Support for PANTONE colors

[stefan6419846]

Explanation

I recently stumbled upon a PDF file which would emit

Color /PANTONE 2935 C converted to Gray. Please share PDF with pypdf dev team

Apparently, we currently do not support Pantone colors, although I am not sure about the general licensing situation here.

Resources

Doing some research, I stumbled upon the following public data sources:

• Conversion chart to CMYK at https://www.risinghillmarketing.com/wp-content/uploads/2016/03/pantone-color-bridge-cmyk-pc.pdf
• https://codebeautify.org/pantone-to-cmyk-converter with a hard-coded mapping at https://codebeautify.org/dist/9.2/js/pantonJS.js, but without any source or license hint
• http://www.excaliburcreations.com/pantone.html which can only be used with explicit permission. The values appear to be off compared to above PDF and Javascript code
• https://github.com/adonald/Pantone-CMYK-RGB-Hex/blob/master/pantone_CMYK_RGB_Hex.json based upon the previous website (the repository states the MIT license, but I have some doubts about this)

[pubpub-zz]

I don't know how to manage this: the color definitions seems to be also protected. See page 3:
https://www.pantone.com/media/downloads/customer-service/Pantone_Color_Services_Terms_and_Conditions.pdf

[stefan6419846]

As it should not really hurt, I just sent them a message asking about FOSS usage. Depending on whether we receive a (positive) response, we should be able to either implement this or emit a clear message for this case to indicate that there is nothing we can do about this specific case.

[pubpub-zz]

As it should not really hurt, I just sent them a message asking about FOSS usage. Depending on whether we receive a (positive) response, we should be able to either implement this or emit a clear message for this case to indicate that there is nothing we can do about this specific case.

Or implement a way to pass a colors lookup table

[stefan6419846]

We will have to rely on the lookup table if we want to add support for it - my request to them just got denied.

By the way: For some reason, the previous comment has been added twice, thus I deleted the duplicate.