Re: Acrobat 8 Color questions
Re: Acrobat 8 Color questions
From: Rich Apollo <email@hidden>
In Acrobat 8's Color Settings why is there no place to set a
rendering intent? Is there no way to specify a rendering intent for
the conversion of a document? What rendering intent gets used
and how
is that determined?
PDF files have a rendering intent as part of the file
specification. In
other words, there is never any question as to what rendering intent a
particular object should use, because the PDF graphics state has a
rendering intent, and its default is Relative Colorimetric. You can
override the rendering intent on a single-object conversion by
using the
touchup object tool, then right-click and go to the properties
panel and
select the "color" tab. The rendering intent of the object selected is
reflected in the panel, and you can change it before clicking "Convert
Colors."
So, is the RI dependent on the Color Settings of the application that
created the PDF? The PDF has an embedded RI and every object within
the PDF has an embedded RI? So, if you repurpose a PDF, which RI gets
used? Is Relative Colorimetric the default for the PDF specification,
or is it the default because that is the default of the North
American Prepress color settings file? And is Preflight the only way
to view the RI for the PDF document?
Also, could someone set me straight on "Device" colors and
"Calibrated" colors, please? From the help menu I'm getting that
"Device" colors refer to untagged elements, and "Calibrated" refers
to elements tagged with device-independent profiles. So, "Calibrated
CMYK" should be an impossibility, right? So, would elements tagged
with device-dependent profiles fall into a third category that
doesn't get displayed in the Convert Colors dialog?
When we talk of "device-indepenent color" we mean that colorspaces
have
profiles associated with them, so that we know what the numbers mean.
"Device-independent profile" is probably a documentation error--
there's
no such thing, except for abstract profiles, which almost no
application
supports. So, Calibrated CMYK does makes sense. (Was this explanation
about "device-indpendent profiles" in Acrobat's documentation?)
I was paraphrasing. I understand "device-independent" and "device-
specific" color. It's Calibrated and Device that I don't grasp. Let
me try again.
From the help menu I'm getting that
"Device" colors refer to untagged elements, and "Calibrated" refers
to elements tagged with profiles of device-independent color spaces.
So, "Calibrated
CMYK" should be an impossibility, right, as CMYK is always device-
specific? So, would elements tagged
with profiles of device-specific color spaces fall into a third
category that
doesn't get displayed in the Convert Colors dialog?
Now, in the PDF fixups area we have Calibrated and Uncalibrated. We
also have "Decalibrate" as a conversion option. Neither
"Uncalibrated" or "Decalibrate" appear in the Help documentation.
The documentation goes as follows:
"Objects with untagged RGB data (DeviceRGB) convert from the working
space RGB profile to the CMYK gamut of the destination space. The
same is done with untagged CMYK (DeviceCMYK) and grayscale
(DeviceGray) values.
Objects in device-independent color spaces (CalGray, CalRGB, or Lab)
can be preserved or converted. If converted, Acrobat uses the device-
independent object’s embedded profile information.
Objects set in spot colors (including Separation, DeviceN, and
NChannel color spaces) can be preserved, converted, or mapped
(aliased) to any other ink present in the document. Spot colors can
also be mapped to a CMYK process color, if the process color model of
the destination space is CMYK. Spot colors mapped to other inks can
be previewed in the Output Preview dialog box."
Rich Apollo
G7 Certified Expert
Adobe Certified Expert, Photoshop
314-344-1144
email@hidden
www.prioritylitho.com
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