Comments on: 100% Cyan in CMYK is NOT rgb(0,255,255)!! http://lea.verou.me/2009/03/100-cyan-in-cmyk-is-not-rgb0255255/ Life at the bleeding edge (of web standards) Fri, 10 Feb 2012 07:25:15 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: curious http://lea.verou.me/2009/03/100-cyan-in-cmyk-is-not-rgb0255255/#comment-2933 curious Mon, 18 Apr 2011 00:50:00 +0000 http://leaverou.me/?p=259#comment-2933 i just did a google search for "rgb equivalent of 100c 100m 100y" ---and after reading this interesting post of yours--- it seems there may be one small and somewhat simple consideration that's getting overlooked in this discussion. it may help clarify for some. ---the Keep It Simple approach is often applicable even when dealing with color formula --- bottom line being the intended end-use of the color formula you are creating. Any color-critical task is always going to be more clear-cut and you will pull-out-less-hair if you keep in mind the question: is my intended end-use of the color going to be ON-SCREEN or ON-PAPER[and/or other print substrate(s)]. Trying to find some kind of utopian hybrid color or color space between RGB and CMYK is always going to be more likely to cause frustration. i suppose my rant/response stems from my search which developed from trying exercise some very basic print-color-control when using a free graphics progam such as GIMP (which does not create CMYK files) when i don't have my obvious favorite Photoshop, but the files created are going to be printed with CMYK inks. Well, actually in my case I simply want to omit the use of any black ink by replacing all values in the image that would require black ink to be created with the RGB numbers/percentages that equate to a dark-grey virtually black that can be created with c100, m100, y100. So my end-use is somewhat strange (RGB for printing), while many folks are probably trying to to take CMYK-to-RGB for the sake of accurate on-screen display. Photoshop is the right tool for this little task I'm trying and it makes it really simple, but maybe i just enjoy the challenge of trying to figure out if some simple things like this can be done with the free program(s). i just did a google search for “rgb equivalent of 100c 100m 100y”
—and after reading this interesting post of yours—
it seems there may be one small and somewhat simple consideration that’s getting overlooked in this discussion. it may help clarify for some. —the Keep It Simple approach is often applicable even when dealing with color formula — bottom line being the intended end-use of the color formula you are creating. Any color-critical task is always going to be more clear-cut and you will pull-out-less-hair if you keep in mind the question: is my intended end-use of the color going to be ON-SCREEN or ON-PAPER[and/or other print substrate(s)]. Trying to find some kind of utopian hybrid color or color space between RGB and CMYK is always going to be more likely to cause frustration. i suppose my rant/response stems from my search which developed from trying exercise some very basic print-color-control when using a free graphics progam such as GIMP (which does not create CMYK files) when i don’t have my obvious favorite Photoshop, but the files created are going to be printed with CMYK inks. Well, actually in my case I simply want to omit the use of any black ink by replacing all values in the image that would require black ink to be created with the RGB numbers/percentages that equate to a dark-grey virtually black that can be created with c100, m100, y100. So my end-use is somewhat strange (RGB for printing), while many folks are probably trying to to take CMYK-to-RGB for the sake of accurate on-screen display. Photoshop is the right tool for this little task I’m trying and it makes it really simple, but maybe i just enjoy the challenge of trying to figure out if some simple things like this can be done with the free program(s).

]]> By: Lea Verou http://lea.verou.me/2009/03/100-cyan-in-cmyk-is-not-rgb0255255/#comment-1549 Lea Verou Mon, 29 Nov 2010 09:52:09 +0000 http://leaverou.me/?p=259#comment-1549 That's exactly the point: That they look radically different. There are colors within the RGB spectrum that look much closer to CMYK cyan. Also, there's no rgb(0, 256, 256), the components go up to 255 (0-255, 1 byte each) That’s exactly the point: That they look radically different. There are colors within the RGB spectrum that look much closer to CMYK cyan.
Also, there’s no rgb(0, 256, 256), the components go up to 255 (0-255, 1 byte each)

]]> By: mathart63 http://lea.verou.me/2009/03/100-cyan-in-cmyk-is-not-rgb0255255/#comment-1544 mathart63 Sun, 28 Nov 2010 04:53:18 +0000 http://leaverou.me/?p=259#comment-1544 Just tried printing rgb(0,256,256) from PE on an HP inkjet printer and darned if it didn't look like pure cyan! (Note that the appearance of rgb(0,256,256) on the screen and the cyan output by the printer were radically different) Just tried printing rgb(0,256,256) from PE on an HP inkjet printer and darned if it didn’t look like pure cyan! (Note that the appearance of rgb(0,256,256) on the screen and the cyan output by the printer were radically different)

]]> By: razrwolf http://lea.verou.me/2009/03/100-cyan-in-cmyk-is-not-rgb0255255/#comment-1391 razrwolf Mon, 20 Sep 2010 12:46:42 +0000 http://leaverou.me/?p=259#comment-1391 @abelthorne, I know this may be a year late, but littleCMS is what scribus uses for its color management this may help other people who went through the scribus source looking for how to do color conversion(me :D) @abelthorne, I know this may be a year late, but littleCMS is what scribus uses for its color management
this may help other people who went through the scribus source looking for how to do color conversion(me :D )

]]> By: abelthorne http://lea.verou.me/2009/03/100-cyan-in-cmyk-is-not-rgb0255255/#comment-450 abelthorne Thu, 18 Jun 2009 21:12:30 +0000 http://leaverou.me/?p=259#comment-450 I'm currently trying to figure out how to properly convert CMYK to RGB values. So far, I haven't been able to find a correct algorithm (for the reasons you describe). One possibility I'm considering would be to understand how Scribus (free / opensource DTP software) does its conversions with CMYK RGB, as it does them quite well. Problem: the source code is really big and I'm quite lost in it. Maybe asking for help on the Scribus mailing list would provide basic explanations for a working algorithm. I’m currently trying to figure out how to properly convert CMYK to RGB values. So far, I haven’t been able to find a correct algorithm (for the reasons you describe).
One possibility I’m considering would be to understand how Scribus (free / opensource DTP software) does its conversions with CMYK RGB, as it does them quite well. Problem: the source code is really big and I’m quite lost in it. Maybe asking for help on the Scribus mailing list would provide basic explanations for a working algorithm.

]]> By: Marc Palau http://lea.verou.me/2009/03/100-cyan-in-cmyk-is-not-rgb0255255/#comment-409 Marc Palau Mon, 25 May 2009 23:14:38 +0000 http://leaverou.me/?p=259#comment-409 After reading so much, I understand that the main problem is that adobe koler uses diferent CMYK conversion tables (ICC). The correct way to understand this is knowing what ICC profile are you using in Photoshop (or Adobe software). If you use the sRGB IEC61966-2.1 profile then rgb(0,255,255) will be cmyk(57,0,13,0). Now, if you try it with a different profile for example ARRIFLEX D-20 Daylight Log (by Adobe), rgb(0,255,255) will be cmyk(100,0,0,0). The main problem that you will find at this point, is that each user uses his own color profile, this represents that each navigator are using its own configuration, then a perfect translation is not possible at moment. Maybe knowing the current color profile you can use the tables to made a 'perfect' translation of the colors, or maybe using Flash Player there is a hack to know any information about the color profile. For my project, I think I don't will use the CMYK translation, you have reason with the target of the applications and I think this only can got me problems. reggards and cya! Marc After reading so much, I understand that the main problem is that adobe koler uses diferent CMYK conversion tables (ICC).

The correct way to understand this is knowing what ICC profile are you using in Photoshop (or Adobe software). If you use the sRGB IEC61966-2.1 profile then rgb(0,255,255) will be cmyk(57,0,13,0). Now, if you try it with a different profile for example ARRIFLEX D-20 Daylight Log (by Adobe), rgb(0,255,255) will be cmyk(100,0,0,0).

The main problem that you will find at this point, is that each user uses his own color profile, this represents that each navigator are using its own configuration, then a perfect translation is not possible at moment. Maybe knowing the current color profile you can use the tables to made a ‘perfect’ translation of the colors, or maybe using Flash Player there is a hack to know any information about the color profile.

For my project, I think I don’t will use the CMYK translation, you have reason with the target of the applications and I think this only can got me problems.

reggards and cya!
Marc

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