[Openicc] PDF and rendering intents

[Ann McCarthy]

Rendering intent handling is a weak area in current PDF cm.  This might be
why you see print systems ignoring or overriding the info in the file.

Leonard has agreed to work on upgrading next gen PDF std so that rendering
intent will be specified for output profile separate from input profile.
This is part of what is needed. Specific RI for each source content object
and a separate RI for the output profile.

Think about it.

Rendering intent is essentially a transform selector.

Input profiles and output profiles each have multiple transforms available.

Certain workflow scenarios REQUIRE that the rendering intent for the input
profile (source profile) not be == to the rendering intent for the output
profile (destination profile).

In general, rendering intent selectors apply to one color transform
operation. Once applied, the same selectors should often NOT be used in the
next cm transform in a multi-stage color transform workflow.  So -- more
smarts are needed around when/what RI to use. This really becomes an area
where a workflow system must apply smarts to determine what is appropriate
in the context of the workflow use cases.


Best regards,
Ann L McCarthy
Imaging Systems R&D
Lexmark International, Inc.



On Fri, May 13, 2011 at 10:12 PM, Chris Murphy <lists at colorremedies.com>wrote:

> I am wondering from anyone, but most likely Leonard, what the various PDF
> specs require in terms of rendering intent handling. I know the rendering
> intent can be set in the PDF itself but the questions are:
>
> 1. What is Default? For example InDesign has a Default rendering intent
> option per object, but what is the default? Does this mean "defer to RIP's
> settings?" Or the application default for that object type? Or is there a
> default intent in a spec somewhere?
>
> 2. Are RIPs required to honor the intent setting in the PDFs, or are they
> just suggestions? Or is it context specific? (Suggestion for PDF, but
> required for PDF/X?)
>
> I ask because I see many RIPs that support PDF documents apply their own
> rendering intent settings but the UI makes it ambiguous whether the RIP
> settings override the PDF, or the PDF object intent overrides the RIP, but
> in practice it appears the RIP settings always have an affect.
>
>
> Chris Murphy
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