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- Path: sparky!uunet!mcsun!uknet!mucs!lilleyc
- From: lilleyc@cs.man.ac.uk (Chris Lilley)
- Newsgroups: comp.graphics
- Subject: Re: Pantone to RGB or HSV conversion
- Message-ID: <5465@m1.cs.man.ac.uk>
- Date: 26 Jul 92 22:20:52 GMT
- References: <1992Jul23.005234.29900@msuinfo.cl.msu.edu>
- Sender: news@cs.man.ac.uk
- Reply-To: lilleyc@cs.man.ac.uk (Chris Lilley)
- Organization: Department of Computer Science, University of Manchester UK
- Lines: 63
-
- In article <1992Jul23.005234.29900@msuinfo.cl.msu.edu> rudnitsk@cps.msu.edu
- (Rudnitsky Andrij M) writes:
-
- >Is there a way to convert a Pantone color to either RGB or
- >HSV?
-
- Well, no
-
- At least, assuming you mean 'is there a way to convert a Pantone colour to
- the SAME colour in RGB which will look the same on all monitors'.
-
- >I have a suspicion that Pantone colors can't really be
- >accurately described by RGB or HSV,
-
- Your suspicion is correct ;-)
-
- The colours can be accurately described by any standard, device independant
- colour system such as CIE XYZ or its relatives.
-
- Given the specification for your monitor, and assuming it is gamma
- corrected to make the light output linear, then the CIE specification can
- be converted to an RGB value for *your* monitor and displayed on the
- screen.
-
- >and that the colors numbers are assigned at random.
-
- I don't know if it is random. I suspect they have some sort of system,
- although whether this is publicly available is another matter.
-
- > Is there perhaps a conversion chart?
-
- Some commercial programs use internal tables of CIE specifications for the
- Pantone Process colour range (different from the original Pantone colours,
- which were for spot colour inks). The colour measurements may well be
- proprietary, though.
-
- In principle, the conversion you suggest can be done. It requires:
-
- a) a lookup table to go from the Pantone number to a CIE specification.
- There are not that mant Pantone colours, this should not be a problem.
-
- b) measured values for each colour. With access to the relevant equipment,
- measuring the colours would be no problem from a technical viewpoint.
- However, the Pantone swatch books come with some form of license, whose
- terms I have not seen. This license may well prohibit you from measuring
- the valuers or from making them available publicly.
-
- c) the chromaticity coordinates of the monitor phosphors and white point,
- and the gamma value, to convert from CIE colours to RGB. This is simple
- given the data, which is obtainable from manufacturers.
-
- The main problem is licensing. This is understandable: if this data is
- available, Pantone looses money because their colours can be reproduced on
- screen or printer without a Pantone license (providing they are within the
- range of displayable colours for that device).
-
- Of course, if someone has a list of these values which may be legally
- distributed, post it here!! I would be most interested!
-
- >Andy Rudnitsky rudnitsk@pleiades.msu.edu rudnitsk@cps.msu.edu
-
- Chris Lilley lilley@cgu.mcc.ac.uk
- Computer Graphics Unit, Manchester Computer Center, Manchester, UK
-