Overprint Preview Not Working

[Harry_Redknapp@adobeforums.com]

Ok in Quark bring in a greyscale pic in a box with no background - position over another box with a background - default Quark trapping behaviour is to overprint the image resulting in mix with the background color.

Composite/Separation and Overprint Preview views in ACrobat 7 show the greyscale image as knocking out the other object -

(however when you open the pdf in Illustrator and move the image you can see the underlying object.)

[Aandi_Inston@adobeforums.com]

>Composite/Separation and Overprint Preview views in ACrobat 7 show the greyscale image as knocking out the other object -

Have you confirmed that the object in the PDF has the overprint
setting (e.g. with Pitstop)

>
>(however when you open the pdf in Illustrator and move the image you can see the underlying object.)

That isn't really connected to overprinting.


Aandi Inston

[Harry_Redknapp@adobeforums.com]

when I send separated postscript to a RIP and recombine to composite - I can confirm that it is overprint

[MarkATS@adobeforums.com]

when I send separated postscript




From quark or Acrobat?

[Harry_Redknapp@adobeforums.com]

Also in built Preflight check with Acrobat PDF/X1-a under Graphics Properties for overprint fill says true

[Aandi_Inston@adobeforums.com]

>Quark...

So that hasn't verified that the PDF has this element overprinting.

>When I sent separated postscript from Acrobat the seps show knockout.

So the overprint preview is a CORRECT preview of what would happen if
Acrobat makes separations!

It might be because the image is greyscale. Try making it CMYK. Or it
might be Distiller settings.

Aandi Inston

[Harry_Redknapp@adobeforums.com]

No Aandi - reread the first post...

Test
- In Quark bring in a greyscale pic in a box with no background - position over another box with a background color such as Cyan - Quarks aburd trap default is set to overprint the greyscale image.

- When a PDF is made - the overprint cannot be seen in Overprint view - it appears normal, also the separation view is incorrect and the CMYK % values are incorrect

- If you view the imporetd PDF in Indesign via a pic box and look at Outpuut Preview - Separations - it correctly shows the greyscale image mixing with the background color.

-I have been told this is a fault in Acrobat - viewing greyscale images set to overprint over colored vector objects - but you can see the results correctly in Indesign.

[Aandi_Inston@adobeforums.com]

It depends what you mean by "correct". There are complex rules about
overprinting different color spaces. Original rules for PDF meant that
process colors did not overprint AT ALL. A rather complicated change
means that this is now possible. However, the rules for overprinting
greyscale have remained unclear.

However, the PDF Reference now has a clear table showing the defined
PDF behaviour in various cases. Crucially, this includes a rule:
overprinting does not apply to images (though it may apply to
ImageMask), and overprinting does not apply to DeviceGray. Given this,
it seems InDesign is incorrect. Acrobat's separation preview and
separation production both follow the rules.

Will Adobe change the rules for PDF, or will they change InDesign? Who
knows. What you should do is try to only work within the confines of
what is possible in BOTH the worlds you work in: XPress and PDF. So,
if you want to overprint greyscale, use CMYK, and don't use images.

Aandi Inston

[sws@adobeforums.com]

Have you tried saving the original in a different format prior to placing in Quark? For example, I would expect a TIFF file to handle this better than an EPS.

[sws@adobeforums.com]

I tried this with a grayscale TIFF image and worked as expected. Grayscale image was overprinting a Pantone Solid Coated Spot color when Overprint Preview was turned on in Acrobat.

[Harry_Redknapp@adobeforums.com]

sws - try it with a process colour or just make the spot; process equivalent - you will have a different result