All, I used the very useful colorspace package for the plots in my book (pdf available here): http://knosof.co.uk/ESEUR/ The color makes the plots look great, on screen. To get lots printed, the printer requires converting the images to use cmyk (a common requirement for larger printers, I'm told). See page 11 here: https://www.ingramspark.com/hubfs/downloads/file-creation-guide.pdf No problem, the script below uses ghostscript to achieve this: gs -o ESEUR-cmyk.pdf \ -sDEVICE=pdfwrite \ -sProcessColorModel=DeviceCMYK \ -sColorConversionStrategy=CMYK \ -sColorConversionStrategyForImages=CMYK \ ESEUR.pdf the problem is that the converted colors don't look nearly as good. For instance the cyan now looks blue, and prints as pure blue. I can regenerate the images, and explicitly specify cmyk. But using: pdf.options(colormodel="cymk") does not change anything. The colors look remarkably similar to those produced via the ghostview route. I have been looking at color profiles and trying to find a way of modifying an ICC profile (yes, it looks difficult). Does anybody have any ideas for producing cmyk images that have the same (or close enough) look as the RGB?
RGB -> CYMK, with consistent colors
6 messages · Martin Møller Skarbiniks Pedersen, Derek M Jones, Derek Jones +2 more
On Sun, 29 Nov 2020 at 14:26, Derek Jones <gmane at knosof.co.uk> wrote:
[...]
I can regenerate the images, and explicitly specify cmyk. But using: pdf.options(colormodel="cymk") does not change anything. The colors look remarkably similar to those produced via the ghostview route.
[...]
Does anybody have any ideas for producing cmyk images that have the same (or close enough) look as the RGB?
Have you tried printed a few pages in CMYK? A monitor is based on mixing light using Red-Green-Blue. So it is not possible for the monitor to show CMYK which must be printed on paper to view correctly. Regards Martin
Martin,
Have you tried printed a few pages in CMYK? A monitor is based on mixing light using Red-Green-Blue. So it is not possible for the monitor to show CMYK which must be printed on paper to view correctly.
Yes, I have printed some 'CMYK' pages. The blue is very obviously not cyan, as compared to printing the RGB version.
Derek M. Jones Evidence-based software engineering tel: +44 (0)1252 520667 blog:shape-of-code.coding-guidelines.com
Martin,
Have you tried printed a few pages in CMYK? A monitor is based on mixing light using Red-Green-Blue. So it is not possible for the monitor to show CMYK which must be printed on paper to view correctly.
Yes, I have printed some 'CMYK' pages. The blue is very obviously not cyan, as compared to printing the RGB version.
Let me correct the last sentence.
The printed blue is obviously not cyan when printing 'rgb' and 'cmyk'
pages.
Somebody pointed out in an email that probably I am the only one who
is going to notice the difference, and he may be right.
My frustration is that the printer supports cyan as a base color.
I understand that rgb->cmyk involves lots of variables, and I'm hoping
that somebody will point me at one that allows me to tweak the output.
library("colorspace")
two_c=rainbow(2)
x=runif(20)
y=runif(20)
plot(x, y, col=two_c[2])
pdf(file="cmyk.pdf", colormodel="cmyk")
plot(x, y, col=two_c[2])
dev.off()
I had a long discussion on this topic with the Springer production group when my book was in production. Statistical Analysis and Data Display: An Intermediate Course with Examples in R, second edition Richard M. Heiberger and Burt Holland. https://www.springer.com/gp/book/9781493921218 As I now understand it, the physical inks used in printing cannot produce the same range of colors as the computer screens. The issue is not the notation, but rather the underlying technology. I chose to let the publisher make the conversion. I looked at the set of pdfs for your book, and to anyone else but you, I think they would look fine in slightly different colors. Rich
On Sun, Nov 29, 2020 at 8:26 AM Derek Jones <gmane at knosof.co.uk> wrote:
All, I used the very useful colorspace package for the plots in my book (pdf available here): http://knosof.co.uk/ESEUR/ The color makes the plots look great, on screen. To get lots printed, the printer requires converting the images to use cmyk (a common requirement for larger printers, I'm told). See page 11 here: https://www.ingramspark.com/hubfs/downloads/file-creation-guide.pdf No problem, the script below uses ghostscript to achieve this: gs -o ESEUR-cmyk.pdf \ -sDEVICE=pdfwrite \ -sProcessColorModel=DeviceCMYK \ -sColorConversionStrategy=CMYK \ -sColorConversionStrategyForImages=CMYK \ ESEUR.pdf the problem is that the converted colors don't look nearly as good. For instance the cyan now looks blue, and prints as pure blue. I can regenerate the images, and explicitly specify cmyk. But using: pdf.options(colormodel="cymk") does not change anything. The colors look remarkably similar to those produced via the ghostview route. I have been looking at color profiles and trying to find a way of modifying an ICC profile (yes, it looks difficult). Does anybody have any ideas for producing cmyk images that have the same (or close enough) look as the RGB?
______________________________________________ R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Hi. CMYK and RGB are physically different concepts of colour mixing (subtractive/additive) and the only way how to achieve good results is to calibrate the monitor and the printer (which is hardly achievable in home conditions). Usually DTP professionals are equipped for such kind of work. Even then, the results could be slightly different as the whole colour space is not achievable by only several (4 at least) pigments. And also colour is not simple thing but basically a process involving light, target and person who perceives it. If you insist on achieving good printed results, the best way is to print it and adjust colour(s) to be pleasing. However you cannot control others so if anybody prints your book he hardly get the same result as you. Cheers Petr
-----Original Message----- From: R-help <r-help-bounces at r-project.org> On Behalf Of Derek M Jones Sent: Sunday, November 29, 2020 7:23 PM To: Martin M?ller Skarbiniks Pedersen <traxplayer at gmail.com> Cc: R mailing list <r-help at r-project.org> Subject: Re: [R] RGB -> CYMK, with consistent colors Martin,
Have you tried printed a few pages in CMYK? A monitor is based on mixing light using Red-Green-Blue. So it is not possible for the monitor to show CMYK which must be printed on paper to view correctly.
Yes, I have printed some 'CMYK' pages. The blue is very obviously not cyan, as compared to printing the RGB
version.
-- Derek M. Jones Evidence-based software engineering tel: +44 (0)1252 520667 blog:shape-of-code.coding-guidelines.com
______________________________________________ R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting- guide.html and provide commented, minimal, self-contained, reproducible code.