What happens to images in a CMYK composite output?

[dominic.martin]

Hi,

Can anyone clarify the following for Pub 2003. I have a document set up
for 4 colour process printing (under the commercial printing tools).
All the text and other graphical elements in Publisher have their
colour values specified as CMYK. The output will be to the generic
colour postscript printer for a CMYK composite image.

My interest is with the images that I'm inserting into the document. If
I have an image created in the RGB colour space, presumeably Publisher
is performing some kind of conversion to CMYK. What if I insert an
image that was already designed for output to the CMYK colour space (I
know in Photoshop you can specify colour references as CMYK)? Would
Publisher perform another conversion and possibly distort the original
colour values or would it recognise the image as CYMK and leave it
alone?

Do people think it's better to just always insert RGB images and leave
the conversion to Publisher or can RGB and CMYK images be mixed in the
document? Any clarification on this would be beneficial. I couldn't
find what I was after on the on the Office site.

Regards,

Dominic

 

[Mary Sauer]

Maybe reading these series of articles can help
Commercial printing
http://office.microsoft.com/en-us/assistance/CH062524641033.aspx

 

[dominic.martin]

Thanks Mary but I have already looked through those and couldn't really
find what I was looking for.

Dominic

 

[Terje Martinsen]

Very interesting point that I would also like to see answered.
Could someone maybe ask Microsoft directly?

Regards Terje

 

[Mac Townsend]

You ask some (unfortunately) excellent questions.

I don't know the answer and I doubt anyone else here has the definitive
answer either. Such would have to come, i suspect, from the developers
group. Perhaps one of the MVPs could forward your question.

But, depending on the tools you have available, you ought to be able to
emperically determine an answer (i.e. experiment). Such a test suite
might be as follows (you could certainly devise your own).

I think I'd build a series of documents each with a condition you wish
to test.

But I think I'd make my own images in Photoshop, perhaps a series of
solid patches of different values. I'd note the values of each patch.
Then I'd save them as tiff and import them (as linked).

For comparison, I might also save these images from PhjotoShop as
Photoshop eps images (use "ascii" encoding and "tiff" header, leave all
the check boxes unchecked).

Perform the different output scenarios to PostScript files. Then I would
distill each and use the eyedropper tool in Enfocus Pitstop to re-
measure the patches. If they are substantially the same or not should be
easily determined.

For this you would need (a) PhotoShop (possibly some other photo editor
might work, Corel PhotoPaint I know would) (b) full version of Acrobat
and Distiller (c) Enfocus PitStop (a full featured time-limted demo is
available at enfocus.com).

If Publisher is internally altering an imported CMYK image I would
expect that the tiff version would be altered but that the cmyk version
would not be (eps are usually not touchable by importing applications).
I would expect some possibly wierd results from rgb eps when printed to
cmyk.

Good luck...and report back, eh?<G>

 

[°°MS-Publisher°°]

If you insert any graphic (not EPS) format into Publisher, the graphic is
converted and stored internally as an RGB PNG file.
Consequently, you will always achieve better output from Publisher even if
you are outputting the final result in CMYK.
If you use an EPS, the file is no way altered, and passes through in
original format to the Postscript printer or PDF file (provided you are
using the full version of Adobe Acrobat - pseudo PDF file makers do not do
that)

Yes, so it is always better to insert RGB pictures into Publisher - except
if using an EPS, however that brings on another set of issues.

Damn mid-summer here and freezing cold. I felt like some good soup, and
knocked up for lunch some sweet potato, pumpkin, capsicum and coriander soup
and it is absolutely magic.
Made two pieces of spelt bread toast with blue cream cheese - what a cheap
wonderful tasting gourmet meal.
Sorry I kept you waiting for the reply, but I had to each my lunch mid-way
through replying.

 

[dominic.martin]

Thanks for the confirmation. So, in conclusion, it looks as if CMYK
images must be linked EPS files. The document should then be output to
the generic Postscript Printer driver and then converted to PDF with
Acrobat Distiller.

I'd be interested to know what the other `set of issues' are that you
mentioned related to EPS?

Regards,

Dominic

 

[kdsdata]

I can't elaborate on the details of conversions that go on by switching
between RGB and CMYK, but I can say that it's not really important to know
that (other than for curiosity sake) for most of us.

I would say that you don't need worry about either, because it's less
important what yo put "into" the output file. What is really important is
"what the printer does with it".

With the variations in toner die-lots, and density variations introduced by
the printer (the machine itself), I would suggest, just prior to wanting the
final output, that you make a "proof" file, take it to the printer and have
them run you a proof copy.

You can then go back to your computer make the colour adjustments on your
graphics, and create the final print file. Sometimes it takes a few
iterations of this process to get the colours re-created the way you want
them.

Usually the colour adjusments are sufficient for subsequent jobs, but if
there is a long period between jobs (die-lots change), and if you are fuzzy
for repetitiveness you may have to do this every time you print another batch.

Good luck. It sound like a lot of work, but you can get excellent results
if you work at it. Even the Pro's do it this way.