Re: Preserve Numbers?
Re: Preserve Numbers?
- Subject: Re: Preserve Numbers?
- From: Marco Ugolini <email@hidden>
- Date: Sun, 12 Nov 2006 18:52:33 -0800
In a message dated 11/11/06 8:37 AM, Antonio Garcia wrote:
> They asked me what Colour Management Policy they have to assume with my cmyk
> photos, "Preserve Embedded profile" or "Preserve numbers" ?
>
> "North America Prepress 2" assumes "preserve numbers" as default but I guess
> this changes everything.
This is how the InDesign Help file describes the " Preserve Color Numbers"
option:
--------
Select Preserve RGB Numbers or Preserve CMYK Numbers.
This option determines how InDesign handles colors that do not have a color
profile associated with them (for example, imported images without embedded
profiles). When this option is selected, InDesign sends the color numbers
directly to the output device. When this option is deselected, InDesign
first converts the color numbers to the color space of the output device.
Preserving numbers is recommended when you are following a safe CMYK
workflow. (See Using a safe CMYK workflow.) Preserving numbers is not
recommended for printing RGB documents.
--------
As for the "Safe CMYK Workflow", they describe it in these terms:
--------
Using a safe CMYK workflow
In Illustrator and InDesign, a safe CMYK workflow ensures that CMYK color
numbers are preserved all the way to the final output device, as opposed to
being converted by your color management system. This workflow is beneficial
if you want to incrementally adopt color management practices. For example,
you can use CMYK profiles to soft-proof and hard-proof documents without the
possibility of unintended color conversions occurring during final output.
Illustrator and InDesign support a safe CMYK workflow by default. As a
result, when you open or import a CMYK image with an embedded profile, the
application ignores the profile and preserves the raw color numbers. If you
want your application to adjust color numbers based on an embedded profile,
change the CMYK color policy to Preserve Embedded Profiles in the Color
Settings dialog box. You can easily restore the safe CMYK workflow by
changing the CMYK color policy back to Preserve Numbers (Ignore Linked
Profiles).
You can override safe CMYK settings when you print a document or save it to
PDF. However, doing so may cause colors to be reseparated. For example, pure
CMYK black objects may be reseparated as rich black. For more information on
color management options for printing and saving PDF files, search in Help.
--------
So, summing up, the "Preserve Color Numbers" option is useful when one
wishes to see what a file (usually CMYK) looks like when printed to a given
color space if its numbers are NOT converted to the target color space. For
instance, this may come in handy when one receives an untagged CMYK file,
and wants to see how it prints, for example, within a US Web Coated (SWOP)
v2 color space on a profiled inkjet printer. Using those results, one can
then go on either to apply slight edits or to apply a source profile other
than the one to which the file was printed, until the appropriate one is
found.
Of course, if you have a profiled monitor and are using a properly set-up
copy of Photoshop, this process of applying a source profile and seeing how
the image looks in that color space is done much more quickly and
efficiently.
Regards.
--------------
Marco Ugolini
Mill Valley, CA
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