Hi!

Many thanks for the work you have done on CMYK features in Prince - it has greatly helped our printing issues.

One thing the printer mentioned to bring down printing costs was to set the colours in the pdf to use a 'solid colour' process. Is this possible in Prince? The slight problem is I'm not entirely sure what 'solid colour' is so I realise I may not have asked the question correctly.

Many thanks!

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At the moment we just do RGB and CMYK colors. There are other color mechanisms in PDF which we don't support yet, but I'm not sure which of these corresponds to solid color. Perhaps further research is needed.

Hi Mike

Yes, quite right, that was a rubbish post. After asking around I discover what I actually mean is Pantone colour. Is specifying colours in pantone possible in Prince (or even in PDF)? This could potentially vastly reduce printing costs for our clients.

Cheers

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I would assume it must be possible to use Pantone colors in PDF, but we currently don't have any way of doing this with Prince or CSS. I'll add it to the roadmap.

Thanks Mike - that's really helpful.

Some of the images we use the colours are specified in pantone. Do you have any idea how Prince will convert those images into the pdf? They seem to look ok in the pdf that's produced but I don't know if they will have been converted to RGB or something?

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Either RGB or CMYK, yes. Unless they are JPEG images?

The issue with Pantone is that you have to license the colours to be able to use them. Pantone aggressively assert their IP rights. Because of that, you usually can't find freely available matching algorithms to convert between Pantone and CMYK or RGB.

On top of that, moste Pantone colors cannot be recreated using CMYK or RGB due to differences in the color spaces (Pantone is based on 14 solid colors).

Do you mean that we would have to license the colours or the guys at Prince would? We buy the pantone colour books and pick the colours from there for the handbooks we produce.

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I understand it's also possible to run a 2 colour print process instead of the full 4 colour process that CMYK needs. Would this be possible in Prince? If you specified all the colours as CMYK but only specified one of the colour parts and left the others at blank would you then be able to run a 2 colour process?

e.g. for a 2 colour cyan and black process colours could be: cmyk(0.8, 0, 0, 0.5) or cmyk(0.4, 0, 0, 0.2). Of course that still wouldn't solve the issue of the images. Cheers!

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To be honest, I really don't know. I think we will need to speak to the actual printer to resolve this issue.

I've only made a cursory look at how Pantone colors are handled in PDF and don't know how deeply Pantone sinks it's IP hooks into graphics software (display -vs- editing) but it seems to me that:

In the offset print world, a "spot color" (pantone or other) is basically a just placeholder which creates a plate/separation/'color channel' in the RIP, and the press operator just makes sure that the appropriately colored (pre-mixed) ink goes in the press for that plate. In the home/office screen/print world, that placeholder color of course needs to be translated to a CMYK or RGB color for printing/display (in the appropriate color space). I assume that Adobe licenses the Pantone look-up table information for inclusion in Acrobat Reader, but I might also assume that Pantone would want Prince to pay a royalty to declare a spot color to be Pantone(TM) 123(C) U(R).

From what I understand, though, PDF has the ability to define user defined spot colors (apparently called "Separation color space") which are defined along with a RGB or (I assume) CMYK equivalent – and this would do the trick for me and I assume a lot of other 'Pantone needs'. If Prince had 'user defined named spot color separations' I could just set up a document with 'MyCorporateBlue' give it a RGB and/or CMYK equivalent for regular use; and then if it is sent to offset printing I could tell the printer to use Pantone XYZ for that plate/spot/separation.

(edited for clarity and with more precise information)

Thanks for the explanation, that sounds like something we could investigate in the future.

Now we have released Prince 8.1, with support for named spot colors using a new @prince-color CSS rule. Documentation will be available soon.