[GM-help] Wrong colorspace-conversion for eps-files

[Aike J Sommer]

Hi,

we get wrong results trying to convert CMYK EPS-files. Other files convert
just fine!

The command is:

gm convert test.eps -profile icc:cmyk.icc -profile icc:rgb.icc -colorspace RGB
test.png

And gives the warning:
gm convert: Unable to assign profile (Colorspace color profile mismatch).

(and produces bad colors)

The same command works for CMYK TIFF-files for example.

Is there anything we're doing wrong?

I do have a test-image i can attach if needed, it's pretty big though (2MB),
so i dont know if it's wanted on list!

(Please keep me on CC, as i'm not subscribed to the list.)

Thnx!
Aike

[Bob Friesenhahn]

Post by Aike J Sommer
we get wrong results trying to convert CMYK EPS-files. Other files convert
just fine!
gm convert test.eps -profile icc:cmyk.icc -profile icc:rgb.icc -colorspace RGB
test.png
gm convert: Unable to assign profile (Colorspace color profile mismatch).

The reason for this is that GraphicsMagick uses Ghostscript to render
the Postscript and an RGB Ghostscript driver is used (as specified by
delegates.mgk). Getting this to work would require a Ghostscript CMYK
driver (see output of 'gs -h') which preserves original CMYK values
(not translated for some printer) and is also a supported input format
for GraphicsMagick. It would also be necessary for the EPS to be
composed in CMYK.

If Ghostscript supports a suitable driver, then it could be engaged by
adding another entry to delegates.mgk and adding a minor update to the
source code so that '-type ColorSeparation' prior to the file name
would invoke that entry.

As an alternative, it seems that recent Ghostscript has added some
color management support (using a Postscript model) so perhaps there
is a way to accomplish color management inside of Ghostscript (not
something that I know anything about).

Post by Aike J Sommer
I do have a test-image i can attach if needed, it's pretty big
though (2MB), so i dont know if it's wanted on list!

The list would probably not pass such a large file. However, a sample
CMYK EPS file is useful for testing. You can email it to me directly.

Bob
--
Bob Friesenhahn
***@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/