Color values for paint matching?
Color values for paint matching?
- Subject: Color values for paint matching?
- From: Eric Bullock <email@hidden>
- Date: Wed, 23 Jul 2008 16:03:40 -0400
- Thread-topic: Color values for paint matching?
Does anyone know what kinds of color values are used in matching paint
samples? For instance if I take my sample to a paint store and they put it
in their "matching doodad", what kind of colorimetry is it recording? Lab?
Lch?
Cheers,
: : : : : :
Eric Bullock
Manager of Information Technology
Center for Digital Imaging Arts at Boston University
www.cdiabu.com
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> Date: Wed, 23 Jul 2008 12:03:39 -0700 (PDT)
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> Subject: Colorsync-users Digest, Vol 5, Issue 246
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> 1. describing opaque or translucent (email@hidden)
> 2. Rendering intents in source profiles? (Uli Zappe)
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> Message: 1
> Date: Tue, 22 Jul 2008 17:38:40 -0500
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> Subject: describing opaque or translucent
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> Hi,
>
> I've been asked to test printing with white over previously printed or
> colored media.
> The desire is for the white to completely cover the printing or original
> color.
> Unfortunately it does not. Now I have to report results.
>
> Is there a standard way to describe this situation?
> For example - possibly certain types of color information are more
> meaningful than others?
>
> Of course I could simply indicate the Lab values of the original media
> color, and then
> provide a second Lab value for the area where white has been applied.
> Is it this straightforward?
>
> Thanks in advance for any suggests.
> Greg
>
>
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> ------------------------------
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> Message: 2
> Date: Wed, 23 Jul 2008 17:31:23 +0200
> From: Uli Zappe <email@hidden>
> Subject: Rendering intents in source profiles?
> To: ColorSync user <email@hidden>
> Message-ID: <email@hidden>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed; delsp=yes
>
> Hi everybody,
>
> while working on the scanner profiling part of the Mac Life color
> management review (I'll report the results when the new article will
> be published), I wondered what rendering intents actually mean for
> source profiles, i.e. for profiles whose A2Bn tags are used.
>
> For instance, take the classic example of a conversion from working
> space to printer space. Since the printer space is smaller, gamut
> compression or clipping obviously has to be performed. *But* this
> should take place in the B2An tag of the printer profile (= target
> profile), which "knows" about the limitations of the printer and can
> adjust the gamut accordingly. I don't see which role the working space
> profile (= source profile) could actually play in its A2Bn tag, since
> the PCS will by definition be able to represent all colors, so
> whatever colors the working space comprises, there will be no need to
> perform gamut compression or clipping when converting colors from the
> working space to the PCS (which is what the A2Bn tag does).
>
> So why are there rendering intents for A2Bn tags, and what do they
> actually do? The ICC spec does define separate perceptual,
> colorimetric and saturation intents for A2Bn tags (A2B0, A2B1 and
> A2B2), and if you test real world profiles as built by e.g.
> ProfileMaker, you will find that they do produce different PCS Lab
> values for the three intents. But according to which logic??
>
> Thanks a lot in advance for any insight!
>
> Bye
> Uli
> ________________________________________________________
>
> Uli Zappe, Solmsstraße 5, D-65189 Wiesbaden, Germany
> http://www.ritual.org
> Fon: +49-700-ULIZAPPE
> Fax: +49-700-ZAPPEFAX
> ________________________________________________________
>
>
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