Transparency flattening - unwanted color added to transparent PSD file

[peterchristensen]

Hi people,

I´m in desperate need of help here

Recently (after switching to CS3) I began experiencing frustrating problems in relation to (what I think is the problem) transparency flattening.

The problem seems to evolve in the printing process where "something" messes up the transparency by adding a 1% (typically) magenta color to the transparent flattened image. (I´m using transparent PSD-files)
This means that the bounding box-area of the image is actually visible in print! I can see this on my own prints (tested on several in-house printers), but worse is that I´m having the same problem with the material I receive from the printing house.

- When I check my PSD files in Photoshop there is no color but a transparent background.
- In Indesign I´ve tried a lot of different output settings and job option files but with the same result.
- In Acrobat my "output preview" measures no deviations, but when I (touch up tool > right click) edit image from inside Acrobat and the image file opens up in Photoshop the 1% is added.

For now I´m dealing with the problem by adding clipping paths to my PSD files which is a pretty untenable situation!
Apparently the problems seems to occur also on transparent .tiff filer etc.

I´m working in CS3 on OSX and I haven´t changed my workflow whatsoever since CS2.
The printing house is aware of the problem but haven´t experienced the problem before.


Anybody recognises this issue and know how to fix it?

 

[apepp]

...very odd indeed, if acrobat isn't picking up a dot, yet photoshop is via edit image, and that your printers proofs are also coming back with extra highlight dots...

...when highlight areas appear to be gaining dots, it is usually a sign of color conversion, by way of convert to profile, either in photoshop (from rgb to cmyk, or cmyk profile to another cmyk profile)...

...worth a check that you have your color settings synchronized via bridge across the adobe suite...

...when you print to postscript or export to pdf 1.3, check that you have convert to destination (preserve numbers), or no color conversion selected, though i imagine you have tested these areas...

...tried the pdfx1a?

...what happens when you try a pdf version higher than 1.3 from direct export from indesign?

...is there a spot color sat underneath the transparency?

...when you print to your own printer, ensure your driver isn't performing color management, only indesign...

Andrew

 

[eugenetyson]

Don't flatten the transparency. Don't use any image compression. There really isn't a need to, but people do anyway.

If the 1% dot is just in the highlights then I wouldn't worry too much about it. Print needs at least 3% to hold on plate to blanket to paper.

Try using Acrobat 5 for making the PDF you'll notice the Transparency Flattening options aren't available.

Also, opening up an image from Acrobat is not a good thing. You shouldn't need to do this. Use the tools, (find the separations preview) and run your cursor over the areas you are think there are dots being added, you should get an accurate reading from the Acrobat file itself. You shouldn't open the image from Acrobat, it's likely that you will force the image through another conversion process and that's what's happening the image.

From my experience, whatever the image is in your InDesign is the image it is when it's printed, exactly the same.

But I wouldn't be too concerned even if a 1% dot was being added, it's miniscule.

 

[jmgalvin]

You might try trashing preferences for both Indesign and Acrobat and then see if the problem is still there after relaunching.

I still always export to PDF compatible with Acrobat 4 (1.3). That version seems to avoid a lot of possible problems at output.

Using OSX 10.3.9 & 10.4.11 on a G4, G5 & Intel Macbook

 

[apepp]

...a 1% dot in a CTP situation is definitely capable of being held on press, running to film might be a different story...

...if it is 1% yellow, you probably won't see it, but a trained eye can certainly see a 1% dot of magenta, cyan or black on a white background. Particularly with a press minder who is as vigilant as ours is...

...we've come across this before, but that was because the photoshop file did have a 1% dot in the transparent areas, simply because the layer mask was at a 99%, and not 100%...

Andrew

 

[peterchristensen]

Thanks for all your great input - I´m really thankful. It is indeed a very odd problem and we´re gradually turning mad here at the bureau!

EUGENE:
I recon that there isn´t really any reason for editing images from inside Acrobat, but as "Output preview" doesn´t measure anything, that was actually what got us on track of the problem in the first place. The 1% is simply added on the "edit-from-acrobat" PSD, but not in the original source-PSD. That doesn´t make sense (!), so your point about "something happening from conversion" might be true. But then again; we see it on the brochures etc. we receive from the printing house. The problem isn´t just a preview problem or anything screen-buggish.

APEPP:
You´re right: a 1% magenta is certainly visible!
- No we haven´t got any spot colors (may have sometimes, and I know off this issue, but I don´t think that it is the problem in this case)
- I´ll check up on the color management/bridge synch. This is actually one of the (few) things we have´nt tested thoroughly.
- We have tested a lot of settings (prints, output preview as well as edit image from Acrobat) but I can´t say that we´ve actually seen results from the printing house on all these tests. Still, anything from early PDF standard settings to the massive load of job option files we receive from the different printing houses, apparently turns out with the same buggish 1%.


To add further confusion I´ve checked some old (CS1+2) generated PDF´s, and here the 1% is also added, BUT: on the actual print there is nothing to be seen! This could suggest that the problems is the printing houses´ - that "something" happens there during rip or anything. It could also suggest that something has happening since out switch to CS3.
How, and why suddently now, that the million dollar question....


So much for brevity

 

[eugenetyson]

Peter, I said originally that 1% won't be seen on printing, because the dot is so small it won't hold on the plates, no ink can stick to a 1% dot, let alone survive the transfer from plate to blanket to paper.

But that doesn't solve your problem!

Ok so when you open the image in photoshop, do you measure the reading with the eyedropper tool?

If you do, have a look at what settings it's at, certainly in any version of photoshop I have, there is the option of Point Sample, 3 x 3 Average, or 5 x 5 average.

I can't replicate your problem here. But even if I could, I wouldn't be too worried about it.


Another thing you should check

On the Acrobat Output Preview, make sure the colour settings are set to the same as in photoshop.

In my Acrobat it always opnes up using WEB SWOP, but in Ireland I only ever use Euroscale Coated V2, (or the uncoated v2, depending on finishing stock).

So make sure your applications are properly colour managed.

You should also make sure that when you generate the PDF that you use the correct colour management system, so I always make my PDFs to be Euroscale Coated V2, in my Acrobat I view the output preview using Euroscale V2.

 

[apepp]

...definite head spinner this one...

...my take on it is that if acrobat output preview is measuring 0% in the whites, then if any color is going to be added from this point it would be at the rip for plate and proof stage. If you have pitstop, does the image have a tagged profile?

...choosing edit image in acrobat and then preserving the profile in photoshop still ought to read 0%...

...also, if this is a regular occurrence it would also point to a profile conversion problem, rather than a one off job issue...

...1% being held on press can be dependant on what output provider you use, if you used us, the file would print with a 1% dot, but only if the artwork had that 1% in the first place...

...out of interest, have you sent one of these troublesome pdf files to another reliable provider to test on rip, as a process of elimination?

Andrew

 

[eugenetyson]

What would be great, if the original person who posted could use

http://www.yousendit.com

and put a link up here so we can download the file and test it ourselves, sometimes we need to see the problem to diagnose it.

If you are sending it via yousendit then send it to your own email address, then you will be given a link and you can post that link here, we can then download the file, if you could highlight the problem area in the post, that would be great.