Further on CMYK -> Lab
Further on CMYK -> Lab
- Subject: Further on CMYK -> Lab
- From: Henrik Holmegaard <email@hidden>
- Date: Thu, 22 Mar 2001 19:00:36 +0100
The Distiller 4.0.5 behaviour that converts EPS CMYK tagged in Pshop
with a CIEBasedDEFG CSA into Lab when 'Leave Colors Unchanged' is
selected, losing the total ink limit and black generation, also
occurs in InDesign 1.5.2, but not in Illustrator 9 which quite simply
doesn't support Lab.
If a Pshop CMYK image tagged with CIEBasedDEFG is placed and color
management deactivated in InDesign 1.5.2, there are three PDF export
options :
Set export dialog to 'Leave Unchanged' = Lab
Set export dialog to 'CMYK' = DeviceCMYK
Set export dialog to 'RGB' = DeviceRGB
The problem for users is that color management is done when no color
management is requested. Pshop 6 distinguishes between preserving the
numbers and preserving the color appearance. 'Leave (Colors)
Unchanged' sounds to me like 'please preserve my numbers and discard
the device independent reference'.
When color management is enabled in InDesign 1.5.2, Illustrator 9 and
Photoshop 6, I can't find a way to make them tag a CMYK CSA into a
PDF 1.3 document. This doesn't mean that PDF 1.3 differs from
PostScript 2017 and higher in supporting CIEBasedDEFG, it only means
that Adobe has tried to make a clean break between EPS and PDF 1.3,
which is a good thing - except for the CMYK problem. (The PDF 1.3
Spec yields no hit for 'CIEBased' ... odd.)
The workaround isn't to write a start-up file that makes Distiller
ignore CSAs since InDesign also behaves this way when generating PDF
1.3 directly.
One solution would be to run a color server in front of Distiller,
harmonise all incoming spaces to a single destination space, usually
CMYK, generate the PDF 1.3 file, and then run the PDF 1.3 file
through the color server once more, this time in a hotfolder that
only picks up Lab objects, setting the same CMYK destination profile
as before to reapply the total ink limit and black generation. For
PDF 1.3 generated by InDesign the hotfolder trip is enough.
--
Henrik Holmegaard
TechWrite, Denmark