* Colormanagement
@ 2018-11-09 15:24 Jan U. Hasecke
2018-11-09 16:03 ` Colormanagement Hans Hagen
2018-11-09 16:20 ` Colormanagement luigi scarso
0 siblings, 2 replies; 21+ messages in thread
From: Jan U. Hasecke @ 2018-11-09 15:24 UTC (permalink / raw)
To: mailing list for ConTeXt users
Hi all,
I defined some colors with \definecolor like this:
\definecolor [myblue] [r=0.000, g=0.314, b=0.580, c=0.98, m=0.67,
y=0.03, k=0.12]
\startnotmode[print]
\setupcolors[cmyk=no,rgb=yes]
\stopnotmode
\startmode[print]
\setupcolors[cmyk=yes,rgb=no]
\setupbackend[
format=PDF/X-3:2003,
intent={ISO Coated v2 300\letterpercent\space (ECI)},
]
\stopmode
When I use "context" or "context --mode=print" everything works as expected.
But! I have SVG icons I want to use in the document. They contain the
above defined rgb colors.
When I use --mode=print I get different colors for the SVG icons.
So context converts the SVG files to PDFs but does not change the colors
accordingly to CMYK.
What are my options? Do I miss something?
1. Let the designer produce icons in pdf with the given cmyk colors.
2. Don't use cmyk colors at all.
In fact on my home printer the printed rgb colors look brighter than the
cmyk colors. This might change in the print shop when they print with
the right color profile, but it makes me nervous.
juh
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!
maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage : http://www.pragma-ade.nl / http://context.aanhet.net
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___________________________________________________________________________________
^ permalink raw reply [flat|nested] 21+ messages in thread* Re: Colormanagement 2018-11-09 15:24 Colormanagement Jan U. Hasecke @ 2018-11-09 16:03 ` Hans Hagen 2018-11-09 16:18 ` Colormanagement Tomas Hala 2018-11-09 16:20 ` Colormanagement luigi scarso 1 sibling, 1 reply; 21+ messages in thread From: Hans Hagen @ 2018-11-09 16:03 UTC (permalink / raw) To: mailing list for ConTeXt users, Jan U. Hasecke On 11/9/2018 4:24 PM, Jan U. Hasecke wrote: > So context converts the SVG files to PDFs but does not change the colors > accordingly to CMYK. i don't know if inkscape has a switch for conversion 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 ----------------------------------------------------------------- ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Colormanagement 2018-11-09 16:03 ` Colormanagement Hans Hagen @ 2018-11-09 16:18 ` Tomas Hala 2018-11-10 13:29 ` Colormanagement Jan U. Hasecke 0 siblings, 1 reply; 21+ messages in thread From: Tomas Hala @ 2018-11-09 16:18 UTC (permalink / raw) To: mailing list for ConTeXt users Hi, by default, really not. At http://wiki.inkscape.org/wiki/index.php/Color_management and http://wiki.inkscape.org/wiki/index.php/ExportPDFCMYK there some instructions how to convert files to CMYK, or how to install some extension, respectively. But I have not test these ways yet. Best wishes, Tomáš Fri, Nov 09, 2018 ve 05:03:43PM +0100 Hans Hagen napsal(a): # On 11/9/2018 4:24 PM, Jan U. Hasecke wrote: # # >So context converts the SVG files to PDFs but does not change the colors # >accordingly to CMYK. # i don't know if inkscape has a switch for conversion # # 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 # ----------------------------------------------------------------- # ___________________________________________________________________________________ # If your question is of interest to others as well, please add an entry to the Wiki! # # maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context # webpage : http://www.pragma-ade.nl / http://context.aanhet.net # archive : https://bitbucket.org/phg/context-mirror/commits/ # wiki : http://contextgarden.net # ___________________________________________________________________________________ Tomáš Hála -------------------------------------------------------------------- Mendelova univerzita, Provozně ekonomická fakulta, ústav informatiky Zemědělská 1, CZ-613 00 Brno, tel. +420 545 13 22 28 -------------------------------------------------------------------- http://akela.mendelu.cz/~thala ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Colormanagement 2018-11-09 16:18 ` Colormanagement Tomas Hala @ 2018-11-10 13:29 ` Jan U. Hasecke 0 siblings, 0 replies; 21+ messages in thread From: Jan U. Hasecke @ 2018-11-10 13:29 UTC (permalink / raw) To: mailing list for ConTeXt users Am 09.11.18 um 17:18 schrieb Tomas Hala: > Hi, > > by default, really not. > > At http://wiki.inkscape.org/wiki/index.php/Color_management > and http://wiki.inkscape.org/wiki/index.php/ExportPDFCMYK > there some instructions how to convert files to CMYK, > or how to install some extension, respectively. > But I have not test these ways yet. > These Python scripts does not work here. :-( But I could ask my designer to convert the RGB-SVG into CMYK-PDF. juh ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Colormanagement 2018-11-09 15:24 Colormanagement Jan U. Hasecke 2018-11-09 16:03 ` Colormanagement Hans Hagen @ 2018-11-09 16:20 ` luigi scarso 2018-11-10 13:34 ` Colormanagement Jan U. Hasecke 1 sibling, 1 reply; 21+ messages in thread From: luigi scarso @ 2018-11-09 16:20 UTC (permalink / raw) To: mailing list for ConTeXt users [-- Attachment #1.1: Type: text/plain, Size: 1411 bytes --] On Fri, Nov 9, 2018 at 4:24 PM Jan U. Hasecke <juh+ntg-context@mailbox.org> wrote: > Hi all, > > I defined some colors with \definecolor like this: > > \definecolor [myblue] [r=0.000, g=0.314, b=0.580, c=0.98, m=0.67, > y=0.03, k=0.12] > > \startnotmode[print] > \setupcolors[cmyk=no,rgb=yes] > \stopnotmode > > \startmode[print] > \setupcolors[cmyk=yes,rgb=no] > \setupbackend[ > format=PDF/X-3:2003, > intent={ISO Coated v2 300\letterpercent\space (ECI)}, > ] > \stopmode > > When I use "context" or "context --mode=print" everything works as > expected. > > But! I have SVG icons I want to use in the document. They contain the > above defined rgb colors. > > When I use --mode=print I get different colors for the SVG icons. > > So context converts the SVG files to PDFs but does not change the colors > accordingly to CMYK. > > What are my options? Do I miss something? > > 1. Let the designer produce icons in pdf with the given cmyk colors. > > 2. Don't use cmyk colors at all. > > In fact on my home printer the printed rgb colors look brighter than the > cmyk colors. This might change in the print shop when they print with > the right color profile, but it makes me nervous. > I think you should use the best colorspace (<something>rgb ) and let the print shop do its job -- of course this means that you have signed their sample (hard proof) of your project. Hraban ? -- luigi [-- Attachment #1.2: Type: text/html, Size: 2053 bytes --] [-- Attachment #2: Type: text/plain, Size: 492 bytes --] ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Colormanagement 2018-11-09 16:20 ` Colormanagement luigi scarso @ 2018-11-10 13:34 ` Jan U. Hasecke 2018-11-10 16:24 ` Colormanagement Hans Hagen 2018-11-12 8:02 ` Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) Jan U. Hasecke 0 siblings, 2 replies; 21+ messages in thread From: Jan U. Hasecke @ 2018-11-10 13:34 UTC (permalink / raw) To: ntg-context Am 09.11.18 um 17:20 schrieb luigi scarso: > I think you should use the best colorspace (<something>rgb ) > and let the print shop do its job -- of course this means that you have > signed their sample (hard proof) of your project. > I really tend to do this. I am currently exploring the color management system of ConTeXt together with a friend you is working as a color manager in print industry. And my first try was a failure. The cmyk values in the resulting pdf file (with color profile) differs from the values we calculated (using the same color profile in Gimp). But we have to investigate a bit further, so don't panic. Maybe I the fault was mine. Is there a test case tex file we could use to test the color management? juh ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Colormanagement 2018-11-10 13:34 ` Colormanagement Jan U. Hasecke @ 2018-11-10 16:24 ` Hans Hagen 2018-11-12 8:02 ` Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) Jan U. Hasecke 1 sibling, 0 replies; 21+ messages in thread From: Hans Hagen @ 2018-11-10 16:24 UTC (permalink / raw) To: mailing list for ConTeXt users, Jan U. Hasecke On 11/10/2018 2:34 PM, Jan U. Hasecke wrote: > Am 09.11.18 um 17:20 schrieb luigi scarso: >> I think you should use the best colorspace (<something>rgb ) >> and let the print shop do its job -- of course this means that you have >> signed their sample (hard proof) of your project. >> > > I really tend to do this. I am currently exploring the color management > system of ConTeXt together with a friend you is working as a color > manager in print industry. > > And my first try was a failure. The cmyk values in the resulting pdf > file (with color profile) differs from the values we calculated (using > the same color profile in Gimp). > > But we have to investigate a bit further, so don't panic. Maybe I the > fault was mine. > > Is there a test case tex file we could use to test the color management? there is no real 1-1 translation from rgb-cmyk .. in many programs that do that there is some additional magic (i remember that photoshop also applied the paper properties and that there was no roundtrip) this is where color profiles come in even viewers (like acrobat) can apply some magic so that the colors come out different from what you expect try this on screen and in print: \startMPpage path p ; p := fullcircle scaled 1cm ; fill p shifted (0cm,1cm) withcolor (1,1,0) ; fill p shifted (1cm,1cm) withcolor (0,0,1,0) ; fill p shifted (0cm,0cm) withcolor (1/2,1/2,0) ; fill p shifted (1cm,0cm) withcolor (0,0,1/2,0) ; \stopMPpage 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 ----------------------------------------------------------------- ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) 2018-11-10 13:34 ` Colormanagement Jan U. Hasecke 2018-11-10 16:24 ` Colormanagement Hans Hagen @ 2018-11-12 8:02 ` Jan U. Hasecke 2018-11-12 8:34 ` Issues with RGB to CMYK conversion with color profiles Hans Hagen 2018-11-14 10:39 ` Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) Jan U. Hasecke 1 sibling, 2 replies; 21+ messages in thread From: Jan U. Hasecke @ 2018-11-12 8:02 UTC (permalink / raw) To: ntg-context Hi all, with the following file I tested the color conversion of context. I get the same CMYK-values in the output pdf file using different color profiles. A friend of mine can test the color values of PDF with a special software. My guess: the profiles are not used during pdf generation. You can test this by commenting/uncommenting the other profile. I created the files with context --mode=print example.tex My context version is mtx-context | ConTeXt Process Management 1.02 mtx-context | current version: 2018.08.30 18:41 Is this the correct way of producing cmyk-pdfs? I am missing the declaration of the RGB color profile. When doing color management in Scribus I define two profiles: one for RGB and one for CMYK. AFAIK you need both to convert rgb to cmyk. Any hints? juh --- example.tex --- \definecolor [hs-logoblau] [r=0.000, g=0.314, b=0.580] \definecolor [hs-dunkelblau] [r=0.258, g=0.474, b=0.737] \definecolor [hs-hellblau] [r=0.6, g=0.737, b=0.858] \definecolor [hs-orange] [r=0.866, g=0.286, b=0.003] \startnotmode[print] \setupcolors[cmyk=no,rgb=yes] \stopnotmode \startmode[print] \setupcolors[cmyk=yes,rgb=no] \setupbackend[ format=PDF/X-1a:2003, % intent={ISO Coated v2 300\letterpercent\space (ECI)}, intent={SWOP2006_Coated3v2.icc}, ] \stopmode \setuppapersize [A4] [A4] \starttext \blackrule[width=3cm,height=1cm,depth=0pt,color=hs-orange] HS Orange r=0.866, g=0.286, b=0.003 \blank \blackrule[width=3cm,height=1cm,depth=0pt,color=hs-logoblau] HS Logoblau r=0.000, g=0.314, b=0.580 \blank \blackrule[width=3cm,height=1cm,depth=0pt,color=hs-dunkelblau] HS Dunkelblau r=0.258, g=0.474, b=0.737 \blank \blackrule[width=3cm,height=1cm,depth=0pt,color=hs-hellblau] HS Hellblau r=0.6, g=0.737, b=0.858 \stoptext ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Issues with RGB to CMYK conversion with color profiles 2018-11-12 8:02 ` Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) Jan U. Hasecke @ 2018-11-12 8:34 ` Hans Hagen 2018-11-14 10:39 ` Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) Jan U. Hasecke 1 sibling, 0 replies; 21+ messages in thread From: Hans Hagen @ 2018-11-12 8:34 UTC (permalink / raw) To: mailing list for ConTeXt users, Jan U. Hasecke On 11/12/2018 9:02 AM, Jan U. Hasecke wrote: > Hi all, > > with the following file I tested the color conversion of context. > > I get the same CMYK-values in the output pdf file using different color > profiles. A friend of mine can test the color values of PDF with a > special software. > > My guess: the profiles are not used during pdf generation. > You can test this by commenting/uncommenting the other profile. > > I created the files with > > context --mode=print example.tex > > My context version is > mtx-context | ConTeXt Process Management 1.02 > mtx-context | current version: 2018.08.30 18:41 > > > Is this the correct way of producing cmyk-pdfs? > > I am missing the declaration of the RGB color profile. When doing color > management in Scribus I define two profiles: one for RGB and one for > CMYK. AFAIK you need both to convert rgb to cmyk. > > Any hints? it's probably better to define hs-dunkelblau etc in cmyk color space then > juh > > --- example.tex --- > > \definecolor [hs-logoblau] [r=0.000, g=0.314, b=0.580] > \definecolor [hs-dunkelblau] [r=0.258, g=0.474, b=0.737] > \definecolor [hs-hellblau] [r=0.6, g=0.737, b=0.858] > \definecolor [hs-orange] [r=0.866, g=0.286, b=0.003] > > \startnotmode[print] > \setupcolors[cmyk=no,rgb=yes] > \stopnotmode > > \startmode[print] > \setupcolors[cmyk=yes,rgb=no] > \setupbackend[ > format=PDF/X-1a:2003, > % intent={ISO Coated v2 300\letterpercent\space (ECI)}, > intent={SWOP2006_Coated3v2.icc}, > ] > \stopmode > > \setuppapersize [A4] [A4] > > \starttext > > > > \blackrule[width=3cm,height=1cm,depth=0pt,color=hs-orange] HS Orange > r=0.866, g=0.286, b=0.003 > \blank > > \blackrule[width=3cm,height=1cm,depth=0pt,color=hs-logoblau] HS Logoblau > r=0.000, g=0.314, b=0.580 > \blank > > \blackrule[width=3cm,height=1cm,depth=0pt,color=hs-dunkelblau] HS > Dunkelblau r=0.258, g=0.474, b=0.737 > \blank > > \blackrule[width=3cm,height=1cm,depth=0pt,color=hs-hellblau] HS Hellblau > r=0.6, g=0.737, b=0.858 > > > \stoptext > > ___________________________________________________________________________________ > If your question is of interest to others as well, please add an entry to the Wiki! > > maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___________________________________________________________________________________ > -- ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl ----------------------------------------------------------------- ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) 2018-11-12 8:02 ` Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) Jan U. Hasecke 2018-11-12 8:34 ` Issues with RGB to CMYK conversion with color profiles Hans Hagen @ 2018-11-14 10:39 ` Jan U. Hasecke 2018-11-14 10:41 ` Jan U. Hasecke ` (2 more replies) 1 sibling, 3 replies; 21+ messages in thread From: Jan U. Hasecke @ 2018-11-14 10:39 UTC (permalink / raw) To: ntg-context Hi all, attached you find my colormanagement tests and I need your help to understand and debug the situation. I am testing together with a friend of mine, a professional colormanager, who does not know ConTeXt. There are several files in the archive: The differences in the files are the color definition and the color profile used. - rgb-xxx.tex – colors are defined with RGB values only. - rgb-cmyk-xxx.tex – colors are defined with RGB and CMYK values. The cmyk colors are derived from the rgb values using gimp and the color profiles sRGB/ISOCoated - cmyk-xxx.tex – colors are defined with CMYK values only. The xxx stand for two color profiles: iso-coated and swop. What I see is this: Colors in pdfs are the same no matter what color profile I choose. With rgb values and rgb/cmyk values I get the same colors in pdf (the wrong ones). With cmyk values only I get other colors in pdf. Next week my friend will test if these are the right ones. I have many questions: 1. Is colormanagement working in ConTeXt at all? 2. Is my code correct? 3. Why do pdfs with different color profiles show the same colors? 4. Why does ConTeXt not take the cmyk colors from \definecolor when there are rgb values as well? 5. Where can I define a coresponding rgb profile? In Scribus you have to define two profiles (eg. sRGB and ISOCoated) to make colormanagement work. TIA juh ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) 2018-11-14 10:39 ` Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) Jan U. Hasecke @ 2018-11-14 10:41 ` Jan U. Hasecke 2018-11-14 13:58 ` Peter Rolf 2018-11-14 15:51 ` Issues with RGB to CMYK conversion with color profiles Wolfgang Schuster 2 siblings, 0 replies; 21+ messages in thread From: Jan U. Hasecke @ 2018-11-14 10:41 UTC (permalink / raw) To: ntg-context [-- Attachment #1: Type: text/plain, Size: 2072 bytes --] I forgot the archive. :-( Am 14.11.18 um 11:39 schrieb Jan U. Hasecke: > Hi all, > > attached you find my colormanagement tests and I need your help to > understand and debug the situation. > > I am testing together with a friend of mine, a professional > colormanager, who does not know ConTeXt. > > > There are several files in the archive: > > The differences in the files are the color definition and the color > profile used. > > - rgb-xxx.tex – colors are defined with RGB values only. > > - rgb-cmyk-xxx.tex – colors are defined with RGB and CMYK values. > > The cmyk colors are derived from the rgb values using gimp and the > color profiles sRGB/ISOCoated > > - cmyk-xxx.tex – colors are defined with CMYK values only. > > The xxx stand for two color profiles: iso-coated and swop. > > What I see is this: > > Colors in pdfs are the same no matter what color profile I choose. > > With rgb values and rgb/cmyk values I get the same colors in pdf (the > wrong ones). > > With cmyk values only I get other colors in pdf. Next week my friend > will test if these are the right ones. > > I have many questions: > > 1. Is colormanagement working in ConTeXt at all? > 2. Is my code correct? > 3. Why do pdfs with different color profiles show the same colors? > 4. Why does ConTeXt not take the cmyk colors from \definecolor when > there are rgb values as well? > 5. Where can I define a coresponding rgb profile? In Scribus you have to > define two profiles (eg. sRGB and ISOCoated) to make colormanagement work. > > TIA > juh > ___________________________________________________________________________________ > If your question is of interest to others as well, please add an entry to the Wiki! > > maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___________________________________________________________________________________ > [-- Attachment #2: farbmanagement.zip --] [-- Type: application/zip, Size: 69827 bytes --] [-- Attachment #3: Type: text/plain, Size: 492 bytes --] ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) 2018-11-14 10:39 ` Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) Jan U. Hasecke 2018-11-14 10:41 ` Jan U. Hasecke @ 2018-11-14 13:58 ` Peter Rolf 2018-11-14 14:36 ` Jan U. Hasecke 2018-11-14 15:51 ` Issues with RGB to CMYK conversion with color profiles Wolfgang Schuster 2 siblings, 1 reply; 21+ messages in thread From: Peter Rolf @ 2018-11-14 13:58 UTC (permalink / raw) To: mailing list for ConTeXt users Hi Jan, I donno if things have changed (ConTeXt is a fast moving target), so take my answers with a grain of salt. (1) AFAIK there is no ACTIVE color management in ConTeXt in the sense that there is an automatic color conversion from one profiled(!) colorspace into another profiled color space. This means that all given colors (objects) have to be in the correct (profiled) color space already! Objects with embedded color profiles (e.g. a PDF bitmap graphic with icc profile) will use those. Objects without a profile will use the corresponding "default" color space profiles. These default color space profiles can be defined via "profile" in \setupbackend. This way every color in the PDF is defined properly. (2) I think so. Can't test, because my Windows 10 is beyond repair after three "upgrades" and Acrobat is not working properly anymore. (3) Judging from the size of the final PDF, the icc profile is not embedded. The profiles have to be installed in "the right place" (this includes ConTeXt but also the PDF viewer software). See "ICC profiles" section at https://wiki.contextgarden.net/PDFX (5) see (1) and (3) Hope this helps, Peter Am 2018-11-14 um 11:39 schrieb Jan U. Hasecke: > Hi all, > > attached you find my colormanagement tests and I need your help to > understand and debug the situation. > > I am testing together with a friend of mine, a professional > colormanager, who does not know ConTeXt. > > > There are several files in the archive: > > The differences in the files are the color definition and the color > profile used. > > - rgb-xxx.tex – colors are defined with RGB values only. > > - rgb-cmyk-xxx.tex – colors are defined with RGB and CMYK values. > > The cmyk colors are derived from the rgb values using gimp and the > color profiles sRGB/ISOCoated > > - cmyk-xxx.tex – colors are defined with CMYK values only. > > The xxx stand for two color profiles: iso-coated and swop. > > What I see is this: > > Colors in pdfs are the same no matter what color profile I choose. > > With rgb values and rgb/cmyk values I get the same colors in pdf (the > wrong ones). > > With cmyk values only I get other colors in pdf. Next week my friend > will test if these are the right ones. > > I have many questions: > > 1. Is colormanagement working in ConTeXt at all? > 2. Is my code correct? > 3. Why do pdfs with different color profiles show the same colors? > 4. Why does ConTeXt not take the cmyk colors from \definecolor when > there are rgb values as well? > 5. Where can I define a coresponding rgb profile? In Scribus you have to > define two profiles (eg. sRGB and ISOCoated) to make colormanagement work. > > TIA > juh > ___________________________________________________________________________________ > If your question is of interest to others as well, please add an entry to the Wiki! > > maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___________________________________________________________________________________ > ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) 2018-11-14 13:58 ` Peter Rolf @ 2018-11-14 14:36 ` Jan U. Hasecke 2018-11-14 15:04 ` Peter Rolf 0 siblings, 1 reply; 21+ messages in thread From: Jan U. Hasecke @ 2018-11-14 14:36 UTC (permalink / raw) To: ntg-context Thanks a lot, Peter. Am 14.11.18 um 14:58 schrieb Peter Rolf: > Hi Jan, > > I donno if things have changed (ConTeXt is a fast moving target), so > take my answers with a grain of salt. > > (1) > AFAIK there is no ACTIVE color management in ConTeXt in the sense that > there is an automatic color conversion from one profiled(!) colorspace > into another profiled color space. This means that all given colors > (objects) have to be in the correct (profiled) color space already! > > Objects with embedded color profiles (e.g. a PDF bitmap graphic with icc > profile) will use those. Objects without a profile will use the > corresponding "default" color space profiles. These default color space > profiles can be defined via "profile" in \setupbackend. > This way every color in the PDF is defined properly. This would clarify some of the issues. When I define rgb colors AND use not-print-modus I get the right rgb colors in the pdf. When I define cmyk colors AND use print modus I get colors that might be correct (tested next week) But obviously it is not possible to define both color spaces in \definecolor because I don't get the same colors in the pdf as with the cmyk-only defined file. Maybe I misunderstood this, I've got a hint here, that I could define rgb and cmyk in the same \definecolor and choose the right color space in \setupcolors. The correct method of defining rgb AND cmyk in the same file would be to put the definecolor command inside a startstopmode-environment. Can someone confirm this? > > (2) > > I think so. Can't test, because my Windows 10 is beyond repair after > three "upgrades" and Acrobat is not working properly anymore. > > (3) > > Judging from the size of the final PDF, the icc profile is not embedded. > The profiles have to be installed in "the right place" (this includes > ConTeXt but also the PDF viewer software). > > See "ICC profiles" section at > > https://wiki.contextgarden.net/PDFX > With --mode=print (which uses the color profiles) the pdf get bigger. >10.000 compared to 8.000 without the mode. So I would guess that they are included. I hope I get this sorted out, because I want to print a series of folders and other print products with ConTeXt in the near future. juh > (5) see (1) and (3) > > > > Hope this helps, > > > Peter > > > Am 2018-11-14 um 11:39 schrieb Jan U. Hasecke: >> Hi all, >> >> attached you find my colormanagement tests and I need your help to >> understand and debug the situation. >> >> I am testing together with a friend of mine, a professional >> colormanager, who does not know ConTeXt. >> >> >> There are several files in the archive: >> >> The differences in the files are the color definition and the color >> profile used. >> >> - rgb-xxx.tex – colors are defined with RGB values only. >> >> - rgb-cmyk-xxx.tex – colors are defined with RGB and CMYK values. >> >> The cmyk colors are derived from the rgb values using gimp and the >> color profiles sRGB/ISOCoated >> >> - cmyk-xxx.tex – colors are defined with CMYK values only. >> >> The xxx stand for two color profiles: iso-coated and swop. >> >> What I see is this: >> >> Colors in pdfs are the same no matter what color profile I choose. >> >> With rgb values and rgb/cmyk values I get the same colors in pdf (the >> wrong ones). >> >> With cmyk values only I get other colors in pdf. Next week my friend >> will test if these are the right ones. >> >> I have many questions: >> >> 1. Is colormanagement working in ConTeXt at all? >> 2. Is my code correct? >> 3. Why do pdfs with different color profiles show the same colors? >> 4. Why does ConTeXt not take the cmyk colors from \definecolor when >> there are rgb values as well? >> 5. Where can I define a coresponding rgb profile? In Scribus you have to >> define two profiles (eg. sRGB and ISOCoated) to make colormanagement work. >> >> TIA >> juh >> ___________________________________________________________________________________ >> If your question is of interest to others as well, please add an entry to the Wiki! >> >> maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context >> webpage : http://www.pragma-ade.nl / http://context.aanhet.net >> archive : https://bitbucket.org/phg/context-mirror/commits/ >> wiki : http://contextgarden.net >> ___________________________________________________________________________________ >> > > ___________________________________________________________________________________ > If your question is of interest to others as well, please add an entry to the Wiki! > > maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___________________________________________________________________________________ > ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) 2018-11-14 14:36 ` Jan U. Hasecke @ 2018-11-14 15:04 ` Peter Rolf 2018-11-14 15:31 ` Jan U. Hasecke 0 siblings, 1 reply; 21+ messages in thread From: Peter Rolf @ 2018-11-14 15:04 UTC (permalink / raw) To: ntg-context Am 2018-11-14 um 15:36 schrieb Jan U. Hasecke: > Thanks a lot, Peter. > > Am 14.11.18 um 14:58 schrieb Peter Rolf: >> Hi Jan, >> >> I donno if things have changed (ConTeXt is a fast moving target), so >> take my answers with a grain of salt. >> >> (1) >> AFAIK there is no ACTIVE color management in ConTeXt in the sense that >> there is an automatic color conversion from one profiled(!) colorspace >> into another profiled color space. This means that all given colors >> (objects) have to be in the correct (profiled) color space already! >> >> Objects with embedded color profiles (e.g. a PDF bitmap graphic with icc >> profile) will use those. Objects without a profile will use the >> corresponding "default" color space profiles. These default color space >> profiles can be defined via "profile" in \setupbackend. >> This way every color in the PDF is defined properly. > > This would clarify some of the issues. > > When I define rgb colors AND use not-print-modus I get the right rgb > colors in the pdf. > > When I define cmyk colors AND use print modus I get colors that might be > correct (tested next week) > > But obviously it is not possible to define both color spaces in > \definecolor because I don't get the same colors in the pdf as with the > cmyk-only defined file. > > Maybe I misunderstood this, I've got a hint here, that I could define > rgb and cmyk in the same \definecolor and choose the right color space > in \setupcolors. > > The correct method of defining rgb AND cmyk in the same file would be to > put the definecolor command inside a startstopmode-environment. > > Can someone confirm this? > Should work (the other part is invisible for ConTeXt). >> >> (2) >> >> I think so. Can't test, because my Windows 10 is beyond repair after >> three "upgrades" and Acrobat is not working properly anymore. >> >> (3) >> >> Judging from the size of the final PDF, the icc profile is not embedded. >> The profiles have to be installed in "the right place" (this includes >> ConTeXt but also the PDF viewer software). >> >> See "ICC profiles" section at >> >> https://wiki.contextgarden.net/PDFX >> > > With --mode=print (which uses the color profiles) the pdf get bigger. >> 10.000 compared to 8.000 without the mode. So I would guess that they > are included. > Mh, the file size of "ISOcoated_v2_300_eci.icc" is around 1.7MB. I highly doubt that ConTeXt can compress it into a 10KB PDF. But I'm not so sure if PDF/X-3 needs embedding (there was an exception). Never used it (only PDF/X-4p) and I can't remember the specifications (all those stuff was added over 8 years ago). I just assume you have installed the icc profiles properly (needs a manual installation!) :D > I hope I get this sorted out, because I want to print a series of > folders and other print products with ConTeXt in the near future. > > juh > >> (5) see (1) and (3) >> >> >> >> Hope this helps, >> >> >> Peter >> >> >> Am 2018-11-14 um 11:39 schrieb Jan U. Hasecke: >>> Hi all, >>> >>> attached you find my colormanagement tests and I need your help to >>> understand and debug the situation. >>> >>> I am testing together with a friend of mine, a professional >>> colormanager, who does not know ConTeXt. >>> >>> >>> There are several files in the archive: >>> >>> The differences in the files are the color definition and the color >>> profile used. >>> >>> - rgb-xxx.tex – colors are defined with RGB values only. >>> >>> - rgb-cmyk-xxx.tex – colors are defined with RGB and CMYK values. >>> >>> The cmyk colors are derived from the rgb values using gimp and the >>> color profiles sRGB/ISOCoated >>> >>> - cmyk-xxx.tex – colors are defined with CMYK values only. >>> >>> The xxx stand for two color profiles: iso-coated and swop. >>> >>> What I see is this: >>> >>> Colors in pdfs are the same no matter what color profile I choose. >>> >>> With rgb values and rgb/cmyk values I get the same colors in pdf (the >>> wrong ones). >>> >>> With cmyk values only I get other colors in pdf. Next week my friend >>> will test if these are the right ones. >>> >>> I have many questions: >>> >>> 1. Is colormanagement working in ConTeXt at all? >>> 2. Is my code correct? >>> 3. Why do pdfs with different color profiles show the same colors? >>> 4. Why does ConTeXt not take the cmyk colors from \definecolor when >>> there are rgb values as well? >>> 5. Where can I define a coresponding rgb profile? In Scribus you have to >>> define two profiles (eg. sRGB and ISOCoated) to make colormanagement work. >>> >>> TIA >>> juh >>> ___________________________________________________________________________________ >>> If your question is of interest to others as well, please add an entry to the Wiki! >>> >>> maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context >>> webpage : http://www.pragma-ade.nl / http://context.aanhet.net >>> archive : https://bitbucket.org/phg/context-mirror/commits/ >>> wiki : http://contextgarden.net >>> ___________________________________________________________________________________ >>> >> >> ___________________________________________________________________________________ >> If your question is of interest to others as well, please add an entry to the Wiki! >> >> maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context >> webpage : http://www.pragma-ade.nl / http://context.aanhet.net >> archive : https://bitbucket.org/phg/context-mirror/commits/ >> wiki : http://contextgarden.net >> ___________________________________________________________________________________ >> > > ___________________________________________________________________________________ > If your question is of interest to others as well, please add an entry to the Wiki! > > maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___________________________________________________________________________________ > ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) 2018-11-14 15:04 ` Peter Rolf @ 2018-11-14 15:31 ` Jan U. Hasecke 0 siblings, 0 replies; 21+ messages in thread From: Jan U. Hasecke @ 2018-11-14 15:31 UTC (permalink / raw) To: ntg-context Am 14.11.18 um 16:04 schrieb Peter Rolf: > Mh, the file size of "ISOcoated_v2_300_eci.icc" is around 1.7MB. I > highly doubt that ConTeXt can compress it into a 10KB PDF. > > But I'm not so sure if PDF/X-3 needs embedding (there was an exception). > Never used it (only PDF/X-4p) and I can't remember the specifications > (all those stuff was added over 8 years ago). > > I just assume you have installed the icc profiles properly (needs a > manual installation!) :D There are some profiles in the context installation. At least something was found: backend > profiles > profile specification 'ISOcoated_v2_300_eci.icc' loaded from '/home/juh/context/tex/texmf-context/colors/icc/context/colorprofiles.xml' backend > profiles > omitting reference to profile for intent 'ISO Coated v2 300% (ECI)' But, yes the size is too small to have the whole profile incorporated. juh ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Issues with RGB to CMYK conversion with color profiles 2018-11-14 10:39 ` Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) Jan U. Hasecke 2018-11-14 10:41 ` Jan U. Hasecke 2018-11-14 13:58 ` Peter Rolf @ 2018-11-14 15:51 ` Wolfgang Schuster 2018-11-18 18:26 ` Hans Hagen 2 siblings, 1 reply; 21+ messages in thread From: Wolfgang Schuster @ 2018-11-14 15:51 UTC (permalink / raw) To: mailing list for ConTeXt users, Jan U. Hasecke Jan U. Hasecke schrieb am 14.11.18 um 11:39: > Hi all, > > attached you find my colormanagement tests and I need your help to > understand and debug the situation. > > I am testing together with a friend of mine, a professional > colormanager, who does not know ConTeXt. Even without a color profile the results from the normal conversion of colors from cmyk to rgb can result in differences between ConTeXt and Gimp because both use different formulas. This is the formula from ConTeXt (attr-col.lua) r = 1.0 - math.min(1.0,c+k) g = 1.0 - math.min(1.0,m+k) b = 1.0 - math.min(1.0,y+k) and this is the one from Gimp (https://gitlab.gnome.org/GNOME/gimp/blob/master/libgimpcolor/gimpcolorspace.c) r = 1.0 - math.min(1.0,c*(1.0-k)+k) g = 1.0 - math.min(1.0,m*(1.0-k)+k) b = 1.0 - math.min(1.0,y*(1.0-k)+k) Wolfgang ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Issues with RGB to CMYK conversion with color profiles 2018-11-14 15:51 ` Issues with RGB to CMYK conversion with color profiles Wolfgang Schuster @ 2018-11-18 18:26 ` Hans Hagen 2018-11-19 9:56 ` Henning Hraban Ramm 0 siblings, 1 reply; 21+ messages in thread From: Hans Hagen @ 2018-11-18 18:26 UTC (permalink / raw) To: mailing list for ConTeXt users, Wolfgang Schuster, Jan U. Hasecke On 11/14/2018 4:51 PM, Wolfgang Schuster wrote: > Jan U. Hasecke schrieb am 14.11.18 um 11:39: >> Hi all, >> >> attached you find my colormanagement tests and I need your help to >> understand and debug the situation. >> >> I am testing together with a friend of mine, a professional >> colormanager, who does not know ConTeXt. > > Even without a color profile the results from the normal conversion of > colors from cmyk to rgb > can result in differences between ConTeXt and Gimp because both use > different formulas. > > This is the formula from ConTeXt (attr-col.lua) > > r = 1.0 - math.min(1.0,c+k) > g = 1.0 - math.min(1.0,m+k) > b = 1.0 - math.min(1.0,y+k) > > and this is the one from Gimp > (https://gitlab.gnome.org/GNOME/gimp/blob/master/libgimpcolor/gimpcolorspace.c) > > > r = 1.0 - math.min(1.0,c*(1.0-k)+k) > g = 1.0 - math.min(1.0,m*(1.0-k)+k) > b = 1.0 - math.min(1.0,y*(1.0-k)+k) Are there more variants? Do we need to support variants? 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 ----------------------------------------------------------------- ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Issues with RGB to CMYK conversion with color profiles 2018-11-18 18:26 ` Hans Hagen @ 2018-11-19 9:56 ` Henning Hraban Ramm 2018-11-19 10:14 ` luigi scarso 0 siblings, 1 reply; 21+ messages in thread From: Henning Hraban Ramm @ 2018-11-19 9:56 UTC (permalink / raw) To: mailing list for ConTeXt users Am 2018-11-18 um 19:26 schrieb Hans Hagen <j.hagen@xs4all.nl>: > On 11/14/2018 4:51 PM, Wolfgang Schuster wrote: >> Jan U. Hasecke schrieb am 14.11.18 um 11:39: >>> Hi all, >>> >>> attached you find my colormanagement tests and I need your help to >>> understand and debug the situation. >>> >>> I am testing together with a friend of mine, a professional >>> colormanager, who does not know ConTeXt. >> Even without a color profile the results from the normal conversion of colors from cmyk to rgb >> can result in differences between ConTeXt and Gimp because both use different formulas. >> This is the formula from ConTeXt (attr-col.lua) >> r = 1.0 - math.min(1.0,c+k) >> g = 1.0 - math.min(1.0,m+k) >> b = 1.0 - math.min(1.0,y+k) >> and this is the one from Gimp (https://gitlab.gnome.org/GNOME/gimp/blob/master/libgimpcolor/gimpcolorspace.c) r = 1.0 - math.min(1.0,c*(1.0-k)+k) >> g = 1.0 - math.min(1.0,m*(1.0-k)+k) >> b = 1.0 - math.min(1.0,y*(1.0-k)+k) > Are there more variants? Do we need to support variants? Oh my, color separation is a science of its own, but not an exact science... Any really usable color conversion algorithm uses color profiles. It would make sense to outsource color calculations to a color management library like LittleCMS. Greetlings, Hraban --- https://www.fiee.net http://wiki.contextgarden.net https://www.dreiviertelhaus.de GPG Key ID 1C9B22FD ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Issues with RGB to CMYK conversion with color profiles 2018-11-19 9:56 ` Henning Hraban Ramm @ 2018-11-19 10:14 ` luigi scarso 2018-11-21 14:01 ` Jan U. Hasecke 0 siblings, 1 reply; 21+ messages in thread From: luigi scarso @ 2018-11-19 10:14 UTC (permalink / raw) To: ntg-context [-- Attachment #1.1: Type: text/plain, Size: 282 bytes --] On Mon, Nov 19, 2018 at 10:57 AM Henning Hraban Ramm <texml@fiee.net> wrote: > > It would make sense to outsource color calculations to a color management > library like LittleCMS. > > yes. Perhaps this is still useful https://www.tug.org/TUGboat/tb31-3/tb99scarso.pdf -- luigi [-- Attachment #1.2: Type: text/html, Size: 920 bytes --] [-- Attachment #2: Type: text/plain, Size: 492 bytes --] ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Issues with RGB to CMYK conversion with color profiles 2018-11-19 10:14 ` luigi scarso @ 2018-11-21 14:01 ` Jan U. Hasecke 2018-11-21 14:42 ` luigi scarso 0 siblings, 1 reply; 21+ messages in thread From: Jan U. Hasecke @ 2018-11-21 14:01 UTC (permalink / raw) To: ntg-context Am 19.11.18 um 11:14 schrieb luigi scarso: > Perhaps this is still useful > https://www.tug.org/TUGboat/tb31-3/tb99scarso.pdf Thanks a lot for the hint. I don't understand the equations but at least I found transicc to calculate color conversions. What precision is useful in the wild? I now use three digits after the decimal point, eg.: \definecolor [hs-logoblau] [c=0.976, m=0.665, y=0.028, k=0.116] juh ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: Issues with RGB to CMYK conversion with color profiles 2018-11-21 14:01 ` Jan U. Hasecke @ 2018-11-21 14:42 ` luigi scarso 0 siblings, 0 replies; 21+ messages in thread From: luigi scarso @ 2018-11-21 14:42 UTC (permalink / raw) To: mailing list for ConTeXt users [-- Attachment #1.1: Type: text/plain, Size: 1112 bytes --] On Wed, Nov 21, 2018 at 3:02 PM Jan U. Hasecke <juh+ntg-context@mailbox.org> wrote: > Am 19.11.18 um 11:14 schrieb luigi scarso: > > > Perhaps this is still useful > > https://www.tug.org/TUGboat/tb31-3/tb99scarso.pdf > > Thanks a lot for the hint. > > I don't understand the equations but at least I found transicc to > calculate color conversions. > > What precision is useful in the wild? > > I now use three digits after the decimal point, eg.: > > \definecolor [hs-logoblau] [c=0.976, m=0.665, y=0.028, k=0.116] > > It's safe to specify a color as 8bit per channel rgb, or in percent. i.e. see for example https://en.wikipedia.org/wiki/List_of_colors:_A%E2%80%93F (more on https://en.wikipedia.org/wiki/Lists_of_colors ) 16bit per channel rgb are also possible, but old RIP can have problems (for example https://www.pantone.com/color-finder/#/pick?pantoneBook=pantoneSolidCoatedV3M2 shows rgb 8bit per channel and CMYK 0 to 100) Btw: be careful of the checker shadow illusion https://en.wikipedia.org/wiki/Optical_illusion colors not always look as they are expressed in numeric form. -- luigi [-- Attachment #1.2: Type: text/html, Size: 2151 bytes --] [-- Attachment #2: Type: text/plain, Size: 492 bytes --] ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________ ^ permalink raw reply [flat|nested] 21+ messages in thread
end of thread, other threads:[~2018-11-21 14:42 UTC | newest] Thread overview: 21+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2018-11-09 15:24 Colormanagement Jan U. Hasecke 2018-11-09 16:03 ` Colormanagement Hans Hagen 2018-11-09 16:18 ` Colormanagement Tomas Hala 2018-11-10 13:29 ` Colormanagement Jan U. Hasecke 2018-11-09 16:20 ` Colormanagement luigi scarso 2018-11-10 13:34 ` Colormanagement Jan U. Hasecke 2018-11-10 16:24 ` Colormanagement Hans Hagen 2018-11-12 8:02 ` Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) Jan U. Hasecke 2018-11-12 8:34 ` Issues with RGB to CMYK conversion with color profiles Hans Hagen 2018-11-14 10:39 ` Issues with RGB to CMYK conversion with color profiles (was: Colormanagement) Jan U. Hasecke 2018-11-14 10:41 ` Jan U. Hasecke 2018-11-14 13:58 ` Peter Rolf 2018-11-14 14:36 ` Jan U. Hasecke 2018-11-14 15:04 ` Peter Rolf 2018-11-14 15:31 ` Jan U. Hasecke 2018-11-14 15:51 ` Issues with RGB to CMYK conversion with color profiles Wolfgang Schuster 2018-11-18 18:26 ` Hans Hagen 2018-11-19 9:56 ` Henning Hraban Ramm 2018-11-19 10:14 ` luigi scarso 2018-11-21 14:01 ` Jan U. Hasecke 2018-11-21 14:42 ` luigi scarso
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