Re: PDF x3 output intent
Re: PDF x3 output intent
- Subject: Re: PDF x3 output intent
- From: Olaf Drümmer <email@hidden>
- Date: Tue, 30 Aug 2005 22:55:40 +0200
The destination profile in a PDF/X file's OutputIntent reflects what the
intended final printing condition looks like. It's a good idea to use a
destination profile that actually does that - as it also makes sense to
prepare the contents of the file for that very same printing condition.
Ever printed a commercial page on a newspaper press (or vice versa)?
Liked the result? Maybe not.
So what about stuff in a PDF/X-3 file that isn't in device CMYK (i.e.
colors separated already for the final printing condition's CMYK inks)
yet? It's relatively simple: use the ICC profiles (or Lab info) tagged
to the RGB (or Lab) objects as source, honor the rendering intent and
convert that to the CMYK color space by means of the destination
profile. Voila.
Now what if you have a PDF prepared for SWOP but your press setup (type
of printing process, paper, inks, ...) is not exactly a SWOP printing
condition? Well, speaking very strictly that's beyond the scope of PDF/X
(which is a piece of information not always considered helpful by people
asking that question...). There is actually no easy answer, as the PDF/X
standard can't know what your customer wants. Whether that customer
insists on a close match with a SWOP appearance (that maybe bot printed
elsewhere, or last year, or ...), or whether that customer will be
disappointed by the print result on a commercial offset press with
expensive glossy coated paper if it looks SWOPish...
Anyway, in such cases you'd have to go from the CMYK specified in the
PDF/X file to the CMYK of the actual printing condition - by using
'regular' ICC based conversions, or DeviceLink profiles, or ... For any
objects in a PDF/X-3 file that aren't (device) CMYK yet they'd have to
be converted to the CMYK of the destination profile first and then from
there to the CMYK of your actual printing condition (actual technical
solutions may be able to squeeze this into one conversion step but from
a conceptual point of view there are two steps).
Olaf Druemmer
email@hidden wrote Fri, 26 Aug 2005 14:35:38 -0700:
>Hello all,
>
>My understanding is that typically in a PDF X document the output
>intent would be specified as the profile for the printer/press for
>which the colour data was prepared. So if you separated all your images
>to, and proofed to, say, SWOP v2, then this would be the output intent
>profile.
>
>What about PDF X3 documents, which allow RGB/Lab data, in addition to
>CMYK? So if I have a PDF X3 file that contains both RGB and CMYK
>objects, what do I set as the outputintent? My RGB working space?
>
>Thanks,
>
>Matt Larmour
>
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