RE: losing colour in Acrobat

["Debbi Leipold" <debbi@xxxxxxxxxxxxxxxxxx>]

Geez Michael did I offend or alarm you :-)

Although I agree with most if not all of the specs you outlined, I can still
tell you that I find the need to do two versions of documents with
exchangeable graphics.  One to send to my commercial printer which contains
duotone eps graphics (these graphics were created solely in Photoshop).
When using the Adobe 4.2 driver with a scitex dolev ppd (with dov's changes)
I can generate postscript and it spearates correctly.  If I then try to
distill the same file with this driver setup or my distiller driver setup
any page that contains this type graphic bombs out.  If I replace the
graphic with the same but converted to cmyk color it works fine in
distiller.  I need a very clean PDF for on-line documents which are embedded
in my help system.

If I have a tiff file that is anything but cmyk color it will distill as
Black and white.  Yes, I am using the right drivers etc.  I have heard of
many, many other people with similar problems.  This works for many of us.
So, theoretically other solutions should work, but practically I can rely on
this method.

All i can really conclude here is that the way you have to handle a
particular graphic can depend on where and how the graphic is created and
what format it is.  A good first try for problematic graphics is to make
them cmyk.

Hope this helps clarify a bit.

Debbi
> -----Original Message-----
> From: michaelr@cdn-mail.dn.itg.telstra.com.au
> [mailto:michaelr@cdn-mail.dn.itg.telstra.com.au]On Behalf Of Michael
> Richards
> Sent: Wednesday, October 21, 1998 6:54 PM
> To: Debbi Leipold
> Cc: Dov Isaacs; Thomas Regner; mark barratt; framers@omsys.com
> Subject: Re: losing colour in Acrobat
>
>
> I am getting a little confused here, folks, and this topic is suddenly
> becoming extremely profound!
>
> Debbi, may I ask you to clarify your reply a little?
>
> Specifically the phrase "ppd fixes to  use cmyk". From the
> little I know of
> the pdf format internals it's my understanding that:
>
>          1) Internally pdf can have objects in a single file with
> different
> colour
>              models, i.e. rgb, cmyk, cie et al (but NOT indexed
> colour such as
>              in all GIFs and most TIFFs)
>
>          2) That (and from here on I will assume eps graphics
> only to sidestep
>              other issues!) if the eps COLOUR SCAN is rgb, the rgb colours
> pass
>              straight through Distiller, HOWEVER
>
>           3) Acrobat Reader/Exchange DOES apply its own transfer curve to
> display
>              these colours, so they might look a little different
> from those
>              you were expecting.
>
>           4) If the eps COLOUR SCAN is cmyk, distiller turns this into rgb
> using
>              (roughly speaking!) the notorious Photoshop CMYK seperation
> formula
>              but in reverse, resulting in wishy washy colours
> without strong
> reds,
>              magenta-muddied blues, etc.
>
>           5) If you set distiller to pass through cmyk AS cmyk,
> the display on
>              screen in Reader/Exchange is very colour saturated. That's (I
>              beleive because the coloour-draining algorythm of 4) has been
> side
>              stepped.
>
> I say COLOUR SCANS as things are a little different for Duotones and
> Illustrator vector drawings. This is (in simplistic terms!!!) because both
> these formats have internal, explicit info in the eps file
> telling the RIP or
> whatever the rgb representation of the spot colour(s). Another
> topic. Let's
> not muddy the waters further!
>
> Now, (deep breath) Debbi, do you mean cmyk in, rgb out? Or cmyk
> in, cmyk out?
>
> BTW, a good way to get a decent colour sep on Photoshop is to use the Soft
> Light/Hard Light trick. This means:
>
> 1) SCAN in RGB (D'oh! That's how you do it anyway!)
>
> 2) Change the mode to CMYK.
>
> 3) Then, in the layers pallette, double click on the "Background
> Layer" and
> "un-flatten" the image by renaming the layer in the resulting dialogue as
> "layer 1" or in fact anything other than "Layer 0".
>
> 4) Make a new layer on top of the old. Its mode is either "Soft Light" or
> "Hard Light" (if you want REALLY STRONG COLOURS!!!!!!)
>
> 5) Now, make sure the old layer is active and copy its entire
> contents to the
> clip board.
>
> 6) Make the new layer ("Layer 2" most likely) active, and paste.
>
> 7) Wow! what a great seperation! If it's a bit extreme, reduce layer 2's
> opacity to 50% or whater.
>
> MAGIC!
>
>
>
> Debbi Leipold wrote:
>
> > Dov et all,
> >
> > I disagree. I have found that PDF will not display process
> color correctly
> > and that is necessary even with all of the "right driver" and
> ppd fixes to
> > use cmyk.  i think Shlomo agrees with this as he and I
> discussed it at the
> > conference.  Maybe it is a bug but it is definitely an
> accomodation most of
> > us have had to make.
> >
> > Photoshop generated eps with two colors must be duotone to separate and
> > display correctly in pdf.
> >
> > Any other screen capture type illustration in tiff must be cmyk to work.
> >
> > These are the rules I have found to be fulproof when converting color to
> > PDF.
> >
> > Debbi
> >
> >
>
> <snip of earlier threads>
>
> --
>              _   _        Michael Richards
>             ( \ / )       Email:  michaelr@ind.tansu.com.au
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