Conference PaperPDF Available

Is it really true that Pantone Extended Gamut can reproduce 90% of all Pantone Spot Colors?

Authors:
  • Danish School of Media and Journalism, Copenhagen, Denmark

Abstract

This study seeks to confirm or refute the statement that Pantone Extended Gamut (XG) can reproduce 90% of all Pantone Solid colors (PMS) by using seven process colors (CMYK+OGV). At the same time, it is investigated which colors within the 10% that cannot be reproduced in this system. By using a comparison of Pantone's own "reference values" (CIELAB values) it appears that only 57.6% of all PMS colors can be reproduced if the tolerance is ≤ 2 DE2000 and only 82.7% of all PMS colors can be reproduced if the tolerance is ≤ 3 DE2000. The tolerance will have to be ≤ 3.7 DE2000 in order to reproduce 90% of all PMS colors. In an attempt to plot the two gamuts in a CIE a* b* projection diagram, it proves surprisingly difficult to identify the seven primary colors of XG. PMS Orange 021 is apparently not equal to XG Orange. PMS Green is apparently not equal to XG Green, and PMS Violet is apparently not equal to XG Violet. Likewise, it has not been possible to identify the secondary colors (overprints) of the XG Primary Colors. A suggestion for gamut plotting is proposed.
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Is it really true that Pantone Extended Gamut can reproduce 90% of all Pantone
Spot Colors?
Michael Abildgaard Pedersen
The Danish School of Media and Journalism, Department of Media Production and Management,
Copenhagen.
map@dmjx.dk
Short Abstract
This study seeks to confirm or refute the statement that Pantone Extended Gamut (XG) can reproduce
90% of all Pantone Solid colors (PMS) by using seven process colors (CMYK+OGV). At the same time,
it is investigated which colors within the 10% that cannot be reproduced in this system. By using a
comparison of Pantone's own "reference values" (CIELAB values) it appears that only 57.6% of all PMS
colors can be reproduced if the tolerance is 2 DE2000 and only 82.7% of all PMS colors can be
reproduced if the tolerance is 3 DE2000. The tolerance will have to be 3.7 DE2000 in order to
reproduce 90% of all PMS colors. In an attempt to plot the two gamuts in a CIE a* b* projection diagram,
it proves surprisingly difficult to identify the seven primary colors of XG. PMS Orange 021 is apparently
not equal to XG Orange. PMS Green is apparently not equal to XG Green, and PMS Violet is apparently
not equal to XG Violet. Likewise, it has not been possible to identify the secondary colors (overprints) of
the XG Primary Colors. A suggestion for gamut plotting is proposed.
Keywords: Extended gamut, Pantone XG, CIELAB, DE2000
1. Introduction and background
In the Graphic Arts Industry, it’s a well-known fact that only 50% of all Pantone Solid Colors can be
reproduced by using the four process colors CMYK. Therefore, years of efforts have been made to
expand the CMYK gamut. Either by producing more pigmented CMYK inks (CMYK+) or by expanding
to six-colors Hexachrome (CMYKOG), seven-color Hi-Fi Color (CMYKRGB) or seven-color Opaltone
(CMYRGBK).
In 2015, Pantone released a concept called Pantone Extended Gamut (XG) claiming to be able to
reproduce 90% of all Pantone colors by using the seven process colors Cyan, Magenta, Yellow, Black,
Orange, Green and Violet (Pantone.com).
In 2019, a study by Ryerson University confirmed that Pantone XG "are able to reproduce more than
90% of the Pantone spot color library on the Epson P9000 inkjet printer to < 2 CIEDE2000" (Sharma,
A. 2019)
The Pantone XG fan contains 1,729 PMS Colors matched by using the XG seven-color printing process.
Nevertheless, when looking through the colors and comparing them with the original PMS spot colors,
it turns out that many of the colors cannot be matched with a visually satisfactory result.
This raises several questions, for example:
If Pantone XG can match 90% of all PMS Colors, which PMS colors cannot be reproduced and how
would it be possible to identify those missing 10%?
2. Materials and Methods
Four abbreviations will be used in the rest of this Paper:
XG meaning Pantone Extended Gamut Coated (Pantone 2015)
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PMS meaning Pantone Formula Guide Solid Coated (Pantone 2019)
PCMS meaning Pantone Color Manager Software v2.4.0.60 for Windows (Pantone 2020)
CMYK meaning Process Colors as defined in ISO 12647-2:2013 on Coated paper
Colorimetric data from all Pantone Colors (PMS and XG) were downloaded from PCMS. These were
imported into excel, where additional colorimetric data were calculated (L*, a*, b*, C*, h*, H*,
Eab and E00). This way, data could be sorted by color difference.
A visual assessment was made of the individual Pantone color pairs PMS vs. XG in a viewing booth
under daylight D50. Color pairs with a clearly color difference were noted and plotted into a CIE a* b*
diagram. This was conducted by following Pantone's instructions (Pantone 2015, p.ii).
The XG fan deck (printed in 2015) were purchased, unpacked, put to use in 2020 and measured in 2021.
The XG Primary colors Orange, Green and Violet from the XG fan deck were measured by using an X-
rite eXact Advanced spectrophotometer set in accordance with ISO 12647-2:2013, Table 2, page 6 using
M1.
The assessment of whether XG can reproduce PMS is based on a comparison of Pantone's own reference
values for the two color systems.
When assessing color differences, a tolerance of 3 DE2000 was used as the limit (Pedersen 2016)
An attempt to identify XG's seven primary colors and their secondary colors was made in order to plot
gamuts into the CIE a* b* diagram to identify possible gab areas between PMS and XG gamuts.
3. Results and Discussion
3.1 Colorimetric Reference Value Comparison
By sorting the 1,729 data pairs by DE2000, it appears that 82.7% of the color pairs have a DE2000 ≤ 3
(1,432 color pairs). Thus, XG cannot reproduce 90% of PMS if the tolerance is 3.0 DE2000. 327 color
pairs have a color difference > 3.0 DE2000 (19% of all colors).
Figure 1: Colorimetric data in Excel sorted by DE2000 (showing five of the 1,729 color pairs)
In order to claim that XG can reproduce 90% of PMS colors, a tolerance of 3.7 DE2000 have to be
the limit. This way, 1,556 PMS colors can be reproduced by XG leaving 173 colors, which cannot.
By maintaining the limit of 3 DE2000 there will be 297 PMS colors that cannot be reproduced by XG
and the Excel sheet shows which PMS colors are out of XG gamut.
Other observations show that the largest color difference is 9.2 DE2000 (PMS252), the smallest color
difference is 0.1 DE2000 (PMS7476 and 7719) and 19.2% (322 colors) have a DE2000 ≤ 1.
3.2 Gamut sizes
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To get the first indications of the difference in gamut sizes between the two gamuts, the range of each
gamut is shown in Table 1.
Table 1: Comparison of the two color space's (PMS and XG) colorimetric extreme values
The span of the PMS gamut
The span of the XG gamut
L*
from 7.90 (Black6C) to 92.10 (600C)
from 9.48 (7447XGC) to 92.03 (600XGC)
a*
from -78.99 (3405C) to 80.21 (226C)
from -77.70 (2252XGC) to 77.34 (219XGC)
b*
from -75.99 (072C) to 110.86 (Yellow C)
from -70.22 (2371XGC) to 95.13 (1505XGC)
C*
from 0.20 (CoolGray4) to 110.90 (Yellow C)
from 9.69 (7547XGC) to 98.39 (3405XGC)
It seems that XG is less chromatic in the yellowish areas. The most chromatic color in PMS is Yellow
C while the most chromatic color in XG is orange 1505 XG. A mapping of the gamuts might provide
further information.
3.3 Gamut mapping
In order to plot an XG gamut as a polygon in a CIE a*b* projection diagram a minimum 12 data points
would be desirable. Six primary colors (CMYOGV) and six secondary colors (Y+O, O+M, M+V, V+C,
C+G, G+Y). This will create a 12-sided polygon.
3.3.1 Primary XG Color identification
Surprisingly it has not been possible to find precise and specific information on the XG Primary Colors
Orange XG, Green XG and Violet XG. Neither in the XG fan deck nor at Pantone Inc.
A search for CIELAB-values (the “Reference values”) from the PCMS results in confusion information
and the subsequent measurements of the colors in the XG fan deck causes further confusion.
One would assume that it would be relatively easy to figure out which seven Pantone XG primary inks
to use. It would be logical to use the four common CMYK Process Colors, PMS Orange 021, PMS
Green and PMS Violet. However, it does not seem to be these inks sets.
Page 1XG in the XG fan deck (Pantone 2015), shows the seven Pantone XG Bases Colors. The four
process colors CMYK are simply named Process Yellow C, Process Magenta C, Process Cyan C and
Process Black C (XG is not a part of the names). The additional base colors are named XG Orange C,
XG Green C and XG Violet C.
On page iii, in the XG fan deck it states that the Primary XG-CMYK colors must comply with ISO
12647-2:2004/Amd 1:2007. This information is surprising since ISO 12647-2 came in a new edition in
2013 (ISO 12647-2:2013) prior to the production of the XG fan deck in 2015. In this research, the new
edition of ISO is used.
This however, defines four of the seven XG Process Colors (CMYK) and at the same time sets the limits
for how many PMS colors can be reproduced in this part of the XG gamut when it comes to PMS colors
created by CMYK combinations, including its overprint RGB.
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Table 2: Colorimetric values of XG CMY Primaries
ISO 12647-2:2013
L*
a*
b*
XG Hue angle
C* (calculated)
Cyan
56
-36
-51
233°
62.43
Magenta
48
75
-4
357°
75.11
Yellow
89
-4
93
93°
93.09
Consequently, a yellow PMS spot color must have a maximum chroma (C*) of 93.09 and other
yellowish spot colors must have a smaller chroma (C*) to be within this XG-CMY-gamut. This means
that PMS Yellow (C*110.87) and PMS Yellow 012 (C*109.07) cannot be reproduced in this XG-CMY
gamut and thus cannot be reproduced in XG.
Having the three chromatic CMY XG-Process Colors defined, we need to define the three additional
XG Process Colors; XG Orange, XG Green and XG Violet.
On page iii, in the XG fan deck (Pantone 2015) there are additional information about the colors metric
hue angles (Orange 58°. Green 180° and Violet 311°). A search for these three additional primary colors
inside the XG fan deck results in the following confusing observations: One would assume that the
primary color XG Orange should consist of 100% Orange and no other XG colors and it should have a
hue angle of 58°. None of the colors inside the XG fan deck complies with this. The only XG color
named orange is Orange 021 XG (Pantone 2015, p.23). This however, is created by a combination of
27% Magenta + 100% Orange in the XG fan deck, it has a hue angle of 54° and therefore the primary
XG Orange doesn’t seem to be PMS Orange 021.
It turns out that another orange color 1505 XG is the only XG color to meet the requirement (O: 100%
+ no other XG colors) and it has a hue angle of 59°. Thus, PANTONE XG Orange could be equal to
PMS 1505 C. According to the PMS fan deck, PMS 1505 is created by 50% Orange 021 + 50%
Transparent White!
Table 3: XG Orange and Orange 021 comparison of different target values
L*
a*
b*
C*
h*
PMS Orange 021
PMS 1505
XG Orange
Measured on page 1XG
66.02 56.06 91.01 106.89 58.37 7.1 ∆E2000 0.9 ∆E2000
Orange 021 XG
Values from PCMS
50.82 61.70 86.47 106.22 54.49 2.0 E2000
PMS Orange 021
Values from PCMS
60.81 65.69 85.06 107.47 52.32
Likewise, we would assume that the primary XG Green should consist of 100% Green and no other XG
colors. It should have a hue angle of 180°. However, none of the 1,729 XG colors has these
specifications! The closest color is 2240 XG (86% Green (h* 181)) or 3275 XG (23% Cyan + 92%
Green (h*185)). In fact, XG Green is defined with the combination; C:26% + Y:17% + G:100% (Pantone
2015, p.177). Even though it has a correct hue angle of 179.5° it does not make sense that a primary
process color should be made from a screening combination of three other primary process colors.
Nevertheless, the target values from PCMS indicate that PMS Green is the Primary XG Green.
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Table 4: XG Green and PMS Green comparison of different target values
L*
a*
b*
C*
h*
PMS Green
PMS 2240
PMS 3275
XG Green
Measured on page 1XG
62.20 -74.87 0.67 74.87 179.49 4.0 ∆E2000 4.2 ∆E2000 3.6 ∆E2000
Green XG
Values from PCMS
57.82 -76.17 0.67 76.17 179.50 0.3 ∆E2000
PMS Green
Values from PCMS
57.74 -77.18 0.20 77.18 179.85
Finally, the primary process color XG Violet should consist of 100% Violet and no other XG colors. It
should have a hue angle of 311°. However, XG Violet is defined as 37% Cyan + 100% Violet (Pantone
2015, p.96) it has a hue angle of 307.70°. Thus, PMS Violet doesn’t seem to be the XG Primary Violet.
Pantone 266 XG is defined as 80% Violet (XG p.94), it has a hue angle of 308.68° and is thereby the
closest XG color to 100% Violet. A comparison of the CIELAB target values from XG Violet and PMS
Violet from PCMS results in a ∆E2000 of 3.3 and thereby indicate that PMS Violet could be the primary
process color XG Violet even if it exceeds the limit of 3 DE2000. However, when comparing the
measurement of the XG Violet from the fan deck and the target values from PCMS there is a difference
of 6.1 DE2000 as seen in Table 5. This in fact indicates that PMS Violet cannot even be reproduced in
XG even though Violet is a primary color in XG!
Table 5: XG Violet and PMS Violet comparison of different target values
L*
a*
b*
C*
h*
PMS Violet
PMS 266
XG Violet
Measured on page 1XG
25.94 52.05 -59.31 78.91 311.27 6.1 ∆E2000 10.6 ∆E2000
XG Violet
Values from PCMS
22.92 49.26 -63.74 80.56 307.70 3.3 ∆E2000
PMS Violet
Values from PCMS
18.75 54.58 -69.48 88.35 308.15
3.3.2. Secondary Colors
Secondary colors are usually made of two primary colors (100%+100%). In the XG fan deck, only one
color is made from two primary inks (2371 XG: V:100% + C:100% (Pantone 2015, p.109)) none of the
other 1,729 XG colors is made solely from two solid primaries.
Thus, in order to plot the gamut edge, alternative secondary colors must be specified. It should be colors
that lie between two primary colors, which have the highest possible chroma (C*) and having a mixing
ratio as close to 50/50 as possible. A proposal is shown in Table 6.
Table 6: Possible alternative Secondary Colors for plotting XG
The color between:
XG Name
XG Process combination
L*
a*
b*
C*
Yellow and Orange
XG 2013
Y:100 + O:54
75,48
32,35
92,03
97.55
Orange and Magenta
XG 2347
O: 100% + M: 83%
49,51
72,43
67,72
99,16
Magenta and Violet
XG 2405
M:100% + V:49%
38,69
65,70
-12,99
66,98
Violet and Cyan:
XG 2371
V:100% + C:100%
18,72
42,30
-70,22
81,98
Cyan and Green
XG 320
C:90% + G:75%
52,48
-62,53
-24,25
67,06
Green and Yellow
XG 2423
Y:100% + G:91%
61,74
-71,90
47,15
85,98
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This way, it is now possible to plot an XG gamut into the CIE a*b* projection diagram (Figure 2, bold
line). For the sake of comparison, other gamuts have been plotted in Figure 2. In an earlier study, the
PMS gamut was specified (Pedersen 2019) and is plotted as a bold dotted line. The CMYK gamut (thin
line) relate to ISO 12647-2:2013 and the RGB gamuts (thin dotted lines) were plotted by using CIELAB
values from the primary RGB and their secondaries.
Figure 2: Comparison of five different color spaces and the gabs between PMS and XG
Figure 2 confirms some of the assumptions discussed in section 3, regarding the yellowish area. In
addition, it also show a gap between PMS and XG in the purplish area. By consulting all reference
values from PCMS imported into the Excel spreadsheet it shows that colors with the largest color
difference are placed in this purplish area. Some examples below:
PANTONE 252 (9.2 DE2000)
PANTONE Purple (8.7 DE2000)
PANTONE 2582 (8.1 DE2000)
PANTONE 2375 (7.7 DE2000)
PANTONE 2385 (7.7 DE2000)
PANTONE 251 (7.4 DE2000)
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PANTONE 253 (7.4 DE2000)
PANTONE 2572 (7.1 DE2000)
PANTONE 246 (7.0 DE2000)
Forty other PMS colors in this area have a difference between 5.0 and 6.9 DE2000.
4. Conclusions
The question of whether Pantone Extended Gamut (XG) can reproduce 90% of all PMS colors depends
largely on which tolerance limit is used and on which basis the comparison is made.
When the Ryerson study determines that 90% of all PMS colors can be reproduced to a color difference
of 2 DE2000 (Sharma, A. 2019, p. 4), this is based on an assessment of the ability of different software
solutions to separate digital colors into the seven process colors and a subsequent digital print
production.
In the present study, an assessment and a comparison has primarily been made of Pantone's own target
values for the two color systems (CIELAB target values from PMS Solid Coated vs XG Coated).
On this basis, the conclusion is that according to Pantone's own target values it is not possible to
reproduce 90% of all the PMS colors. According to these data, only 82.7% of the colors can be
reproduced to a limit of 3 DE2000. If the tolerance limit is to be lowered to 2 DE2000, as the Ryerson
study has used, only be 57.6 % of all PMS colors can be reproduced.
As for the 10% of the color pairs with highest color difference, the majority are located in the purplish
area while some highly chromatic red and yellow colors also outside the gamut.
References
ISO 12647-2:2013 Graphic technology Process control for the production of half-tone colour
separations, proof and production prints - Part 2: Offset lithographic processes. Geneva: ISO Central
Secretariat.
Pantone, 2015. Pantone Extended Gamut Coated the Plus Series 1,729 PANTONE MATCHING SYSTEM
Colors matched using a seven-color printing process. New Jersey: Pantone LLC
Pantone, 2019. Pantone Formula Guide Solid Coated. Ink colors and formulas for packaging, print and
graphics. New Jersey: Pantone LLC
Pantone, 2020. Pantone Color Manager Software, version 2.4.0.60 for Windows. New Jersey: Pantone LLC
Pedersen, M. A. 2016. Why most Brand Manuals fail when it comes to defining Brand Colors. And how to
determine acceptable Color Deviations for specific Brand Color. Advances in Printing and Media
Technology, Vol. XLIII(III) p.91100. Toronto: iarigai
Pedersen, M. A. 2019. Reinventing the wheel. An attempt to create an objective technical color wheel for
Pantone colors by using hue angles (hab) as the deciding factor. Advances in Printing and Media
Technology, Vol. XLVI(VI) p.29-41. Stuttgart: iarigai
Sharma, A. 2019. Ryerson University Expanded Gamut Study 2019. Evaluation of Spot Color Reproduction
in Multicolor Printing. Version 2.7.9 September. Toronto: Ryerson University.
Prinng in the Digital Era
Proceedings of the 47th Annual scienc conference of the iarigai
ISBN: 978-618-81734-3-9
September 2021, Athens, Greece
Copyright: iarigai - the Internaonal Associaon of Research Organizaons
for the Informaon, Media and Graphic Arts Industries
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Presentation
Full-text available
The specification of Brand Colors in Brand Manuals and determination of acceptable color differences
Pantone Extended Gamut Coated the Plus Series 1,729 PANTONE MATCHING SYSTEM Colors matched using a seven-color printing process
  • Pantone
Pantone, 2015. Pantone Extended Gamut Coated the Plus Series 1,729 PANTONE MATCHING SYSTEM Colors matched using a seven-color printing process. New Jersey: Pantone LLC
Pantone Formula Guide Solid Coated. Ink colors and formulas for packaging, print and graphics
  • Pantone
Pantone, 2019. Pantone Formula Guide Solid Coated. Ink colors and formulas for packaging, print and graphics. New Jersey: Pantone LLC
Pantone Color Manager Software, version 2.4.0.60 for Windows
  • Pantone
Pantone, 2020. Pantone Color Manager Software, version 2.4.0.60 for Windows. New Jersey: Pantone LLC
Ryerson University Expanded Gamut Study 2019. Evaluation of Spot Color Reproduction in Multicolor Printing
  • A Sharma
Sharma, A. 2019. Ryerson University Expanded Gamut Study 2019. Evaluation of Spot Color Reproduction in Multicolor Printing. Version 2.7.9 September. Toronto: Ryerson University.