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Thread: CMYK: which swatch?

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    keith1 is offline Member
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    Default CMYK: which swatch?

    Greetings,

    I'm surprised I don't see an existing thread for this.
    Does anyone know, as of this time - October 2012 - which spot to CMYK swatch is the most up to date and reliable?

    Here's what I have for Pantone 187 red (coated):

    My colour bridge swatch: 5; 100; 71; 22 (swatch is about 4 years old)
    Photoshop CS5 is the same: 5; 100; 71; 22
    Pantone Colour Manager software: 7; 100; 82; 26
    InDesign CS3 (which is the version I still usually use): 0; 100; 79; 20

    This conversion for 187 is reasonably close enough that any one of them will do the trick (unless one has an absolute dick for a customer; but none of us do, right?). However I'm sure I've seen other colours that differ much greater. Granted my stuff might not be the latest editions etc. Does someone know which is? The colour conversions seem to differ every time a new swatch comes out.

    Thanks,
    Keith

  2. #2
    Stephen Marsh is offline Senior Member
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    Hard wired CMYK numbers are problematic to work with.

    Best results are gained with a Pantone L*a*b* based library, converting to profile absolute colorimetric intent (or relative colorimetric), with the destination profile being the profile that describes your final print conditions.

    I believe that Pantone+ Solid Coated (lab) is the latest library.

    The L*a*b* values for Pantone+ 187 C are: L37.7 a56.5 b29.9
    In Photoshop CS 5 these rounded values are: L38 a57 b29

    If you really must use the hard wired Bridge values for coated, then from CS5 the solid Process values are: 0c 100m 79y 20k (whatever this press condition is, probably close to F39 or GRACoL C1).


    Stephen Marsh

  3. #3
    keith1 is offline Member
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    Hi Stephen,

    Final print conditions are CMYK. I often work with spot colours and convert using the print dialog. However different versions of software or different colour swatch books will give you different conversion values.

    For example several years ago I was signing off on a proof and a colour was way off. We compared the CMYK values I had used. I forget where they came from. Likely Adobe software conversion (spot to CMYK). The printer had the version of colour bridge swatch which had just come out. The values (numbers) were way different!

    I suppose part of my point is that with each update, Pantone appears to say; ooops! we kind of screwed up the conversion values of x number of colours. Try these instead. hah,hah.

    I know there's lots of variables. Not the least of which is what happens on the press. But a good starting point would be nice. Thus my question. Which is generally more accurate over the greater number of colours? I currently have a choice between my Bridge Swatches; my Adobe software and my Pantone Colour Manager Software. They can all be different. WTF!
    I have spot colour books too but they don't show conversion to CMYK values.

    Almost seems like a plot to keep people investing in swatch books . . .like the new colours that keep appearing with each version.

    Keith

    PS/ The process values for 187 you list at the bottom of your post are different from others that are available, such as Colour Manager. And this is my point. Which does one use? I only used PMS 187 as an example because it was in front of me. Other colours can differ a lot more from one guide to another.
    Last edited by keith1; 10-19-2012 at 12:16 AM.

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    Stephen Marsh is offline Senior Member
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    To know what CMYK values to use, one has to know the print condition! This is why working from device independent values to a known output profile will provide better results than unknown hard wired CMYK values.

    This is the problem with hard wired Pantone Process values, they don't mean much unless you are printing to that condition, the numbers are device dependent and the device is unknown.

    I just checked the Pantone Solid to Process 187 hard wired values of 100m 79y 20k against Fogra 39/ISO Coated v2. These values equate to L36 a65 b58, when the Lab library value is L38 a57 b29. This is a dE76 of 30.1, de94 of 9.7 and de2000 of 11.7


    Stephen Marsh
    Last edited by Stephen Marsh; 10-19-2012 at 12:54 AM.

  5. #5
    Stephen Marsh is offline Senior Member
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    The L*a*b* values for Pantone Plus 187 C are: L37.7 a56.5 b29.9 (taken from ORIS Colortuner Pantone licensed digital library).

    The L*a*b* values measured from the Pantone + Spot swatch in the printed colour bridge are: L38.9 a57.4 b26.2 (uncut i1 pro)

    The L*a*b* values measured from the Pantone+ CMYK swatch in the printed colour bridge are: L41.1 a55.1 b25.1 (uncut i1 pro)

    The (unknown) CMYK device dependent values in colour bridge are: c7 m100 y82 k26. These values when printed in F39/ISO Coated v2 conditions would be approx L38 a59 b37. Again the B value is too high for these hard wired CMYK values to be correct for F39 conditions.


    Stephen Marsh
    Last edited by Stephen Marsh; 10-19-2012 at 01:13 AM.

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    keith1 is offline Member
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    Yes but I'm not talking about print conditions or anything else. All I'm pointing out is that Pantone is inconsistent within it's own guides. One Pantone guide says one thing while another says something different.
    Tpyo likes this.

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    Stephen Marsh is offline Senior Member
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    Quote Originally Posted by keith1 View Post
    PS/ The process values for 187 you list at the bottom of your post are different from others that are available, such as Colour Manager. And this is my point. Which does one use? I only used PMS 187 as an example because it was in front of me. Other colours can differ a lot more from one guide to another.
    This is also my point Keith, we agree! Unknown device dependent CMYK values are of little use. You need to know what the L*a*b* values of the spot colour are, then convert these values to the known device dependent values that you are separating and printing to.


    Stephen Marsh

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    Stephen Marsh is offline Senior Member
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    Quote Originally Posted by keith1 View Post
    Yes but I'm not talking about print conditions or anything else. All I'm pointing out is that Pantone is inconsistent within it's own guides. One Pantone guide says one thing while another says something different.
    As I said in my original post "I believe that Pantone+ Solid Coated (lab) is the latest library."

    It has long been the case that Pantone update their colours, the latest guide is the Pantone Plus series.

    It has also long been the case that people will use a ten year old swatch book as their reference.

    Such is life in the graphic arts!


    Stephen Marsh

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    rich apollo is offline Senior Member
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    Quote Originally Posted by keith1 View Post
    Yes but I'm not talking about print conditions or anything else. All I'm pointing out is that Pantone is inconsistent within it's own guides. One Pantone guide says one thing while another says something different.
    What Stephen is saying, and I agree whole-heartedly, is DO NOT use ANYONE'S prebaked CMYK values. Use the Lab values, and then convert into the appropriate colorspace. For example, playing with Photoshop I get the following CMYK values for PMS 187C under different output conditions:

    US Web Coated (SWOP) v2: C-22, M-100, Y-85, K-14
    FOGRA 27: C-23, M-98, Y-80, Y-15
    GRACoL 2006: C-21, M-100, Y-78, K-14
    FOGRA 29: C-19, M-100, Y-81, K-11

    These are the Adobe-provided profiles with Photoshop CS 5.5 using the relative colorimetric rendering intent.

    The CMYK values will change depending on the output conditions. The same CMYK values will not look the same on #1 coated stock and on newsprint.

  10. #10
    Correct Color is offline Senior Member
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    Yes but I'm not talking about print conditions or anything else.
    Actually, what all these other knowledgeable gentlemen are telling you is that yes, you are.

    The point is that there aren't any absolute Pantone-to-CMYK values, because CMYK is device dependent, which is another way of saying printing condition dependent. The reason you see so many differing CMYK values is that each one is describing a different printing condition.

    If you're printing to a device that has a RIP that includes a PMS library, and you're creating vector files, your best bet is to just call for the solid coated version of the color, and --assuming you're printing with an accurate profile of your device in its current state-- you'll get the closest possible match you can get. Of course, if your profile is off, then there's nothing that's really going to help you, other than properly profiling the device.

    If you're not printing to a device that has a RIP that includes a PMS library, or if you're not sending vector files, the process is a little more involved, and depends in large degree on just what you're trying to achieve, what print process you're using, and what options you have available to you.

    But the only way you can ever be sure that a CMYK value for a PMS color is as close as you can possibly get in your unique situation, is if you're using your exact printing condition profile as your CMYK working space in your design application, and that that profile is accurate. And of course if you do all that, then whatever number you get will be unique, and won't match any value you see in any book anywhere.

    Mike Adams
    Correct Color


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