PDF Colors changing after Distilling

printing656

Well-known member
Hello-
We receive hundreds of PDF files a month containing thousands of PDF pages with variable text on them. In order to deflate the PDF and reduce it's size (it's bloated with extra postscript), we have to run each PDF through Distiller.

In the process, Distiller is changing the colors, even when using the color settings of 'Leave Color Unchanged' or Convert all Color to RGB, Distiller still changes them. The native PDF contains RGB pure black and Distiller produces a rich black. Does anyone have any advice on specific settings that stop this from happening?
thank you
 

leonardr

Well-known member
There are a LOT of misconceptions or outright errors in this, so let's work through those first...


We receive hundreds of PDF files a month containing thousands of PDF pages with variable text on them.
PDF doesn't support variable text. Do you mean something such as editable/fillable form fields?

In order to deflate the PDF and reduce it's size (it's bloated with extra postscript),
There is NO POSTSCRIPT in a PDF file. So whatever you think is the increase has nothing to do with Postscript.

we have to run each PDF through Distiller.
Distiller doesn't except PDF as input. It takes Postscript (or EPS) in and outputs PDF.

So can you please give us an accurate description of what you are doing since we can't make any sense of this previous set of statements :(.
 

printing656

Well-known member
Leonardr-
By 'variable text' I mean more simply, variable data, meaning no single page is like the other because every one has different invoice data and/or marketing pictures on the page.

Regarding bloated PDF, I mean each invoice in the PDF, prior to being sent to us, was a standalone PDF that was then concatenated together prior to transmission to us. My understanding is that PDFs combined this way are not optimized and when we print to our postscript printers, they produce files that are 4 times larger than they should be, or in other words, produce bloated postscript files.

Regarding running each PDF through Distiller and your response...
By using the Adobe PDF printer you can print PDF files to PDF using the settings which are set in Distiller. The Acrobat icon appears in the system tray and it then says Distilling to PDF. This is done to remove the 'bloated PDF data' like header and trailer information which will then later in the workflow, produce postscript files 4 times smaller (smaller as in 1 gig instead of 4 gig).

Thanks for questioning and responding. I've been dealing with this issue for so long I forget the connecting details.
 

Stephen Marsh

Well-known member
Acrobat Pro - Optimized PDF can remove a lot of crud from a PDF to reduce it's file size* without the need to "refry" the PDF through PostScript.

*I am not sure if the PS print data from such a file will be cleaner, however the PDF will be. Even if one does not flatten, resample or convert colours or change PDF version levels, there can often be significant file size reductions.

What do you mean by "RGB Pure Black", something like 122r122g122b (R=G=B), a pure neutral? If you have a "Rich Black" in the final converted file, do you mean that the RGB is now CMYK, or do you mean that the RGB is no longer neutral R=G=B?


Stephen Marsh
 
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printing656

Well-known member
Stephen-
We've tried some of the various Optimizing options, but they don't correct the sizing issue. I'm not saying we couldn't have missed something, I'm just saying everything we looked at didn't seem to have nearly as large of impact as 'refrying' does.

Regarding RGB, yes, I mean that the PDF coming to us is in RGB and the blacks are 122,122,122, or 0,0,0 or all 3 values are the same. EFI products interpret these types of color as black or a shade of black, not using any other colors to produce black. By Rich black I mean that now the RGB is 122,125,125 or something like that for example. So now the printer uses all 4 colors to produce the black, which is not good for color toner usage.
 

rich apollo

Well-known member
There are too many variables here to give any definitive answers. I have to agree with Leonard, refrying your PDFs this way seems less than optimal.

I'd love to run a test with you to see if I can get you similar (or acceptable) results without refrying.

You can fix the RGB black with a PitStop action.
 

leonardr

Well-known member
Leonardr-
By 'variable text' I mean more simply, variable data, meaning no single page is like the other because every one has different invoice data and/or marketing pictures on the page.
But do they use the same font? I suspect the answer is yes, but can you confirm?

Also, do you know how these pages are created? What tool/program and with what PDF creation settings?


Regarding bloated PDF, I mean each invoice in the PDF, prior to being sent to us, was a standalone PDF that was then concatenated together prior to transmission to us. My understanding is that PDFs combined this way are not optimized and when we print to our postscript printers, they produce files that are 4 times larger than they should be, or in other words, produce bloated postscript files.
Excellent - that's quite helpful!

My ASSUMPTION (since I can't see the specific files, but have seen this situation before) is that whatever tool was used to combine the individual PDFs together into a single PDF was (a) NOT Adobe Acrobat and (b) therefore didn't do font optimization during the combine process. When combining pages/files, Acrobat will look to see if the fonts used across the documents are the same and if so they will be merged/optimized - instead of what simple merging programs do which is to leave multiple copies (and thus bloat the file).


By using the Adobe PDF printer you can print PDF files to PDF using the settings which are set in Distiller.
You can, but we don't recommend this process of refrying PDFs as it throws away a LOT of PDF data (that can't be replicated in Postscript).

This is done to remove the 'bloated PDF data' like header and trailer information which will then later in the workflow, produce postscript files 4 times smaller (smaller as in 1 gig instead of 4 gig).
A PDF MUST have a header and a trailer - or it's not a PDF. So that's not what is being removed.

My ASSUMPTION is that what is happening is font optimization, since refrying includes rewriting the font data for the entire document (which is one of those reasons why refrying is a bad idea!).
 

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