Colour separation sans trapping: what's the use?

[Scott_Falkner@adobeforums.com]

I can print colour separations from Acrobat, but without any trapping or overprinting. So black text knocks out, no matter what my trapping settings are in QuarkXPress or InDesign. So what's the use of separations, if trapping and overprint are ignored?

[Aandi_Inston@adobeforums.com]

Trapping is now typically handled in the RIP, but overprinting should
be honoured. Check your Distiller settings to make sure "Preserve
Overprint settings" is on. Also, if you want overprinting to work
with process colours as well as spot, make sure "Illustrator overprint
mode" or "Overprinting default is nonzero overprinting" (mystifying
names indeed) are selected. And finally, make sure your black text is
CMYK black, not greyscale or (especially) RGB.

Aandi Inston

[Scott_Falkner@adobeforums.com]

Check your Distiller settings to make sure "Preserve Overprint settings"
is on.





'tis.

Also, if you want overprinting to work with process colours as well as
spot, make sure "Illustrator overprint mode" or "Overprinting default
is nonzero overprinting" (mystifying names indeed) are selected.




Where do I find those?

And finally, make sure your black text is CMYK black, not greyscale or
(especially) RGB.




Not using RGB. I'm using the "Black" defined in QuarkXPress, mostly. I'm also usign a custom black (0,0,0,100) with it's own trapping values assigned, but no trapping shows. Also used is solid black fills from Illustrator placed as EPS files. The black in the Illustrator files is set to overprint (and does).

[Aandi_Inston@adobeforums.com]

> Also, if you want overprinting to work with process colours as well as
> spot, make sure "Illustrator overprint mode" or "Overprinting default
> is nonzero overprinting" (mystifying names indeed) are selected.
>Where do I find those?

Distiller's advanced settings.

>
> And finally, make sure your black text is CMYK black, not greyscale or
> (especially) RGB.
>
>Not using RGB. I'm using the "Black" defined in QuarkXPress, mostly. I'm also usign a custom black (0,0,0,100) with it's own trapping values assigned, but no trapping shows.

Ignore trapping. Focus on overprinting, which can work.

> Also used is solid black fills from Illustrator placed as EPS files. The black in the Illustrator files is set to overprint (and does).

You mean, in the same PDF, these Illustrator "blacks" do overprint -
but not the XPress overprint? What version of XPress?


Aandi Inston

[Scott_Falkner@adobeforums.com]

Distiller 6
* Preserve Overprint Settings: Check
* Overprint default is nonzero overprinting: check

QuarkXPress 4.11
* Blacks manually set to overprint

Illustrator CS (saved as 8.0 EPS files)
* Blacks manually set to overprint

I send files to a printer, and they do whatever voodoo they do, and the files print trapped. Of course, I need to trap them myself. I test the trapping by printing CMYK separations from QuarkXPress to my colour laser pritner, which is smart enough to turn those four grayscale pages into one process colour page -- pretty slick.

I'd prefer to use Acrobat for this if I can, as I have separation preview, and can be certain that the file I send them separates and traps properly.

However, nothing seems to get trapping to show in the composite PostScript file. All colour knockout, no matter the way they are trapped.

[Aandi_Inston@adobeforums.com]

Maybe we need to look at this "I need to set trapping myself". Quark
does not trap a composite PostScript file. So there will be no
trapping performed unless you write separations from XPress.

If this is a stopper, we don't need to investigate the overprint
further. If it isn't, I'd suggest using the demo of our Quite
Revealing plug-in to view plates, and see whether it shows
overprinting as you would expect.

Aandi Inston

[Scott_Falkner@adobeforums.com]

Quark does not trap a composite PostScript file. So there will be no trapping
performed unless you write separations from XPress




I was under that impression as well, but it seems that it's bnot quite the case. The files I work with include a block of white text that used to be black and manually overprinted in a previous life. I didn't bother changing the trapping method when I was pre-flighting the file, which is complete when I FTP a composite PDF (Distilled from printed PS file) to the printer. The text did not print, and I was told that the Overpint on the white text was the reason. That was the first time I heard that trapping data does end up in a composite PS file. There are other components and colours that I must trap as well.

But, at least I get what's hapenning. Can InDesign include trapping in composite PS files? We are in the process of upgrading our production workflow to use InDesign, but that is a man-on-the-moon-in-this-decade kind of undertaking.

[Aandi_Inston@adobeforums.com]

Trapping and overprinting are different things. Overprinting can get
into a composite file from XPress. Trapping can't.

Aandi Inston

[Scott_Falkner@adobeforums.com]

Trapping and overprinting are different things. Overprinting can get into
a composite file from XPress. Trapping can't.





That's semantics. Overprinting is a method of trapping. However, neither overprint nor trap are showing in my separations (on print or on screen) in my PDF. Someone please tell me I'm not SOL here.

[Aandi_Inston@adobeforums.com]

>That's semantics. Overprinting is a method of trapping.

Yes, but QuarkXPress distinguishes between these two semantic
concepts. Whatever you call them, the results matter.

Trapping is considered to be things like automatically choking
overlapping items. You can specify this in XPress, but it only has an
effect on XPress separations.

I don't know why your overprinting is being lost. This is not a
universal problem, perhaps not even a common one. I can only suggest
you pursue the method I suggested a few messages back - experiment
with Quite Revealing.


Aandi Inston