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I'm trying to create a color scheme for latex/beamer/pdf that matches my university's official corporate style. (But this question is not about latex/beamer!) The material I have to work with is a PDF file describing the style, and an EPS file containing the logo.
According to the style description, the main color is Pantone 1797 C, used both for headlines in printed materials and within the logo. The style description contains the following information:
Pantone 1797 C, CMYK: 2 98 85 7, RGB: 192 15 34, HEX: #C00F22
Since I'm working on slides to be presented with a PDF viewer on a computer screen / projector, I'm mainly interested in how this color is supposed to render there, i.e. as which RGB triplet.
In understand that this is a spot color for print which has only an approximation in CMYK, which in turn can in different approximate ways be converted to RGB, but still I would expect some consistency, say, with respect to the sRGB color space standard for display devices.
Now, I looked up the color on Pantone's color finder, and their information is different:
Pantone 1797 C, CMYK: 0 92 72 6, RGB: 203 51 59, HEX: #CB333B
Hm, why does my university disagree with the designers of the color?
Dec 16: I now understand that the university's values are based on the Pantone "Color Bridge Guide" using the M1 lighting standard, while the "Color Finder" uses the M2 lighting standard. The question below regarding rendering inconsistency is still open though.
The style-guide PDF contains examples of the color, so to resolve this ambiguity I thought I'd look at how it is rendered in (Linux) PDF viewers, picking the RGB color from the screen (with KColorChooser). Unfortunately, many of them do different things, sometimes strongly different:
Adobe Reader v9.5.5: #E80014
Foxit Reader v2.4.4: #DA2131
Google Chrome v79: #DB1E30
Firefox v68.3: #F02E29
qpdfview v0.4.17: #DC1B30
MuPDF v1.14: #DC1B30
Okular v1.3.2: #DC1B30
Zathura v0.3.2: #DC1B30
The Linux-native viewers do all the same thing (#DC1B30), I guess because they use the same rendering library (Poppler). The color is similar in Foxit Reader and Google Chrome, but Adobe Reader and Firefox differ significantly. And, none of these colors are anywhere near the offical RGBs stated by the university or by Pantone.
Well, since the rendering results don't help, let's see how the color is specified in the PDF itself. When I open the style-guide PDF in Inkscape v0.92.4 and GIMP v2.10.8 and examine the respective page element, I get slightly different RGB triplets (#DC1B30 and #DC1A30) but the same CMYK values, 0 88 78 14. Great! Unfortunately, they again differ substantially from the official values.
Dec 16: I was now able to analyze the PDF code using pdf-parser.py, see this answer to another question. The color coded in there is CMYK
2 98 85 7, in line with the university's description. The color space isDeviceCMYK. There are two ICC color profiles embedded, both for "Adobe RGB (1998), irrelevant as far as I can tell. So I guess it comes down to the question: Why is DeviceCMYK apparently interpreted differently by different PDF viewers? And why do Inkscape and GIMP show0 88 78 14instead?
But I also have the logo EPS. Rendering it with Okular results in #DA2131. Wow, that matches... the PDF render by Foxit Reader. Opening the EPS in Inkscape gives rendered #DB1B30 and encoded CMYK 0 88 78 14.
And as a last resort, I convert the EPS logo to PDF using epstopdf (based on Ghostscript v9.27), and repeat the whole thing. Result:
Adobe Reader v9.5.5: #DB2132
Foxit Reader v2.4.4: #DA2131
Google Chrome v79: #DB1E30
Firefox v68.3: #F02E29
qpdfview v0.4.17: #DB1B30
MuPDF v1.14: #DB1A30
Okular v1.3.2: #DB1B30
Zathura v0.3.2: #DC1A30
Inkscape v0.92.4: #DB1B30
GIMP v2.10.8: #DC1A30
You may notice that now Adobe Reader approximately agrees with the other programs, but Firefox prefers to stay different.
To summarize, I obtained 12 different hex triplets for one and the same color. There is some tendency towards #DB1E30, but unfortunately that disagrees with what either the university or Pantone say.
How is Pantone 1797 C supposed to be rendered on a computer screen?!
Oh, and did I mention that there are 6 other Pantone colors in the corporate style?
A. Donda
Posted 2019-12-14T23:06:34.217
Reputation: 660
“…picking the RGB color from the screen…” Depending on what OS you are using and what software you are using, when a PDF/EPS is rendered, the color might be adjusted for display. Thus digital eyedropper measurements might not match exactly. If you have the ability to disable color profiles in whatever PDF viewer you are using, try doing that and then do another round of digital eyedropper measurements. – JakeGould – 2019-12-14T23:29:02.140
@JakeGould, yes, I looked for that, but I'm afraid that none of the viewers available to me have configurable color profiles. And shouldn't screen display always use sRGB anyway? Unless I would calibrate my monitor and configure it specially. – A. Donda – 2019-12-14T23:33:07.277
I though it would be more about color profiles in the files, and whether or not the viewers interpret them. Which is why I expected two different outcomes: When the viewer uses the embedded color profile, and when it didn't. – A. Donda – 2019-12-14T23:33:51.220
Well, does your university have any branding or usage guidelines? Or perhaps a staff that can help you iron this out? I can’t imagine you are the first person to stumble into a scenario like this? – JakeGould – 2019-12-14T23:42:43.033
They do, but this is only tangentially about the guidelines. Even if I would have the right color information from them, it still wouldn't render reliably. Moreover, I very much suspect I'm the first person pedantic enough about shades of red. I had to exchange about 10 emails with them before I even got the logo EPS. – A. Donda – 2019-12-14T23:45:15.053
1I've updated the question with some additional information. – A. Donda – 2019-12-16T19:05:10.533
Looks good! But honestly might not be answered here since this is more about a graphic design production flow. I would recommend looking around the Graphic Design SE site to see if this question is covered there. If not, I would recommend you deleting this question and just reposting it there.
– JakeGould – 2019-12-16T21:34:10.943@JakeGould, you're right. I did search all SE sites first though, and didn't find anything. What I did find is that most questions about PDF technicalities are on SO, so that might be a match. I just fear that there it would be rejected because it has no obvious relation to programming. Unless PDF itself would be regarded as a programming language. – A. Donda – 2019-12-16T22:02:21.090