Am 2018-09-30 um 15:46 schrieb Jan U. Hasecke :

Hi,

I would like to know, how to define colors to have a good printing quality.

I am currently producing print materials for a company where all colors were defined for online usage first, so we started with defining RGB colors and then derived CMYK colors.

What is the best approach for defining colors in print materials? What color model shall I use? RGB or CMYK?

For the background. We have some SVG graphics we use on the website. They are defined in RGB color model. And we use them in the print materials as well.

I tend to define RGB colors in my print documents so that the colors of the included SVG files match the defined colors I use elsewhere in the document. Eg. the Corporate-Blue of the Logo (SVG) will match the Blue of the headlines.

I could as well define CMYK colors in the document but then I have two different color models in one document and I fear that the colors are printed in different hues.

What would you do?

Hi juh, you can define colors in several color models at once; CMYK makes most sense for professional printing. e.g. \definecolor[CompanyBlue][r=0,g=0,b=1,c=1,m=1,y=0,k=0] and see https://wiki.contextgarden.net/Command/setupcolors (I would activate rgb or cmyk colors via modes, if you produce different media) CMYK colors in SVG are difficult (I needed them in 2005, nowadays there’s a hardly supported standard for icc profile based colors). e.g. https://stackoverflow.com/questions/3405689/svg-image-with-cmyk-colours-is-i... https://www.w3.org/TR/SVGColor12/#icc-colors Something about color profile handling in ConTeXt: https://wiki.contextgarden.net/PDFX Now you must decide if you want to go the PDF/X-1a route (device dependent CYMK values) or PDF/X-3 (profiled colors). Luckily I never had to match corporate colors of different models in ConTeXt... Greetlings, Hraban --- https://www.fiee.net http://wiki.contextgarden.net https://www.dreiviertelhaus.de GPG Key ID 1C9B22FD

Luckily I never had to match corporate colors of different models in ConTeXt...

On 9/30/2018 5:16 PM, Henning Hraban Ramm wrote: the worst are colors specs with 4 decimals based on some design made in indesign where one has at most 256 values per channel and then some designer looking at his display claiming to see a difference in the 3rd decimal betweenm his sample and the one generated by tex ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl -----------------------------------------------------------------

On 9/30/2018 7:22 PM, Alan Braslau wrote:

On Sun, 30 Sep 2018 19:07:24 +0200 Hans Hagen wrote:

...

...

Luckily I never had to match corporate colors of different models in ConTeXt... the worst are colors specs with 4 decimals based on some design made in indesign where one has at most 256 values per channel and then some designer looking at his display claiming to see a difference in the 3rd decimal betweenm his sample and the one generated by tex

I have 16bit grayscale images where the full dynamic range contains very useful information. Of course, no display really shows this and I doubt that any printer would faithfully reproduce it, yet the eye can discern the difference using the proper media. This is now called high dynamic range imaging in photography... but has been used in X-ray imaging for quite some time now.

given that the average male can only see 16 shades of gray ...

For reasons of quality or transparency, rather free dissemination of information, it would be useful to be able to distribute a PDF including these images with their whole 16bit dynamic range. Of course, any or most all PDF readers would only display 8bits, but one could in principal extract the underlying image for examination and analysis. c m y k in 16 bit would mean 4 * 8 bytes per pixel

(ok, one day we migh twant to store raw images made by these multi-ccd (in high end) phone camera and do all these sharp and zoom corrections outside that device .. interesting techniques btw) Hans ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl -----------------------------------------------------------------

On 10/1/2018 9:23 AM, Jan U. Hasecke wrote:

On 30.09.18 17:16, Henning Hraban Ramm wrote:

...

Hi juh,

you can define colors in several color models at once; CMYK makes most sense for professional printing.

e.g. \definecolor[CompanyBlue][r=0,g=0,b=1,c=1,m=1,y=0,k=0]

and see https://wiki.contextgarden.net/Command/setupcolors (I would activate rgb or cmyk colors via modes, if you produce different media)

I don't know how to enable this via modes.

\setupcolors[cmyk=yes,rgb=no] etc

...

CMYK colors in SVG are difficult (I needed them in 2005, nowadays there’s a hardly supported standard for icc profile based colors). e.g. https://stackoverflow.com/questions/3405689/svg-image-with-cmyk-colours-is-i... https://www.w3.org/TR/SVGColor12/#icc-colors

Something about color profile handling in ConTeXt: https://wiki.contextgarden.net/PDFX

Now you must decide if you want to go the PDF/X-1a route (device dependent CYMK values) or PDF/X-3 (profiled colors).

How can I test, what colors are used in the resulting PDF? Currently I pick the colors with a tool in Gimp to see what colors come up.

If I look at the colors this way the RGB values of the included svg are always the original values defined by the file. All other values are not the values I defined in the ConTeXt files.

I think this is due to the cmyk conversion of my screen.

\setupbackend[ format=PDF/X-3, intent=ISO Coated v2 (ECI), ]

I tried with this for example.

Anyway. Wouldn't it be better to produce a RGB-PDF and let the ripper of the print shop do the conversion? At least I can produce a RGB-PDF where all colors are defined in the same manner. it depends ... 4 channel cmyk doesn't map entirely on 3 channel rgb and vise versa

Hans ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl -----------------------------------------------------------------

On 01.10.18 10:11, Henning Hraban Ramm wrote:

If you can ensure all RGB colors are tagged with the same profiles then it should work, as long as you only care about *same* colors and not (CMYK-defined) *specific* colors...

Do your SVGs declare their RGB color space?

They start with: <?xml version="1.0" encoding="utf-8"?> <!-- Generator: Adobe Illustrator 21.0.2, SVG Export Plug-In . SVG Version: 6.00 Build 0) --> <svg version="1.1" id="Warstwa_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px" viewBox="0 0 170.1 170.1" style="enable-background:new 0 0 170.1 170.1;" xml:space="preserve"> <style type="text/css"> .st0{fill:#99BCDB;} .st1{fill:#FFFFFF;} .st2{fill:#DD4901;} .st3{fill:#327AB8;} .st4{fill:none;} .st5{clip-path:url(#SVGID_2_);} .st6{clip-path:url(#SVGID_4_);} .st7{clip-path:url(#SVGID_6_);} .st8{clip-path:url(#SVGID_8_);} </style> When I pick the screen colors with GPick I see that the SVG always stay the same. Only my colors I define with \definecolor change in the screen representation of the PDF file (as I expect).

Color management *is* complicated.

FullACK Thanks for your help. juh