Diff. between Pantone Formula Guide vs. Color Bridge

[mcallister]

Hi.

I want to know about difference, for offset industry only, in terms of using Pantone Formula Guide vs. Pantone Color Bridge. As far I know the Color Bridge just tells you how your Pantone color could be converted in CMYK or HTMl or RGb.

But in case my customers who have their prefered Pantone colors, how can i deal with that in case they claim me to respect their pattern? I don't want to mix with magic colors in order to approximate that Pantone colors. So, the Color Bridge can help me? I mean, with the info of CMYK estimated for a specific Pantone Color can I change it to get a more approximate Pantone Color?

In case Im wrong what else can i do?

Thanks.

McAll

 

[Stephen Marsh]

Chances are the Color Bridge CMYK values mean little for your printing conditions.

If converting spots to CMYK, start with a L*a*b* Pantone value, then convert to a good ICC profile that defines your printing condition (industry standard or house condition). Absolute Colorimetric rendering intent should be used for evaluation and perhaps conversion.

Over and above the base conversion, one can refine the initial CMYK numbers to only use 3 inks (such as removing Y from blue hues and evaluating that the edited colour has "acceptable" dE values).

Stephen Marsh

 

[mcallister]

Chances are the Color Bridge CMYK values mean little for your printing conditions.

If converting spots to CMYK, start with a L*a*b* Pantone value, then convert to a good ICC profile that defines your printing condition (industry standard or house condition). Absolute Colorimetric rendering intent should be used for evaluation and perhaps conversion.

Over and above the base conversion, one can refine the initial CMYK numbers to only use 3 inks (such as removing Y from blue hues and evaluating that the edited colour has "acceptable" dE values).

Stephen Marsh

Hi Stephen.

Thanks for your support. I apologize in case some terms are not clear for me for now. But I'll try to follor your ideas.

1. About idea #1: it means, so, that using Color Bridge Guide for my printing house, it's not essential or not so relevant, in case I want to copy exactly the Pantone color?

2. How can I get the L*a*b values for a Pantone color (for example, the Pantone 137U)? the conversion process into a ICC profile depends on my PC color profile, calibrated according to the press machine? All those parameters i have to setup, i. e. in Adobe Illustrator?

3. Could you please expand this information more specifically? So sorry, but I want to have the pure technical info in order to explain to my press team.

Thanks so much for your attention.
McAll.

 

[Stephen Marsh]

Hi Stephen.

Thanks for your support. I apologize in case some terms are not clear for me for now. But I'll try to follor your ideas.

1. About idea #1: it means, so, that using Color Bridge Guide for my printing house, it's not essential or not so relevant, in case I want to copy exactly the Pantone color?

Hi mcallister, the Pantone Color Bridge uses a printing condition that does not match what others in the industry generally print to.

As a CMYK recipe is *device dependent*, the fixed CMYK recipe values used in Color Bridge create different colours than what would be achieved if a printer was printing to an industry specification such as Fogra 39 or GRACoL C1. These print conditions would require different sets of CMYK numbers/recipe values to create the same/similar visual colour.

The Color Bridge is useful to visually show customers where a Spot colour is out of gamut for CMYK. I don't find it very useful for obtaining an "accurate" (when in gamut) CMYK recipe for common target printing conditions.

2. How can I get the L*a*b values for a Pantone color (for example, the Pantone 137U)? the conversion process into a ICC profile depends on my PC color profile, calibrated according to the press machine? All those parameters i have to setup, i. e. in Adobe Illustrator?

Lab colours can be obtained by various methods.

You could measure in the colour of a Pantone+ spot colour from the Pantone Plus Formula swatch book with a spectrophotometer or spectrodensitometer.

An easier method may be to reference software that has a licensed Lab based spot colour table/library file (not a CMYK or RGB based library file). From Adobe Illustrator Pantone+ colour book:

Pantone+ 137 Coated = 76L 31a 82b

Pantone+ 137 Uncoated = 77L 38a 69b

Even though Pantone+ 137 has the same ink formula, the perceived/measured colour includes how the density of the solid ink interacts with a given media.

Yes, you will also need the correct CMYK profile to use as your destination to convert the Lab values into CMYK.

Do you print to your own custom “house” printing condition? Or do you print to say ISO Coated v2 / Fogra 39, GRACoL C1 etc?

We can discuss the colour settings conversion settings at a later point...

3. Could you please expand this information more specifically? So sorry, but I want to have the pure technical info in order to explain to my press team.

Thanks so much for your attention.
McAll.

Let me know if the above makes sense, then we can move on.


Sincerely,

Stephen Marsh