To trust submitted PDF's

[imagesetting]

Hi,
We have an old PS LVL 3 RIP for our Large Format Printer, we have many problems with transparency from clients submitted PDF files, we request they submit a PDF/X-1a:2001:

Submitting PDF Files

to ensure transparency is flattened. But often we need to rasterise files in Photoshop as the RIP simply does not deal with these submitted 'flattened' PDF/X-1a files correctly.

Often we request clients submit application files (ie Indesign or .ai files) for us to process here, rather than accept PDF's.

We are going to upgrade to the latest RIP that will be capable of handling transparent artwork - using the Adobe PDF Print Engine (PDF/X/4:2010).
I understand this will not require files to be Postscripted prior to output, and PDF with Live transparency will be flattened in the RIP.
Can I ask opinions if there are instances where you could not trust this up to date version of the Adobe PDF Print Engine to correctly flatten files, or could you just accept anything and trust it to output (Prepress Nirvana - something I doubt exists).
Often we dont always know what clients do to create their PDF's - and wonder if you should ever trust them if the source workflow is unknown

 

[leonardr]

Hi,
We have an old PS LVL 3 RIP for our Large Format Printer, we have many problems with transparency from clients submitted PDF files, we request they submit a PDF/X-1a:2001:
to ensure transparency is flattened. But often we need to rasterise files in Photoshop as the RIP simply does not deal with these submitted 'flattened' PDF/X-1a files correctly.

Photoshop is _NOT_ a PDF RIP!!

If you feel the need to rasterize a PDF before sending to print, PLEASE use Adobe Acrobat to "Save as TIFF/PNG/etc.".

 

[Stephen Marsh]

Can I ask opinions if there are instances where you could not trust this up to date version of the Adobe PDF Print Engine to correctly flatten files, or could you just accept anything and trust it to output (Prepress Nirvana - something I doubt exists).

From what I understand (and I may be wrong), transparencies are not "flattened", as flattening is a PostScript thing. Transparency is a native feature with APPE. I have not had enough experience with APPE to know when/where to trust it over traditional PostScript input. You may need to test print the same file both ways, then repeat with other files until you have developed a "gut feeling" for your typical client files and your device.

Often we dont always know what clients do to create their PDF's - and wonder if you should ever trust them if the source workflow is unknown

One can use the Acrobat file menu, Document Properties command to see what the source Application, PDF Producer and PDF version are - which may give you a clue on how "trustworthy" any given PDF is. Additionally, one would probably hit the file with a PDF preflight and or manual inspection using the Advanced > Print Production > Output Preview (separations and object inspector) and perhaps the Flattener preview.

As leonardr from Adobe states, Photoshop is not a general purpose PDF RIP, however you will likely see some difference in how edges are rendered between the Acrobat raster export method and using Photoshop. Photoshop adds "better" anti-aliasing to the rasterized PDF, so if you use the Acrobat > Export method you may find that you will need to export out at a much higher resolution and then to resample the image down in Photoshop to smooth out the edges a bit.


Regards,

Stephen Marsh

 

[imagesetting]

Thanks for your replies.
I understand Photoshop is not a RIP.

"transparencies are not "flattened"" - so do I read the context of all Adobe 'Flattening' options wrong - which would support what I've always felt, flattening from with Adobe apps (Indesign/AI/Acrobat) never seems to resolve our issue. Only Postscripting will flatten files correctly.

"developed a "gut feeling"" - how funny, but not really, so nothings changed in all these years then, I wonder if anyone with more experience of the APPE would know if it can be trusted to flatten 'live transparency' ??

 

[Tech]

Photoshop is _NOT_ a PDF RIP!!

If you feel the need to rasterize a PDF before sending to print, PLEASE use Adobe Acrobat to "Save as TIFF/PNG/etc.".

This is a common practice though, unless you start removing the feature from Photoshop. You'll be surprised how few end users know they can "save as" .tif/png/etc from Acrobat. People need to use what is convenient and intuitive, not what is "correct" in documents/practice. Working solutions are better than "you can't do that" because it wasn't designed that way.

 

[mattbeals]

This is a common practice though, unless you start removing the feature from Photoshop. You'll be surprised how few end users know they can "save as" .tif/png/etc from Acrobat. People need to use what is convenient and intuitive, not what is "correct" in documents/practice. Working solutions are better than "you can't do that" because it wasn't designed that way.

People need to use what is correct, not what is convenient. Simply being convenient does not make it correct. Removing the feature from PhotoShop isn't the answer. Maybe having PhotoShop behave the same as Acrobat is. But it sounds like more education is needed. Maybe reading a manual or two as well. There are also reasons that you "can't do that". Usually because you cannot/do not achieve the desired result.

 

[imagesetting]

No I didn't know you could save out as a TIFF from Acrobat, would that Flatten correctly ??
I agree, if your in the know, in the industry and have lots of prepress experience your workflow is as good as anyone else's.
I've been a bit out of the loop for a while, and have come back to discover their is still no 'holy grail' - after all these years, I guess it was too much to expect such a complex process as Postscript imaging to be whittled down to a restricted set of simple process steps - in view of all the applications out there, I hoped Adobe's CS packages might have come close. I guess the applications solve one issue but then add another as they develop. Transparency now, what will be next.

 

[[email protected]]

To trust submitted PDF's

"developed a "gut feeling"" - how funny, but not really, so nothings changed in all these years then, I wonder if anyone with more experience of the APPE would know if it can be trusted to flatten 'live transparency' ??

I have used Prinergy Workshop with APPE and have had no problems with transparency. Transparency is flattened when the final tiff file is written for output. The only problem I have had with transparency with auto trapping. Always preview the final tiffs to check for errors.

 

[Stephen Marsh]

"transparencies are not "flattened"" - so do I read the context of all Adobe 'Flattening' options wrong - which would support what I've always felt, flattening from with Adobe apps (Indesign/AI/Acrobat) never seems to resolve our issue. Only Postscripting will flatten files correctly.

No, this is not what I was saying. PostScript can't use transparency, so it has to "flatten" first. PDF and APPE can use transparency, so a RIP using APPE has no need to "flatten" in the same sense that PostScript does.

"developed a "gut feeling"" - how funny, but not really, so nothings changed in all these years then, I wonder if anyone with more experience of the APPE would know if it can be trusted to flatten 'live transparency' ??

I am not going to make a blanket statement that APPE is perfect in all situations as a RIP setting and that there may be no reason to use PostScript, nor am I going to say that one should use PostScript and to ignore APPE. There are reasons that RIPs have both settings. There are so many settings and variables in RIPs, so I am unsure if my RIP will work the same as your RIP, even if they both use APPE. The same is true for PostScript, different RIPs can give different results - even if they both licence the same PS technology from Adobe.

I would not term this as "flatten" when it comes to APPE (see above, however this may be semantics). If you are asking that if one should blindly trust APPE to correctly image any given PDF - then the day you blindly trust any RIP without double checking will likely be the day that something goes wrong and your blind trust is lost.


Stephen Marsh

 

[imagesetting]

Tim, I assume you accept PDF's from outside your organisation ?? ie from clients, do you know how your clients create their PDF's and from what Apps ie save as PDF - or Postscript then Distill ?

Stephen, I understand PS needs to flatten transparency - from what I can see PS removes 'live transparency' and breaks objects up ready for preprocessing ... but if a PDF is submitted and we Flatten Transparency using say Acrobats Flattening command - the file still needs to be Flattened correctly by Postscripting again (assuming our RIP cant handle live transparency) ??
Saying all that we still get odd results from some files when printing PS straight from the App, say Indesign.
I've read Adobe's guides Print Production Guides, but is there any reading you would recommend beyond those articles (I've read the Postscript LVL2 book, very dry - to be avoided unless you like a dull read).

 

[Stephen Marsh]

Tim, I assume you accept PDF's from outside your organisation ?? ie from clients, do you know how your clients create their PDF's and from what Apps ie save as PDF - or Postscript then Distill ?

Most of the time this can be found by looking at the Document Properties/Description tab.

Stephen, I understand PS needs to flatten transparency - from what I can see PS removes 'live transparency' and breaks objects up ready for preprocessing ...

Yes, these are referred to as "atomic regions", if I recall correctly.

but if a PDF is submitted and we Flatten Transparency using say Acrobats Flattening command - the file still needs to be Flattened correctly by Postscripting again (assuming our RIP cant handle live transparency) ??

No, whether the file is flattened during printing/export to PostScript or in Acrobat transparency flattener - the file is still "flattened". View both types of flattened PDF in the Acrobat transparency flattener, the result will indicate that there is no transparency in the file.

If the file has been flattened, then the PostScript stream will simply send down the more complex "atomic regions, vectors, rasters, stacking order etc" to the RIP.

You may settle on two general RIP settings when you get your APPE RIP. One automated workflow or hot folder/virtual printer would use APPE and you would send all PDF files at version 1.4 or higher to this APPE setting. This may be whether they actually contain transparency or not (a one size fits all approach based on the fact that the file may potentially contain transparency).

PDF files at version 1.3 may simply be sent to a workflow/hot folder/virtual printer that uses CPSI... or perhaps you will decide that APPE can/should do it all.

Or perhaps you will settle on a workflow at the RIP that "downgrades" all incoming PDF to version 1.3.

There are many possibilities!


Regards,

Stephen Marsh

 

[imagesetting]

Yes they are 'Atomic Regions'

So its up to the RIP to interpret and plot all those atomic regions correctly.
I hope a newer version RIP will help, even flattening files by creating Postscript still doesn't result in correct output at the moment - hence our need to occasionally rasterise before it hits the RIP.

 

[michaelejahn]

Question

I didn't know you could save out as a TIFF from Acrobat, would that Flatten correctly ??

Answer

It will do a far better job then opening a PDF in Photoshop.

 

[M. R. Horton]

... even flattening files by creating Postscript still doesn't result in correct output at the moment - hence our need to occasionally rasterise before it hits the RIP.

Exhibition Display Services, Cromalin Proofing & Prepress

I don't disagree with the advice you are currently getting, but could you post example images of "correct" and "incorrect" output? That might help others to quickly identify the same problem and apply the solution(s) given here.