[Openicc] The OutputIntent and Color Managed Printing

[Michael Vrhel]

I agree that in the special cases where you have varnishes, embossing etc, 
proofing/retargeting would be an issue with that extra stuff handled likely 
outside an ICC workflow.

Per the ISO PDF specification, you can have multiple Output Intents in a 
generic PDF file.   I have never seen such a file in the wild, but it is 
clearly allowed according to the specification.   With the PDF/X spec, 
things are much more restrictive.

Michael




-----Original Message----- 
From: Chris Murphy
Sent: Monday, May 20, 2013 1:24 PM
To: Open ICC Color Managment
Subject: Re: [Openicc] The OutputIntent and Color Managed Printing


On May 20, 2013, at 11:41 AM, Michael Vrhel <michael.vrhel at artifex.com> 
wrote:

> Personally to me, I don't see any difference in the solution to a 
> retargeting problem and a proofing problem.

If the source PDF is ICCBased or CMYK only, it's pretty straightforward and 
I'd say there's no difference. But if the document calls for spot colors, 
embossing, varnishes, etc. then there could be a big difference. A 
particularly good proof would either extract that channel or layer to a 
separate page (with registration marks intact), or mark it with a pattern. 
Whereas retargeting to a composite device it may be appropriate to drop such 
effects entirely. So it's that less than 1% exception that instantly turns 
into a manual handling, arts and crafts type scenario.

>
> Furthermore, more than one output intent (i.e. an arary of output intent 
> dictionaries) can be present in a PDF document.

I'm pretty certain in all current PDF/X's that only one dictionary is 
allowed. The proposal for future PDF/X to be based on PDF spec 2.0+ is for 
multiple dictionaries (e.g. per page output intent), so that a cover or 
insert pages can be defined for printing on different media, while the whole 
document is still in a single PDF.

>
>> * Ghostscript uses the OutputIntent as a proofing profile and the
>> sOutputICCProfile is used to specify the print profile of the output
>> device
>
> The presence of (an) output intent(s) in a PDF document basically suggets 
> that re-targeting is likely necessary, if none of the output intents 
> matches the sOutputICCProfile color space. But re-targeting is IMO not 
> necessarily the same as proofing.

Retargeting should not be expected, proofing should be expected. That's 
about the only difference I can think of.

Retargeting implies the PDF/X was prematurely or incorrectly created, such 
that the Output Intent was set contrary to the actual printing condition.

Chris Murphy
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