction system is normally evaluated both subjectively (by viewing the
final output image) and objectively (by measurement of control elements). This requirement dictated that the
test images include both natural scenes (pictures) and synthetic images (colour charts and colour vignettes).
Because the results of subjective image evaluation are strongly affected by the image content, it was
important to ensure that the natural images were of high quality and contained diverse subject matter.
However, by requiring images to look natural, it is difficult within a single, relatively small sample set to
produce elements in the scene that contain the subtle colour differences required in such test images and that
cover the full reference colour gamut defined. It is also important to have some images that contain subtle
differences in near-neutral colours. Thus, while most images contain colours that extend to the gamut
boundary, this is often only for a limited range of hues in each image. The full reference colour gamut can only
be explored by utilizing the synthetic colour chart.
A survey was conducted of all ISO/TC 130 member countries to identify desirable image content and to solicit
submission of suitable images for consideration. The image set that resulted consists of eight natural images,
eight colour charts and two colour vignettes. The natural images include flesh tones, images with detail in the
extreme highlights or shadows, neutral colours, brown and wood-tone colours that are often difficult to
reproduce, memory colours, complicated geometric shapes, fine detail, and highlight and shadow vignettes.
The colour charts and colour vignettes show the reference colour gamut (in CIE Lab colour space) in
cross-sections for 16 and 8 hue angles, respectively.
0.4 File format of the digital test images
* * *
All of the images consist of pixel interleaved data (L then a then b ) with the data origin at the upper left of the
image, as viewed naturally, and organized by rows. These data are available as individual files, which are a
normative part of this part of this part of ISO 12640. The image file format is as specified in ISO 12639:2004,
Annex H, with BitsPerSample set to 16, 16, 16. The images can be imported and manipulated as necessary
by a wide variety of imaging software tools and platforms commonly in general use in the industry. (See
Annex D for details of the TIFF header.)
All colour charts and vignettes consist of files in Adobe® PDF format.

vi © ISO 2007 – All rights reserved

INTERNATIONAL STANDARD ISO 12640-3:2007(E)

Graphic technology — Prepress digital data exchange —
Part 3:
CIELAB standard colour image data (CIELAB/SCID)
1 Scope
This part of ISO 12640 specifies a set of standard large gamut colour images (encoded as 16-bit CIELAB
digital data) that can be used for the evaluation of changes in image quality during coding, image processing
(including transformation, compression and decompression), displaying on a colour monitor and printing.
These images can be used for research, testing and assessing of output systems such as printers, colour
management systems and colour profiles.
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 3664, Viewing conditions — Graphic technology and photography
ISO 12639:2004, Graphic technology — Prepress digital data exchange — Tag image file format for image
technology (TIFF/IT)
ISO 13655, Graphic technology — Spectral measurement and colorimetric computation for graphic arts
images
ISO 22028-1, Photography and graphic technology — Extended colour encodings for digital image storage,
manipulation and interchange — Part 1: Architecture and requirements
CIE Publication 15:2004, Colorimetry
ICC.1:2004-04, Image technology colour management — Architecture, profile format, and data structure
TIFF, Revision 6.0 Final, Aldus Corporation (now Adobe Systems Incorporated), June 3, 1992
PDF Reference: Adobe Portable Document Format, Version 1.4 3rd edn., Adobe Systems Incorporated,
(ISBN 0-201-75839-3)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
check sum
sum of the digits in a file that can be used to check if a file has been transferred properly
NOTE Often, only the least significant bits are summed.
3.2
colour gamut
solid in a colour space, consisting of all those colours that are present in a specific scene, artwork, photograph,
photomechanical or other reproduction; or are capable of being created using a particular output device and/or
medium
[ISO 12231]
3.3
colour sequence
order in which the colours are stored in a data file
3.4
colour space
geometric representation of colours in space, usually of three dimensions
[CIE Publication 17-1987 (845-03-25)]
3.5
colour value
numeric values associated with each of the pixels
3.6
data range
range of integers for a given variable in between a minimal and maximal value
3.7
global colour change
change to the colours in an image (often selectively by colour region) applied consistently to all parts of the
image
NOTE This is in contrast to a local colour change where selected spatial areas of an image are changed separately
from the rest of the image area.
3.8
orientation
specifies the origin and direction of the first line of data with respect to the image content as viewed by the end
user
NOTE The codes used to specify orientation are contained in ISO 12639:2004.
3.9
pixel
smallest discrete picture element in a digital image file
3.10
pixel interleaving
* * *
colour data organized such that the L , a and b colour space values for one pixel are followed by the same
sequence of colour values for the next pixel; the specific order of colour components is determined by the
ColorSequence tag as defined in ISO 12639
NOTE Other forms of colour data interleaving are line and plane.
4 Requirements
This part of ISO 12640 consists of the images contained in the 18 image data files which are part of this part
of ISO 12640. Their file names are listed in Table 4. The image characteristics of these data are described in
Clause 5 and the electronic data structure in Clause 6.
2 © ISO 2007 – All rights reserved

5 Data description and definition
5.1 Data set definition
The set of standard colour image data consists of eight natural (photographed) images and ten synthetic
images created digitally on a computer. The synthetic images consist of eight colour charts consisting of
various patches, each 10 mm square, and two colour vignettes. The natural images are identified as N1 to N8,
and each of them also has a descriptive name derived from the picture content (e.g. bride and groom). The
synthetic images are identified as CC1 to CC8, CV1 and CV2.
The images are identified by the designation CIELAB/SCID. The co-ordinates of the text insertion are provided
in Annex E.
NOTE The image set defined in this part of ISO 12640 is based on the large gamut defined in Annex B. Image sets
contained in other parts of ISO 12640 are based on different gamuts and can be more suitable for use in evaluation of
other applications.
5.2 Colour encoding used in this part of ISO 12640
5.2.1 Image data encoding
The image data encoding is defined in accordance with ISO 22028-1 requirements as follows.
The image data are the desired CIELAB colorimetry as defined by CIE Publication 15, and measured in
accordance with ISO 13655, of reproductions of the images on the reference medium, with the reference
medium white point selected as the colour space white point. The image data are output-referred, having been
rendered to the reference medium of the ICC.1:2004-04 perceptual rendering intent, which is defined as a
hypothetical print on a substrate specified to have a neutral reflectance of 89 % (the reference medium white
point) and the darkest printable colour on this medium is assumed to have a neutral reflectance of 0,347 31 %
of the substrate reflectance (the reference medium black point). The rendering target colour gamut for the
reference medium is specified in Annex B. The reference viewing environment is based on standard viewing
condition P2, as specified for graphic arts and photography in ISO 3664, but extended in the following way:
the surfaces immediately surrounding the image are assumed to be a uniform matt grey with a reflectance of
20 %. The reference viewing environment is also assumed to have a viewing flare of 0,75 % of the luminance
of the reference white. The CIELAB image data are encoded as specified in 5.2.3 and 5.2.4.
5.2.2 Image data arrangement
* * *
The image data are pixel-interleaved in the colour sequence of L then a then b (16 bits) for the natural
* * *
images and L then a then b (8 bits) for the colour charts and the vignettes. The arrangement of data follows
the scanning of each image from the upper left corner to the upper right, then moving to the next lower
horizontal line. The resolution is 12 pixels/mm for every natural image.
5.2.3 CIELAB image data (16 bits per channel)
The CIELAB data for the natural images are encoded as 16-bit integers per channel, derived by multiplying
* * *
the L , a and b values for each pixel with the corresponding value for the data range.
*
⎛⎞
L
*
L=×round⎜⎟65 535
16bit
⎜⎟
⎝⎠
**
aa=×round (256 ) (1)
16bit
**
bb=×round (256 )
16bit
* * * * * *
where L , a and b represent normalised 16-bit values of L , a and b .
16bit 16bit 16bit
The data range of the values is:
* * *
L ∈{0.100}, a ∈{−128.+127} and b ∈{−128.+127},
* * * * *
L ∈{0.65 535}, a ∈{−32 768.+32 512} and b ∈{−32 768.+32 512}, a and b are signed
16bit 16bit 16bit 16bit 16bit
integers.
NOTE −32 678 = −128 × 256, and 32 512 = 127 × 256.
5.2.4 CIELAB image data (8 bits per channel)
*
The CIELAB data for the colour charts are encoded as 8-bit integers per channel, derived by multiplying the L ,
* *
a and b values for each pixel with the corresponding value for the data range.
*
⎛⎞
L
*
L=×round⎜⎟255
8bit
⎜⎟
⎝⎠
**
aa= round ( ) (2)
8bit
**
bb= round ( )
8bit
* * * * * *
where L , a and b represent normalised 8 bit values of L , a and b .
8bit 8bit 8bit
The data range of the values is:
* * *
L ∈{0.100}, a ∈{−128.+127} and b ∈{−128.+127},
* * * * *
L ∈{0.255}, a ∈{−128.+127} and b ∈{−128.+127}, the a and b are signed integers.
8bit 8bit 8bit 8bit 8bit
5.3 Natural images
The characteristics of the eight natural images, shown in Figure 1, are given in Table 1.
Table 1 — Characteristics for natural images
Parameter Characteristics
Resolution 12 pixels/mm
* * *
16 bits/channel L , a and b , with respect to illuminant D50 (defined as
* * *
Colour values media-relative, i.e. such that a white in the image has the L , a and b values
of 100, 0, 0)
ISO 12639:2004, Annex H, with BitsPerSample set to 16, 16, 16
File format
This format also readable with TIFF 6.0 with extension, photometric
interpretation tag 8, CIELAB, signed encoding.
Label on image CIELAB/SCID
Image data orientation Horizontal scanning starting from top left and ending at bottom right

NOTE The natural images have been colour-rendered to produce the desired image colorimetry on the reference
print medium as described in Annex B. For the most part, the image colours will be within the reference colour gamut.
However, it is possible for some image colours to be slightly outside (this is somewhat dependent on how the convex hull
of the gamut is constructed). It is sometimes necessary to gamut map the results of colour rendering and re-rendering
processing to exactly fit the destination device colour gamut.
4 © ISO 2007 – All rights reserved

The description and typical usage of the natural images are given in Table 2. The descriptive names of these
images are given following the identification code. Figure 1 shows reduced size sRGB reproductions of the
natural images. Statistical and gamut data for each of the natural images are shown in Annex F, as
* * *
histograms of the L values and a versus b plots for each image, respectively.
Table 2 — Natural images
Aspect,
Name Description and typical usage
image size
N1 Bride and groom Horizontal, Image of a bride wearing white clothes and groom wearing black clothes.
2 560 × 2 048 Used to evaluate the rendering of human skin tones and neutral colours,
especially highlights and shadows.
pixels
N2 People Horizontal, Image consisting of five people wearing colourful clothes, sitting on a dark
leather couch. Used to evaluate the colour rendering of extremely colourful
2 560 × 2 048
pixels objects in the presence of skin tones and neutrals.
N3 Cashew nuts Vertical, Image of dried fruits and filled containers used to evaluate tonal and colour
2 048 × 2 560 rendering, in particular adjustments for grey component replacement.
pixels
N4 Meal Horizontal, Image with widely recognizable cooked food and pastel colours. Used to
2 560 × 2 048 evaluate high-key tonal rendering and food memory colours.
pixels
N5 Mandolin Vertical, Image of goods, including metallic objects, used to evaluate the
2 048 × 2 560 reproduction of colours, as well as the reproduction of the lustrous
appearances of metallic objects.
pixels
N6 Tailor scene Horizontal, Still-life image of textile used to evaluate the tone reproduction in a range
of neutrals and textile structures (object moiré).
2 560 × 2 048
pixels
N7 Wool Horizontal, Image of different coloured balls of wool used to evaluate the reproduction
of details in highly chromatic areas.
2 560 × 2 048
pixels
N8 Fruits Square, Image of a range of fruits and vegetables. The memory colours of
2 024 × 2 024 strawberries, oranges, lemons, green grapes, apples, pears, tomatoes and
bell peppers are particularly suitable for the evaluation of the naturalness of
pixels
colour re-rendering processes.

a)  N1 Bride and groom b)  N2 People

c)  N3 Cashew nuts d)  N4 Meal

e)  N5 Mandolin f)  N6 Tailor scene
Figure 1 (continued)
6 © ISO 2007 – All rights reserved

g)  N7 Wool h)  N8 Fruits
Figure 1 — Reduced size sRGB reproductions of the natural images
5.4 Synthetic images
5.4.1 Colour charts
There are eight colour charts, each of which consists of a number of colour patches that sample the reference
colour gamut. Each chart contains a number of patches at two hue angles, with each pair separated by 180°.
The design intent was to provide samples at hue angle intervals of 22,5° (from 0° to 337,5°). However, the
limitations imposed by 8-bit data means that the intended hue angles can only be approximated to within ±1°.
* *
The colour charts show all the samples within the reference colour gamut at L intervals of 10 (from L = 0 to
* * * *
* *
L = 100) and C intervals of 10 (from C = 0 to the C value above the maximum C value for that L
ab ab ab ab
*
value from the reference colour gamut). These maximum C values are given in Table 3, and are derived
ab
from the reference colour gamut described in Annex B of this part of ISO 12640, rounded to the nearest value.
Again, the limitations of the 8-bit data mean that the intended values shown in Table 3 can only be
* *
*
approximated. The L values achieved are to within ±0,2, and the C values to within ±1 C
ab ab
.
*
*
Because of this design, the maximum and minimum L values, and maximum C values, in the charts lie
ab
outside the reference colour gamut. This ensures that the whole of the reference colour gamut can be
evaluated (within the patch sampling limitations of the charts). The CIELAB values for each patch in the charts
are given in Annex G.
*
NOTE Applications that show the CIELAB values when these files are opened are likely to show the L values as the
integer value given in Table 3, despite the limited accuracy caused by the 8-bit resolution. Thus these are the values
quoted in Annex G.
The size of each chart is 275 mm × 137 mm. The size of each colour patch is 10 mm × 10 mm and the
*
distance between adjacent patches is 1 mm. Each chart has a grey background of L = 80.
Figure 2 shows reduced size reproductions of the eight colour charts.
*
*
Table 3 — Colour charts: Maximum chroma value ( C ) with respect to lightness (L )
ab
and hue angle (h )
ab
*
*
Maximum C for L =
ab
h
ab
10 20 30 40 50 60 70 80 90
0° 26 52 74 91 91 82 67 47 25
22,5° 23 50 73 94 95 86 71 51 28
45° 21 45 70 91 100 99 88 67 37
67,5° 16 35 53 70 85 97 104 105 69
90° 14 30 47 62 75 88 101 112 120
112,5° 14 31 47 64 77 90 100 105 96
135° 17 37 56 76 91 99 96 81 50
157,5° 20 43 67 90 99 93 80 60 34
180° 20 41 62 81 92 86 71 52 28
202,5° 20 38 55 69 81 77 66 49 27
225° 20 38 53 65 76 72 62 47 27
247,5° 24 42 58 69 72 64 53 39 21
270° 32 55 70 75 70 61 49 34 19
292,5° 55 85 90 85 76 64 50 35 18
315° 46 85 101 97 87 73 58 41 21
337,5° 31 63 85 102 99 88 70 49 26

8 © ISO 2007 – All rights reserved

Figure 2 — Reduced size sRGB reproductions of the colour charts CC1 to CC8
5.4.2 Vignettes
The vignettes were built as two sets, a full and a reduced colour gamut set. All vignettes are defined for eight
hue angles, at 45° intervals between 0° and 315°, inclusive. For the full reference colour gamut set, the first
*
*
vignette at each hue angle is linearly scaled from black (L = 3,137 3, C = 0) to the maximum chroma of the
ab
reference colour gamut at the corresponding level of lightness as shown in Table 4. The second vignette for
* *
* *
each hue angle has the constant L value given in Table 4 from grey ( C = 0) to the L and maximum C
ab ab
*
* *
values given in Table 4. The third vignette is scaled from white (L = 100, C = 0) to the L and maximum
ab
*
C values given in Table 4.
ab
The reduced reference colour gamut set consists of the same arrangement, except that the minimum and
* *
maximum lightness is restricted to L = 10 and L = 90, respectively, and the chroma values to 85 % of the
*
reference colour gamut for the same levels of lightness L as shown in Table 4.
*
NOTE The 8-bit resolution necessitates some of the C values being rounded.
ab
The size of the vignettes is 250 mm in length and 10 mm in width. The vignettes are calculated in 4 096 steps.
*
They are arranged to a set on a grey background with L = 80. The size of one set is 308 mm × 263 mm.
Figure 3 shows a reduced size reproduction of the vignette CV1.
Table 4 — Maximum and reduced chroma values and corresponding level of lightness
for 8 hue angles
Hue angle
h
ab
Parameter
0° 45° 90° 135° 180° 225° 270° 315°
*
Lightness (L) 48 52 95 65 50 51 37 31
*
Maximum chroma ( C) 92 101 123 100 92 75 76 100
ab
* *
Colour values (a , b ) (92, 0) (71, 71) (0, 123) (−71, 71) (−92, 0) (−53, −53) (0, −76) (71, −71)
*
Reduced chroma ( C) 78 86 105 85 78 64 65 85
ab
* *
Colour values (a , b ) (78, 0) (61, 61) (0, 105) (−60, 60) (−78, 0) (−45, −45) (0, −65) (60, −60)

Figure 3 — Reduced size sRGB reproduction of the maximum chroma vignette CV1
5.4.3 Synthetic image format
The colour charts and vignettes are written in the PDF 1.4 format.
10 © ISO 2007 – All rights reserved

6 Electronic data
6.1 Image file characteristics
Image data are contained in 18 data files that are included in this part of ISO 12640. File names correspond to
the image IDs as described in 5.3 and 5.4. Table 5 shows the file name, size, colour values and descriptive
name of each data file, as well as the pixel height and width of each image. The file size shown represents the
file as recorded and includes headers, etc. Image height and width are provided for raster files. The check-
sums given in Annex C may be used to check the data integrity.
The restrictions on the use of these image data files is described in Annex A.
Table 5 — Image file characteristics
File size Height Width Colour values
File name Descriptive name
* * *
bytes pixels pixels L , a , b
N1.TIF 31 458 304 2 048 2 560 Three 16-bit values Bride and groom
N2.TIF 31 458 304 2 048 2 560 Three 16-bit values People
N3.TIF 31 458 304 2 560 2 048 Three 16-bit values Cashew nuts
N4.TIF 31 458 304 2 048 2 560 Three 16-bit values Meal
N5.TIF 31 458 304 2 560 2 048 Three 16-bit values Mandolin
N6.TIF 31 458 304 2 048 2 560 Three 16-bit values Tailor scene
N7.TIF 31 458 304 2 048 2 560 Three 16-bit values Wool
N8.TIF 24 580 480 2 024 2 024 Three 16-bit values Fruits
CC1.PDF 12 507 — — Three 8-bit values Chart h 0°/180°
ab
CC2.PDF 14 001 — — Three 8-bit values Chart h 22,5°/202,5°
ab
CC3.PDF 13 869 — — Three 8-bit values Chart h 45°/225°
ab
CC4.PDF 13 982 — — Three 8-bit values Chart h 67,5°/247,5°
ab
CC5.PDF 12 377 — — Three 8-bit values Chart h 90°/270°
ab
CC6.PDF 14 115 — — Three 8-bit values Chart h 112,5°/292,5°
ab
CC7.PDF 14 057 — — Three 8-bit values Chart h 135°/315°
ab
CC8.PDF 14 186 — — Three 8-bit values Chart h 157,5°/337,5°
ab
CV1.PDF 90 015 — — Three 8-bit values Vignette maximal chroma
CV2.PDF 89 213 — — Three 8-bit values Vignette reduced chroma

6.2 Image file formats
The natural images N1.TIF to N8.TIF are recorded as 16-bit CIELAB data in accordance with ISO 12639 (also
readable by TIFF 6.0 extended, photometric interpretation tag 8, CIELAB, signed encoding). The colour charts
and vignettes CC1.PDF to CC8.PDF and CV1.PDF and CV2.PDF are recorded as PDF files based on
PDF 1.4.
Annex D shows the file header of image N1.TIF.

Annex A
(normative)
Guidance for use of digital data
A.1 General
To ensure that these images can be used successfully for the testing and comparisons for which they are
intended, all use shall conform to the procedures and guidelines described in A.2 and A.3.
A.2 Guidelines for use
A.2.1 Reproduction
All reproductions of these images shall contain an annotation identifying this part of ISO 12640 as the data
source and shall retain the colour space identifier included in the image data.
A.2.2 Modification
Any images created by modification of these data (derivative images) shall also have a visible identifier added
within the image. The accompanying material shall include a tabulation of the steps used to modify the image
data including all editing steps used as well as any data rescaling or interpolation.
A.2.3 Colour manipulation
Any colour or tonal manipulation of these images shall be restricted to “global” changes only.
A.2.4 Cropping
Cropping of these images shall be permitted so long as the appropriate image colour space identifier is
included as part of, or with, the images.
A.3 Guidelines for distribution and sharing
A.3.1 General
Many of the intended uses of these images require that they be used at several locations and/or by several
participants in test programs. The following uses have been interpreted to be acceptable and allowable by ISO.
A.3.2 For-profit sale
Neither the data, nor images printed from these data, shall be sold “for-profit” except as defined in A.3.3.
A.3.3 Test and evaluation packages
It shall be permitted to include the data corresponding to these images, or derivations of these images, as part
of test and evaluation packages to be sold or provided free of charge where an authentic copy of this part of
ISO 12640 is included as part of the complete package.
12 © ISO 2007 – All rights reserved

NOTE It is recognized that certain test and evaluation packages that will make use of these images might need to
embed the data to be used within other data processing procedures. The inclusion of an authentic copy of this part of
ISO 12640, obtained from the appropriate standards agency, as part of the package will allow the inclusion of similar or
derived data as needed within the package.
A.3.4 Test and evaluation programs
Copies of these data files, or derivative files, may be exchanged between participants in test and evaluation
programs. The sponsoring organization shall be capable of showing ownership of an authentic copy of this
part of ISO 12640.
A.3.5 Reports
It shall be permitted to display these images as part of the report of test programs, or in advertisements, as
long as the organization sponsoring the display is in possession of an authentic copy of this part of ISO 12640.

Annex B
(informative)
Definition of the reference colour gamut
B.1 Development of the reference colour gamut
The reference colour gamut defined for this part of ISO 12640 was derived from three different colour gamuts
developed quite independently, but for similar reasons. The first was developed within ISO/TC 130 in order to
provide an estimate of the gamut of surface colours for the purposes of this part of ISO 12640. The second
was produced by Hewlett-Packard as the gamut of colours produced by all colour printers, during their own
product development work, and offered to the International Color Consortium (ICC) as a reference colour
gamut for the Profile Connection Space for perceptual renderings defined in ICC.1:2004-04. It was also
offered to ISO/TC 130 for consideration in the definition of the reference gamut required for this part of
ISO 12640. During the development of this standard another useful gamut was brought to the attention of the
committee. This is a gamut known as PhotoGamutRGB, which is based on measurement of the results
obtained from silver halide printers used for producing photographic prints from digital photographs.
On review it became clear that, although there were some differences, there was also considerable similarity
between these gamuts. So, it was agreed by the committee that the data from the three sources could be
reconciled in order to produce the single reference colour gamut defined for this part of ISO 12640. This
reconciliation is described in B.5. However, for information purposes, the derivation of each of the gamuts is
briefly described.
B.2 Gamut of surface colours
The initial specification for the reference colour gamut for this part of ISO 12640 was obtained by finding the
maximum gamut obtainable with surface colours, according to the published data available to the committee
[7] [5]
in 1998. The main sources of this data were the Pointer gamut, data for Pantone colours, the SOCS data
and data for photographic media available to the committee. Some additional samples were also measured.
[7]
In 1980, Pointer published an investigation of the gamut of real surface colours , in which colour data was
analysed from the following sources:
⎯ 768 colours from the Munsell Limit Color Cascade;
⎯ 310 colours from the Matte Munsell Atlas;
⎯ 1 393 colours from ink and paint samples, textiles, coloured plastics and papers (measured in the
[7]
investigation );
⎯ 1 618 colours describing flower colours (tabulated by the Royal Horticultural Society).
Altogether, the colour coordinates of 4 089 colours were available.
[7]
Pointer combined these colour data and published the maximum chroma value at 36 hue angles and
16 lightness levels. However, the Pointer gamut data refer to CIE standard illuminant C, whereas the
committee needed the gamut with respect to illuminant D50. The Pointer gamut boundary data was therefore
converted to that for D50 using the Bradford chromatic adaptation conversion used in CIECAM97s. The D50
Pointer data were then combined with other colour data exhibiting high chroma values. In particular, the data
for 1 025 Pantone colours, a series of new colour data measured from printed samples and the colorimetric
[5]
data from the SOCS data set (ISO/TR 16066 ) were included.
14 © ISO 2007 – All rights reserved

From these XYZ data the colour gamut was calculated as a convex hull and then transformed into the CIELAB
colour space. Table B.1 shows the maximum chroma value obtainable with surface colours for 36 hue angles
and 19 lightness levels calculat
...

INTERNATIONAL ISO
STANDARD 12640-3
First edition
2007-07-15
Graphic technology — Prepress digital
data exchange —
Part 3:
CIELAB standard colour image data
(CIELAB/SCID)
Technologie graphique — Échange de données numériques de
préimpression —
Partie 3: Données d'images en couleur normalisées CIELAB
(CIELAB/SCID)
Reference number
©
ISO 2007
PDF disclaimer
PDF files may contain embedded typefaces. In accordance with Adobe's licensing policy, such files may be printed or viewed but shall
not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading a PDF file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create the PDF file(s) constituting this document can be found in the General Info relative to
the file(s); the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the files are suitable for
use by ISO member bodies. In the unlikely event that a problem relating to them is found, please inform the Central Secretariat at the
address given below.
This CD-ROM contains:
1) the publication ISO 12640-3:2007 in portable document format (PDF), which can be viewed using
Adobe® Acrobat® Reader;
2) image files N1_16_LAB.tif, N2_16_LAB.tif, N3_16_LAB.tif, N4_16_LAB.tif, N5_16_LAB.tif,
N6_16_LAB.tif, N7_16_LAB.tif and N8_16_LAB.tif correspond to the natural images shown in
Figure 1;
3) image files CC1.pdf, CC2.pdf, CC3.pdf, CC4.pdf, CC5.pdf, CC6pdf, CC7.pdf and CC8.pdf
correspond to the colour charts shown in Figure 2;
4) image files CV1.pdf and CV2.pdf correspond to the vignettes shown in Figure 3.
Adobe and Acrobat are trademarks of Adobe Systems Incorporated.

©  ISO 2007
All rights reserved. The appropriate use, transmittal, and reproduction of the content of this CD-ROM are specified in Annex A of
ISO 12640-3:2
...

INTERNATIONAL ISO
STANDARD 12640-3
First edition
2007-07-15
Graphic technology — Prepress digital
data exchange —
Part 3:
CIELAB standard colour image data
(CIELAB/SCID)
Technologie graphique — Échange de données numériques de
préimpression —
Partie 3: Données d'images en couleur normalisées CIELAB
(CIELAB/SCID)
Reference number
©
ISO 2007
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2007
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 [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2007 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Requirements . 2
5 Data description and definition. 3
5.1 Data set definition. 3
5.2 Colour encoding used in this part of ISO 12640. 3
5.3 Natural images . 4
5.4 Synthetic images . 7
6 Electronic data . 11
6.1 Image file characteristics. 11
6.2 Image file formats . 11
Annex A (normative) Guidance for use of digital data. 12
Annex B (informative) Definition of the reference colour gamut . 14
Annex C (normative) Check-sum data . 21
Annex D (informative) Typical TIFF file headers used for image data. 22
Annex E (informative) Text insertion. 24
Annex F (informative) Histogram and gamut plots. 25
Annex G (informative) CIELAB values in colour charts . 29
Bibliography . 33

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 12640-3 was prepared by Technical Committee ISO/TC 130, Graphic technology.
ISO 12640 consists of the following parts, under the general title Graphic technology — Prepress digital data
exchange:
⎯ Part 1: CMYK standard colour image data (CMYK/SCID)
⎯ Part 2: XYZ/sRGB encoded standard colour image data (XYZ/SCID)
⎯ Part 3: CIELAB standard colour image data (CIELAB/SCID)
The following parts are under preparation:
⎯ Part 4: Wide gamut display-referred standard colour image data (TBDencoded/SCID)
⎯ Part 5: Scene-referred standard colour image data (RIMM/SCID)

iv © ISO 2007 – All rights reserved

Introduction
0.1 Need for standard digital test images
Standard test images provide a set of data that can be used for any of the following tasks:
⎯ evaluating the colour reproduction of imaging systems;
⎯ evaluating colour image output devices;
⎯ evaluating the effect of image processing algorithms applied to the images;
⎯ evaluating the coding technologies necessary for the storage and transmission of high-definition image
data.
Because they exist as standard, well-defined, high-quality image data sets, typical of the range of image
content commonly encountered, they enable users to be confident that the images will produce good quality
reproductions, if properly rendered, and that they provide a reasonable test of the evaluation task being
undertaken. No limited set of images can fully test any system, but the sets provided give as reasonable a test
as can be expected from a limited image set. Furthermore, the existence of a standard image data set
enables users in different locations to produce comparisons without the need to exchange images prior to
reproduction.
However, different applications require that the standard image data be provided in different image states
using different image encodings (see ISO 22028-1). The user needs to select those appropriate to the
evaluation task being undertaken. Whilst transformation of the image data to another image state is always
possible, there is, in general, no agreement amongst experts as to how this is best done. Thus, it has been
considered preferable to provide data in three different image states in the various parts of ISO 12640.
Part 1 of ISO 12640 provides a set of 8-bits-per-channel data that is defined in terms of CMYK dot
percentages. The colours resulting from reproduction of CMYK data are strictly defined only at the time of
printing and, as such, the data are only applicable to evaluation of CMYK printing applications.
Transformations to other image states and colour encodings are not necessarily well defined. In fact, the data
might not even be useful for CMYK printing processes different from those typically found in traditional graphic
arts applications as the image data are defined to produce “pleasing” images when reproduced on systems
using “typical” inks and producing “typical” tone value rendering. Printing systems that use inks of a distinctly
different colour, or produce a very different tone value rendering, will not reproduce them as pleasing images
without a well-defined colour transformation. Moreover, with a bit depth of only 8 bits per channel, any colour
transformation employed will probably introduce artefacts.
Part 2 of ISO 12640 provides a set of test image data encoded both as XYZ tristimulus values with a depth of
16 bits per channel and as sRGB (defined in IEC 61966-2-1) with a bit depth of 8 bits per channel. (The higher
bit depth for the XYZ encoding is necessary because of the perceptual non-uniformity of the XYZ colour
space.) Both sets of data are optimized for viewing on a reference sRGB CRT display in the reference sRGB
viewing environment, and relative to CIE standard illuminant D65 for which the XYZ values were computed.
The images are mainly designed to be used on systems utilizing sRGB as the reference encoding, and as
such are mainly applicable to the consumer market and those systems for which the colour monitor is the
“hub” device. Although such systems are used for some applications in the graphic arts industry, sRGB is by
no means the most common image encoding. Furthermore, a particular drawback is the fact that the sRGB
colour gamut is quite different in shape than the colour gamut of typical offset printing. This difference can
necessitate fairly aggressive colour re-rendering to produce optimal prints from sRGB image data.
In order to be useful for applications where large, print-referred output gamuts are encountered, common in
graphic technology and photography, it was felt that it would be desirable to produce an image set in which
some colours are permitted to be encoded close to the boundary of the full colour gamut attainable with
surface colours. Furthermore, from the perspective of colour management it is advantageous if the images are
referenced to illuminant D50, which is the predominant reference illuminant used in graphic arts and
photography, both for viewing and measurement. For this reason it has also become the predominant
reference illuminant for most colour management applications.
The purpose of this part of ISO 12640 is, therefore, to provide a test image data set with a large colour gamut
related to illuminant D50. The bit depth of the natural images is 16 bits per channel, while the colour charts
and vignettes are 8 bits per channel.
0.2 Definition of the reference colour gamut
The reference colour gamut defined for this part of ISO 12640 originated from three quite separate sources.
However, it was noted that there was considerable similarity between the three. One definition came from
work within ISO/TC 130 itself, and this arose by consideration of various sets of published data, which
together were taken to define the colour gamut of surface colours. The other definitions arose from work within
Hewlett-Packard, which was focused on the colour gamuts obtainable by printing, and that of a group of
German photographic printing experts. The similarity of these led to the conclusion that it would be desirable
to reconcile them into a single gamut that would be taken as the reference colour gamut for this part of
ISO 12640. Full details of the reference colour gamut and its derivation are given in Annex B.
0.3 Characteristics of the test images
The performance of any colour reproduction system is normally evaluated both subjectively (by viewing the
final output image) and objectively (by measurement of control elements). This requirement dictated that the
test images include both natural scenes (pictures) and synthetic images (colour charts and colour vignettes).
Because the results of subjective image evaluation are strongly affected by the image content, it was
important to ensure that the natural images were of high quality and contained diverse subject matter.
However, by requiring images to look natural, it is difficult within a single, relatively small sample set to
produce elements in the scene that contain the subtle colour differences required in such test images and that
cover the full reference colour gamut defined. It is also important to have some images that contain subtle
differences in near-neutral colours. Thus, while most images contain colours that extend to the gamut
boundary, this is often only for a limited range of hues in each image. The full reference colour gamut can only
be explored by utilizing the synthetic colour chart.
A survey was conducted of all ISO/TC 130 member countries to identify desirable image content and to solicit
submission of suitable images for consideration. The image set that resulted consists of eight natural images,
eight colour charts and two colour vignettes. The natural images include flesh tones, images with detail in the
extreme highlights or shadows, neutral colours, brown and wood-tone colours that are often difficult to
reproduce, memory colours, complicated geometric shapes, fine detail, and highlight and shadow vignettes.
The colour charts and colour vignettes show the reference colour gamut (in CIE Lab colour space) in
cross-sections for 16 and 8 hue angles, respectively.
0.4 File format of the digital test images
* * *
All of the images consist of pixel interleaved data (L then a then b ) with the data origin at the upper left of the
image, as viewed naturally, and organized by rows. These data are available as individual files, which are a
normative part of this part of this part of ISO 12640. The image file format is as specified in ISO 12639:2004,
Annex H, with BitsPerSample set to 16, 16, 16. The images can be imported and manipulated as necessary
by a wide variety of imaging software tools and platforms commonly in general use in the industry. (See
Annex D for details of the TIFF header.)
All colour charts and vignettes consist of files in Adobe® PDF format.

vi © ISO 2007 – All rights reserved

INTERNATIONAL STANDARD ISO 12640-3:2007(E)

Graphic technology — Prepress digital data exchange —
Part 3:
CIELAB standard colour image data (CIELAB/SCID)
1 Scope
This part of ISO 12640 specifies a set of standard large gamut colour images (encoded as 16-bit CIELAB
digital data) that can be used for the evaluation of changes in image quality during coding, image processing
(including transformation, compression and decompression), displaying on a colour monitor and printing.
These images can be used for research, testing and assessing of output systems such as printers, colour
management systems and colour profiles.
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 3664, Viewing conditions — Graphic technology and photography
ISO 12639:2004, Graphic technology — Prepress digital data exchange — Tag image file format for image
technology (TIFF/IT)
ISO 13655, Graphic technology — Spectral measurement and colorimetric computation for graphic arts
images
ISO 22028-1, Photography and graphic technology — Extended colour encodings for digital image storage,
manipulation and interchange — Part 1: Architecture and requirements
CIE Publication 15:2004, Colorimetry
ICC.1:2004-04, Image technology colour management — Architecture, profile format, and data structure
TIFF, Revision 6.0 Final, Aldus Corporation (now Adobe Systems Incorporated), June 3, 1992
PDF Reference: Adobe Portable Document Format, Version 1.4 3rd edn., Adobe Systems Incorporated,
(ISBN 0-201-75839-3)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
check sum
sum of the digits in a file that can be used to check if a file has been transferred properly
NOTE Often, only the least significant bits are summed.
3.2
colour gamut
solid in a colour space, consisting of all those colours that are present in a specific scene, artwork, photograph,
photomechanical or other reproduction; or are capable of being created using a particular output device and/or
medium
[ISO 12231]
3.3
colour sequence
order in which the colours are stored in a data file
3.4
colour space
geometric representation of colours in space, usually of three dimensions
[CIE Publication 17-1987 (845-03-25)]
3.5
colour value
numeric values associated with each of the pixels
3.6
data range
range of integers for a given variable in between a minimal and maximal value
3.7
global colour change
change to the colours in an image (often selectively by colour region) applied consistently to all parts of the
image
NOTE This is in contrast to a local colour change where selected spatial areas of an image are changed separately
from the rest of the image area.
3.8
orientation
specifies the origin and direction of the first line of data with respect to the image content as viewed by the end
user
NOTE The codes used to specify orientation are contained in ISO 12639:2004.
3.9
pixel
smallest discrete picture element in a digital image file
3.10
pixel interleaving
* * *
colour data organized such that the L , a and b colour space values for one pixel are followed by the same
sequence of colour values for the next pixel; the specific order of colour components is determined by the
ColorSequence tag as defined in ISO 12639
NOTE Other forms of colour data interleaving are line and plane.
4 Requirements
This part of ISO 12640 consists of the images contained in the 18 image data files which are part of this part
of ISO 12640. Their file names are listed in Table 4. The image characteristics of these data are described in
Clause 5 and the electronic data structure in Clause 6.
2 © ISO 2007 – All rights reserved

5 Data description and definition
5.1 Data set definition
The set of standard colour image data consists of eight natural (photographed) images and ten synthetic
images created digitally on a computer. The synthetic images consist of eight colour charts consisting of
various patches, each 10 mm square, and two colour vignettes. The natural images are identified as N1 to N8,
and each of them also has a descriptive name derived from the picture content (e.g. bride and groom). The
synthetic images are identified as CC1 to CC8, CV1 and CV2.
The images are identified by the designation CIELAB/SCID. The co-ordinates of the text insertion are provided
in Annex E.
NOTE The image set defined in this part of ISO 12640 is based on the large gamut defined in Annex B. Image sets
contained in other parts of ISO 12640 are based on different gamuts and can be more suitable for use in evaluation of
other applications.
5.2 Colour encoding used in this part of ISO 12640
5.2.1 Image data encoding
The image data encoding is defined in accordance with ISO 22028-1 requirements as follows.
The image data are the desired CIELAB colorimetry as defined by CIE Publication 15, and measured in
accordance with ISO 13655, of reproductions of the images on the reference medium, with the reference
medium white point selected as the colour space white point. The image data are output-referred, having been
rendered to the reference medium of the ICC.1:2004-04 perceptual rendering intent, which is defined as a
hypothetical print on a substrate specified to have a neutral reflectance of 89 % (the reference medium white
point) and the darkest printable colour on this medium is assumed to have a neutral reflectance of 0,347 31 %
of the substrate reflectance (the reference medium black point). The rendering target colour gamut for the
reference medium is specified in Annex B. The reference viewing environment is based on standard viewing
condition P2, as specified for graphic arts and photography in ISO 3664, but extended in the following way:
the surfaces immediately surrounding the image are assumed to be a uniform matt grey with a reflectance of
20 %. The reference viewing environment is also assumed to have a viewing flare of 0,75 % of the luminance
of the reference white. The CIELAB image data are encoded as specified in 5.2.3 and 5.2.4.
5.2.2 Image data arrangement
* * *
The image data are pixel-interleaved in the colour sequence of L then a then b (16 bits) for the natural
* * *
images and L then a then b (8 bits) for the colour charts and the vignettes. The arrangement of data follows
the scanning of each image from the upper left corner to the upper right, then moving to the next lower
horizontal line. The resolution is 12 pixels/mm for every natural image.
5.2.3 CIELAB image data (16 bits per channel)
The CIELAB data for the natural images are encoded as 16-bit integers per channel, derived by multiplying
* * *
the L , a and b values for each pixel with the corresponding value for the data range.
*
⎛⎞
L
*
L=×round⎜⎟65 535
16bit
⎜⎟
⎝⎠
**
aa=×round (256 ) (1)
16bit
**
bb=×round (256 )
16bit
* * * * * *
where L , a and b represent normalised 16-bit values of L , a and b .
16bit 16bit 16bit
The data range of the values is:
* * *
L ∈{0.100}, a ∈{−128.+127} and b ∈{−128.+127},
* * * * *
L ∈{0.65 535}, a ∈{−32 768.+32 512} and b ∈{−32 768.+32 512}, a and b are signed
16bit 16bit 16bit 16bit 16bit
integers.
NOTE −32 678 = −128 × 256, and 32 512 = 127 × 256.
5.2.4 CIELAB image data (8 bits per channel)
*
The CIELAB data for the colour charts are encoded as 8-bit integers per channel, derived by multiplying the L ,
* *
a and b values for each pixel with the corresponding value for the data range.
*
⎛⎞
L
*
L=×round⎜⎟255
8bit
⎜⎟
⎝⎠
**
aa= round ( ) (2)
8bit
**
bb= round ( )
8bit
* * * * * *
where L , a and b represent normalised 8 bit values of L , a and b .
8bit 8bit 8bit
The data range of the values is:
* * *
L ∈{0.100}, a ∈{−128.+127} and b ∈{−128.+127},
* * * * *
L ∈{0.255}, a ∈{−128.+127} and b ∈{−128.+127}, the a and b are signed integers.
8bit 8bit 8bit 8bit 8bit
5.3 Natural images
The characteristics of the eight natural images, shown in Figure 1, are given in Table 1.
Table 1 — Characteristics for natural images
Parameter Characteristics
Resolution 12 pixels/mm
* * *
16 bits/channel L , a and b , with respect to illuminant D50 (defined as
* * *
Colour values media-relative, i.e. such that a white in the image has the L , a and b values
of 100, 0, 0)
ISO 12639:2004, Annex H, with BitsPerSample set to 16, 16, 16
File format
This format also readable with TIFF 6.0 with extension, photometric
interpretation tag 8, CIELAB, signed encoding.
Label on image CIELAB/SCID
Image data orientation Horizontal scanning starting from top left and ending at bottom right

NOTE The natural images have been colour-rendered to produce the desired image colorimetry on the reference
print medium as described in Annex B. For the most part, the image colours will be within the reference colour gamut.
However, it is possible for some image colours to be slightly outside (this is somewhat dependent on how the convex hull
of the gamut is constructed). It is sometimes necessary to gamut map the results of colour rendering and re-rendering
processing to exactly fit the destination device colour gamut.
4 © ISO 2007 – All rights reserved

The description and typical usage of the natural images are given in Table 2. The descriptive names of these
images are given following the identification code. Figure 1 shows reduced size sRGB reproductions of the
natural images. Statistical and gamut data for each of the natural images are shown in Annex F, as
* * *
histograms of the L values and a versus b plots for each image, respectively.
Table 2 — Natural images
Aspect,
Name Description and typical usage
image size
N1 Bride and groom Horizontal, Image of a bride wearing white clothes and groom wearing black clothes.
2 560 × 2 048 Used to evaluate the rendering of human skin tones and neutral colours,
especially highlights and shadows.
pixels
N2 People Horizontal, Image consisting of five people wearing colourful clothes, sitting on a dark
leather couch. Used to evaluate the colour rendering of extremely colourful
2 560 × 2 048
pixels objects in the presence of skin tones and neutrals.
N3 Cashew nuts Vertical, Image of dried fruits and filled containers used to evaluate tonal and colour
2 048 × 2 560 rendering, in particular adjustments for grey component replacement.
pixels
N4 Meal Horizontal, Image with widely recognizable cooked food and pastel colours. Used to
2 560 × 2 048 evaluate high-key tonal rendering and food memory colours.
pixels
N5 Mandolin Vertical, Image of goods, including metallic objects, used to evaluate the
2 048 × 2 560 reproduction of colours, as well as the reproduction of the lustrous
appearances of metallic objects.
pixels
N6 Tailor scene Horizontal, Still-life image of textile used to evaluate the tone reproduction in a range
of neutrals and textile structures (object moiré).
2 560 × 2 048
pixels
N7 Wool Horizontal, Image of different coloured balls of wool used to evaluate the reproduction
of details in highly chromatic areas.
2 560 × 2 048
pixels
N8 Fruits Square, Image of a range of fruits and vegetables. The memory colours of
2 024 × 2 024 strawberries, oranges, lemons, green grapes, apples, pears, tomatoes and
bell peppers are particularly suitable for the evaluation of the naturalness of
pixels
colour re-rendering processes.

a)  N1 Bride and groom b)  N2 People

c)  N3 Cashew nuts d)  N4 Meal

e)  N5 Mandolin f)  N6 Tailor scene
Figure 1 (continued)
6 © ISO 2007 – All rights reserved

g)  N7 Wool h)  N8 Fruits
Figure 1 — Reduced size sRGB reproductions of the natural images
5.4 Synthetic images
5.4.1 Colour charts
There are eight colour charts, each of which consists of a number of colour patches that sample the reference
colour gamut. Each chart contains a number of patches at two hue angles, with each pair separated by 180°.
The design intent was to provide samples at hue angle intervals of 22,5° (from 0° to 337,5°). However, the
limitations imposed by 8-bit data means that the intended hue angles can only be approximated to within ±1°.
* *
The colour charts show all the samples within the reference colour gamut at L intervals of 10 (from L = 0 to
* * * *
* *
L = 100) and C intervals of 10 (from C = 0 to the C value above the maximum C value for that L
ab ab ab ab
*
value from the reference colour gamut). These maximum C values are given in Table 3, and are derived
ab
from the reference colour gamut described in Annex B of this part of ISO 12640, rounded to the nearest value.
Again, the limitations of the 8-bit data mean that the intended values shown in Table 3 can only be
* *
*
approximated. The L values achieved are to within ±0,2, and the C values to within ±1 C
ab ab
.
*
*
Because of this design, the maximum and minimum L values, and maximum C values, in the charts lie
ab
outside the reference colour gamut. This ensures that the whole of the reference colour gamut can be
evaluated (within the patch sampling limitations of the charts). The CIELAB values for each patch in the charts
are given in Annex G.
*
NOTE Applications that show the CIELAB values when these files are opened are likely to show the L values as the
integer value given in Table 3, despite the limited accuracy caused by the 8-bit resolution. Thus these are the values
quoted in Annex G.
The size of each chart is 275 mm × 137 mm. The size of each colour patch is 10 mm × 10 mm and the
*
distance between adjacent patches is 1 mm. Each chart has a grey background of L = 80.
Figure 2 shows reduced size reproductions of the eight colour charts.
*
*
Table 3 — Colour charts: Maximum chroma value ( C ) with respect to lightness (L )
ab
and hue angle (h )
ab
*
*
Maximum C for L =
ab
h
ab
10 20 30 40 50 60 70 80 90
0° 26 52 74 91 91 82 67 47 25
22,5° 23 50 73 94 95 86 71 51 28
45° 21 45 70 91 100 99 88 67 37
67,5° 16 35 53 70 85 97 104 105 69
90° 14 30 47 62 75 88 101 112 120
112,5° 14 31 47 64 77 90 100 105 96
135° 17 37 56 76 91 99 96 81 50
157,5° 20 43 67 90 99 93 80 60 34
180° 20 41 62 81 92 86 71 52 28
202,5° 20 38 55 69 81 77 66 49 27
225° 20 38 53 65 76 72 62 47 27
247,5° 24 42 58 69 72 64 53 39 21
270° 32 55 70 75 70 61 49 34 19
292,5° 55 85 90 85 76 64 50 35 18
315° 46 85 101 97 87 73 58 41 21
337,5° 31 63 85 102 99 88 70 49 26

8 © ISO 2007 – All rights reserved

Figure 2 — Reduced size sRGB reproductions of the colour charts CC1 to CC8
5.4.2 Vignettes
The vignettes were built as two sets, a full and a reduced colour gamut set. All vignettes are defined for eight
hue angles, at 45° intervals between 0° and 315°, inclusive. For the full reference colour gamut set, the first
*
*
vignette at each hue angle is linearly scaled from black (L = 3,137 3, C = 0) to the maximum chroma of the
ab
reference colour gamut at the corresponding level of lightness as shown in Table 4. The second vignette for
* *
* *
each hue angle has the constant L value given in Table 4 from grey ( C = 0) to the L and maximum C
ab ab
*
* *
values given in Table 4. The third vignette is scaled from white (L = 100, C = 0) to the L and maximum
ab
*
C values given in Table 4.
ab
The reduced reference colour gamut set consists of the same arrangement, except that the minimum and
* *
maximum lightness is restricted to L = 10 and L = 90, respectively, and the chroma values to 85 % of the
*
reference colour gamut for the same levels of lightness L as shown in Table 4.
*
NOTE The 8-bit resolution necessitates some of the C values being rounded.
ab
The size of the vignettes is 250 mm in length and 10 mm in width. The vignettes are calculated in 4 096 steps.
*
They are arranged to a set on a grey background with L = 80. The size of one set is 308 mm × 263 mm.
Figure 3 shows a reduced size reproduction of the vignette CV1.
Table 4 — Maximum and reduced chroma values and corresponding level of lightness
for 8 hue angles
Hue angle
h
ab
Parameter
0° 45° 90° 135° 180° 225° 270° 315°
*
Lightness (L) 48 52 95 65 50 51 37 31
*
Maximum chroma ( C) 92 101 123 100 92 75 76 100
ab
* *
Colour values (a , b ) (92, 0) (71, 71) (0, 123) (−71, 71) (−92, 0) (−53, −53) (0, −76) (71, −71)
*
Reduced chroma ( C) 78 86 105 85 78 64 65 85
ab
* *
Colour values (a , b ) (78, 0) (61, 61) (0, 105) (−60, 60) (−78, 0) (−45, −45) (0, −65) (60, −60)

Figure 3 — Reduced size sRGB reproduction of the maximum chroma vignette CV1
5.4.3 Synthetic image format
The colour charts and vignettes are written in the PDF 1.4 format.
10 © ISO 2007 – All rights reserved

6 Electronic data
6.1 Image file characteristics
Image data are contained in 18 data files that are included in this part of ISO 12640. File names correspond to
the image IDs as described in 5.3 and 5.4. Table 5 shows the file name, size, colour values and descriptive
name of each data file, as well as the pixel height and width of each image. The file size shown represents the
file as recorded and includes headers, etc. Image height and width are provided for raster files. The check-
sums given in Annex C may be used to check the data integrity.
The restrictions on the use of these image data files is described in Annex A.
Table 5 — Image file characteristics
File size Height Width Colour values
File name Descriptive name
* * *
bytes pixels pixels L , a , b
N1.TIF 31 458 304 2 048 2 560 Three 16-bit values Bride and groom
N2.TIF 31 458 304 2 048 2 560 Three 16-bit values People
N3.TIF 31 458 304 2 560 2 048 Three 16-bit values Cashew nuts
N4.TIF 31 458 304 2 048 2 560 Three 16-bit values Meal
N5.TIF 31 458 304 2 560 2 048 Three 16-bit values Mandolin
N6.TIF 31 458 304 2 048 2 560 Three 16-bit values Tailor scene
N7.TIF 31 458 304 2 048 2 560 Three 16-bit values Wool
N8.TIF 24 580 480 2 024 2 024 Three 16-bit values Fruits
CC1.PDF 12 507 — — Three 8-bit values Chart h 0°/180°
ab
CC2.PDF 14 001 — — Three 8-bit values Chart h 22,5°/202,5°
ab
CC3.PDF 13 869 — — Three 8-bit values Chart h 45°/225°
ab
CC4.PDF 13 982 — — Three 8-bit values Chart h 67,5°/247,5°
ab
CC5.PDF 12 377 — — Three 8-bit values Chart h 90°/270°
ab
CC6.PDF 14 115 — — Three 8-bit values Chart h 112,5°/292,5°
ab
CC7.PDF 14 057 — — Three 8-bit values Chart h 135°/315°
ab
CC8.PDF 14 186 — — Three 8-bit values Chart h 157,5°/337,5°
ab
CV1.PDF 90 015 — — Three 8-bit values Vignette maximal chroma
CV2.PDF 89 213 — — Three 8-bit values Vignette reduced chroma

6.2 Image file formats
The natural images N1.TIF to N8.TIF are recorded as 16-bit CIELAB data in accordance with ISO 12639 (also
readable by TIFF 6.0 extended, photometric interpretation tag 8, CIELAB, signed encoding). The colour charts
and vignettes CC1.PDF to CC8.PDF and CV1.PDF and CV2.PDF are recorded as PDF files based on
PDF 1.4.
Annex D shows the file header of image N1.TIF.

Annex A
(normative)
Guidance for use of digital data
A.1 General
To ensure that these images can be used successfully for the testing and comparisons for which they are
intended, all use shall conform to the procedures and guidelines described in A.2 and A.3.
A.2 Guidelines for use
A.2.1 Reproduction
All reproductions of these images shall contain an annotation identifying this part of ISO 12640 as the data
source and shall retain the colour space identifier included in the image data.
A.2.2 Modification
Any images created by modification of these data (derivative images) shall also have a visible identifier added
within the image. The accompanying material shall include a tabulation of the steps used to modify the image
data including all editing steps used as well as any data rescaling or interpolation.
A.2.3 Colour manipulation
Any colour or tonal manipulation of these images shall be restricted to “global” changes only.
A.2.4 Cropping
Cropping of these images shall be permitted so long as the appropriate image colour space identifier is
included as part of, or with, the images.
A.3 Guidelines for distribution and sharing
A.3.1 General
Many of the intended uses of these images require that they be used at several locations and/or by several
participants in test programs. The following uses have been interpreted to be acceptable and allowable by ISO.
A.3.2 For-profit sale
Neither the data, nor images printed from these data, shall be sold “for-profit” except as defined in A.3.3.
A.3.3 Test and evaluation packages
It shall be permitted to include the data corresponding to these images, or derivations of these images, as part
of test and evaluation packages to be sold or provided free of charge where an authentic copy of this part of
ISO 12640 is included as part of the complete package.
12 © ISO 2007 – All rights reserved

NOTE It is recognized that certain test and evaluation packages that will make use of these images might need to
embed the data to be used within other data processing procedures. The inclusion of an authentic copy of this part of
ISO 12640, obtained from the appropriate standards agency, as part of the package will allow the inclusion of similar or
derived data as needed within the package.
A.3.4 Test and evaluation programs
Copies of these data files, or derivative files, may be exchanged between participants in test and evaluation
programs. The sponsoring organization shall be capable of showing ownership of an authentic copy of this
part of ISO 12640.
A.3.5 Reports
It shall be permitted to display these images as part of the report of test programs, or in advertisements, as
long as the organization sponsoring the display is in possession of an authentic copy of this part of ISO 12640.

Annex B
(informative)
Definition of the reference colour gamut
B.1 Development of the reference colour gamut
The reference colour gamut defined for this part of ISO 12640 was derived from three different colour gamuts
developed quite independently, but for similar reasons. The first was developed within ISO/TC 130 in order to
provide an estimate of the gamut of surface colours for the purposes of this part of ISO 12640. The second
was produced by Hewlett-Packard as the gamut of colours produced by all colour printers, during their own
product development work, and offered to the International Color Consortium (ICC) as a reference colour
gamut for the Profile Connection Space for perceptual renderings defined in ICC.1:2004-04. It was also
offered to ISO/TC 130 for consideration in the definition of the reference gamut required for this part of
ISO 12640. During the development of this standard another useful gamut was brought to the attention of the
committee. This is a gamut known as PhotoGamutRGB, which is based on measurement of the results
obtained from silver halide printers used for producing photographic prints from digital photographs.
On review it became clear that, although there were some differences, there was also considerable similarity
between these gamuts. So, it was agreed by the committee that the data from the three sources could be
reconciled in order to produce the single reference colour gamut defined for this part of ISO 12640. This
reconciliation is described in B.5. However, for information purposes, the derivation of each of the gamuts is
briefly described.
B.2 Gamut of surface colours
The initial specification for the reference colour gamut for this part of ISO 12640 was obtained by finding the
maximum gamut obtainable with surface colours, according to the published data available to the committee
[7] [5]
in 1998. The main sources of this data were the Pointer gamut, data for Pantone colours, the SOCS data
and data for photographic media available to the committee. Some additional samples were also measured.
[7]
In 1980, Pointer published an investigation of the gamut of real surface colours , in which colour data was
analysed from the following sources:
⎯ 768 colours from the Munsell Limit Color Cascade;
⎯ 310 colours from the Matte Munsell Atlas;
⎯ 1 393 colours from ink and paint samples, textiles, coloured plastics and papers (measured in the
[7]
investigation );
⎯ 1 618 colours describing flower colours (tabulated by the Royal Horticultural Society).
Altogether, the colour coordinates of 4 089 colours were available.
[7]
Pointer combined these colour data and published the maximum chroma value at 36 hue angles and
16 lightness levels. However, the Pointer gamut data refer to CIE standard illuminant C, whereas the
committee needed the gamut with respect to illuminant D50. The Pointer gamut boundary data was therefore
converted to that for D50 using the Bradford chromatic adaptation conversion used in CIECAM97s. The D50
Pointer data were then combined with other colour data exhibiting high chroma values. In particular, the data
for 1 025 Pantone colours, a series of new colour data measured from printed samples and the colorimetric
[5]
data from the SOCS data set (ISO/TR 16066 ) were included.
14 © ISO 2007 – All rights reserved

From these XYZ data the colour gamut was calculated as a convex hull and then transformed into the CIELAB
colour space. Table B.1 shows the maximum chroma value obtainable with surface colours for 36 hue angles
and 19 lightness levels calculated as a convex hull for illuminant D50 and the 1931, 2°, standard colorimetric
observer.
*
Table B.1 — Gamut of surface colours: Maximum chroma value ( C ) with respect to
ab
*
lightness (L ) and hue angle (h )
ab
*
*
Maximum C for L =
ab
h
ab
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
0° 30 42 49 56 63 70 77 80 82 83 84 82 72 60 48 37 26 16 6
10° 28 40 48 56 63 70 77 80 82 82 83 82 75 63 51 39 28 16 6
20° 25 40 49 57 64 72 79 83 84 84 85 84 79 67 55 42 30 18 6
30° 17 34 51 60 68 77 85 88 89 88 89 88 86 74 61 48 34 20 7
40° 13 26 39 52 65 78 90 96 97 96 95 93 93 85 71 56 40 24 9
50° 11 22 33 43 54 65 75 85 95 99 102 100 98 94 87 69 49 29 11
60° 10 19 29 38 48 57 66 74 83 91 98 104 107 105 97 84 59 35 13
70° 9 18 26 35 43 52 60 68 75 82 89 96 102 108 113 99 77 44 16
80° 8 17 25 33 41 49 56 63 70 77 83 89 95 101 106 112 104 64 20
90° 8 16 25 32 40 47 54 61 68 74 79 85 91 96 102 107 112 113 30
100° 8 17 25 32 40 47 53 60 66 72 77 83 88 93 98 103 108 96 43
110° 9 17 25 33 41 48 54 60 66 72 77 83 88 93 98 99 94 67 25
120° 9 18 27 35 43 50 57 63 68 74 80 85 91 97 97 90 77 47 17
130° 10 21 30 39 47 55 61 67 73 79 85 91 97 100 91 82 62 37 14
140° 12 24 34 43 50 57 63 70 76 82 87 92 93 90 86 78 52 30 11
150° 14 28 39 48 54 61 68 75 81 88 93 91 87 83 75 66 45 26 9
160° 16 31 44 53 61 68 75 82 87 92 92 89 84 75 68 58 40 23 9
170° 17 34 49 60 70 73 76 79 83 88 86 83 78 70 62 53 38 22 8
180° 16 33 47 59 67 69 73 77 82 86 83 80 73 67 59 50 36 21 8
190° 16 31 43 53 60 63 67 71 75 78 77 75 69 64 56 48 35 21 8
200° 16 30 41 48 54 59 63 67 71 72 71 70 65 60 54 47 36 21 8
210° 16 29 38 44 51 56 60 64 68 68 68 66 62 57 51 44 35 22 8
220° 17 29 37 43 49 55 59 63 66 66 66 65 61 56 50 42 34 23 8
230° 18 30 36 42 48 54 60 64 66 66 66 65 61 56 50 42 33 23 9
240° 20 31 37 43 49 55 61 67 67 68 68 67 62 56 49 41 33 24 11
250° 22 32 38 45 51 57 63 68 70 71 68 63 58 52 45 38 31 24 14
260° 25 34 41 48 54 61 66 71 71 70 66 61 55 50 43 37 30 23 17
270° 29 38 46 53 61 67 72 73 73 71 66 60 54 49 42 35 29 22 14
280° 36 45 53 62 70 76 77 78 78 73 66 60 54 49 42 35 29 22 10
290° 45 56 67 77 84 84 83 83 80 75 68 62 56 50 43 36 29 22
...