Re: [NTG-context] Issues with RGB to CMYK conversion with color profiles
On Wed, Nov 21, 2018 at 3:02 PM Jan U. Hasecke 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 ___ 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 ___
Re: [NTG-context] Issues with RGB to CMYK conversion with color profiles
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 ___
Re: [NTG-context] Issues with RGB to CMYK conversion with color profiles
On Mon, Nov 19, 2018 at 10:57 AM Henning Hraban Ramm 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 ___ 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 ___
Re: [NTG-context] Issues with RGB to CMYK conversion with color profiles
Am 2018-11-18 um 19:26 schrieb Hans Hagen : > 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 ___
Re: [NTG-context] Issues with RGB to CMYK conversion with color profiles
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 ___
Re: [NTG-context] Issues with RGB to CMYK conversion with color profiles
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 ___
Re: [NTG-context] Issues with RGB to CMYK conversion with color profiles (was: Colormanagement)
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 ___
Re: [NTG-context] Issues with RGB to CMYK conversion with color profiles (was: Colormanagement)
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 >>> _
Re: [NTG-context] Issues with RGB to CMYK conversion with color profiles (was: Colormanagement)
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 > ___ > _
Re: [NTG-context] Issues with RGB to CMYK conversion with color profiles (was: Colormanagement)
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 ___
Re: [NTG-context] Issues with RGB to CMYK conversion with color profiles (was: Colormanagement)
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 > ___ > <> ___ 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 ___
Re: [NTG-context] Issues with RGB to CMYK conversion with color profiles (was: Colormanagement)
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 ___
Re: [NTG-context] Issues with RGB to CMYK conversion with color profiles
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 ___
[NTG-context] Issues with RGB to CMYK conversion with color profiles (was: Colormanagement)
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 ___