Issues with PDF uploaded to POD site

[caelia]

Hi, all! I have designed a calendar that I want to have printed by gelato . com, a leading print-on-demand (POD) company. This message is long, so I am dividing it into sections as follows:

• File & Environment Info
• Issue #1: (possibly spurious) warning about overprinted text
• Issue #2: image resolution warning
• Issue #3: one color appears wrong in online preview

If your time is limited, I am very concerned about Issue #1, much less so about the others. If you want to inspect the Scribus file and the PDF output, please use the Google Drive links at the bottom.

So, here we go:

File/Environment Info

• Scribus 1.5.8 on Arch Linux
• In Document Profile: RGB Images & Colors are set to sRGB IEC61966-2.1; CMYK Images & Colors, and Printer are set to Coated GRACoL 2006 (ISO 12647-2:2004)
• Export settings: PDF/X-4, max. image resolution - 300, all fonts subsetted, output intent - GRACol 2006 (ISO 12647-2:2004)
• Objects in file comprise text, solid-colored rectangles, raster images, and one SVG image.
• All colors used in the file are CMYK
• All raster images use the GIMP builtin sRGB profile.

BTW, Gelato's guidelines for print-ready files specify PDF/X-4, GRACoL 2006, sRGB images, and image resolution from 150-300dpi. So AFAICT my PDF is fully conformant to those guidelines.


Issue #1

When I upload the file, I get a warning message as follows:

   Black text (DeviceCMYK) is set to overprint but OPM is off (1)

   If OPM is off for a DeviceCMYK object, it will only overprint
   spot colors. If OPM is on, it may overprint other objects, but
   only with "unused" color channels (0% tint value). OPM is also
   referred to as "Illustrator overprint mode".

First of all, I don't understand *exactly* what this means. Does "black" literally mean only pure black, or does it refer to any color with a black component > 0? Or something else? I know you may not be able to definitively interpret someone else's error message, but perhaps you have an educated guess (BTW, I've contacted Gelato support about this, and I've waited more than 12 hours for an email response, and I haven't heard from them ...)?

Also, I am familiar with the concepts of overprint and knockout, but don't have enough practical experience to know how this issue may affect the final product.

But beyond that, the warning message is strange for several reasons:

• The issue was detected on only one page. The page in question is a date grid page (remember, this is a calendar), which contains colored rectangles and text objects - no images. There are 11 other pages with the same types of objects, and all text objects have been copied and pasted in multiple locations throughout the file, with the content edited as needed. Each page uses different colors for text and some of the colored rectangles, and of course the exact positions of the various objects vary according to the month. But again, every page has similar objects, and there are no objects that appear on only one page. So if there is a problem on one page, it seems the same problem should occur on 11 other pages.
• There is very little text that is pure black, and as far as I can tell, all of that text is over a white background. There are some text objects in several dark colors (but not pure black) that are positioned over colored backgrounds.
• AFAICT, no objects in the file are set to Overprint. At least on my system, Knockout is the default, and I did not intentionally change that setting anywhere.

In the event I don't hear back from Gelato (which seems likely at this point), I need to make an educated guess how to deal with this, so any thoughts are appreciated. I don't think another POD provider is an option, because AFAIK Gelato is the only company that will print a calendars with every page customized.

Issue #2

There is a second warning message stating that an image has low resolution. That would be the background image on the front cover. All other images are over 300dpi, and downsampled to 300dpi in the output (that's what the Maximum Image Resolution setting does, isn't it?). The image in question is an abstract background pattern with blurry edges, and it's at 200dpi, so I think that should be fine, right?

Issue #3

There is one text object on the front cover that in the Scribus file is light blue. The layer containing this object (and no other objects) is set to Hard Light blend mode with 80% opacity. It is over a dark red background, so it appears as bluish purple. When I view the PDF on my desktop, it looks almost exactly as designed, but in Gelato's online preview (whose accuracy is unknown), it appears as kind of a dull salmon pink. It's an acceptable color, but I'd like to fix it if possible. Any suggestions?

Thanks for your attention to this really long post, and any suggestions you can offer!

File links

Scribus file
PDF

[PatJr]

this is beyond my level
I tried to look at the scribus doc but I was missing fonts, color profiles, images, ...

when I have used print services I found that removing all transparencies I had better luck with the outcome

instead of over print maybe using knockout would work around that and if it's black, use a rich black 20,20,20,100

[caelia]

instead of over print maybe using knockout would work around that

You must have missed the part where I wrote

AFAICT, no objects in the file are set to Overprint. At least on my system, Knockout is the default, and I did not intentionally change that setting anywhere.

IOW, everything is already set to knockout.

Oh well, thanks anyway!

[AdmFubar]

I think the issue might be the PDF/X4 using in scribus. It depends on what version was implemented, and what version your print shop requires.

check here for some infor on PDF/X-* features
https://graphicdesign.stackexchange.com/questions/55365/why-are-pdf-x-files-better-than-standard-pdfs

The holidays seem to be in black text, could this be the source of the errors?

I'd check with your print shop to get more details on the specs of the pdf/x4 they need.

[caelia]

I think the issue might be the PDF/X4 using in scribus. It depends on what version was implemented, and what version your print shop requires.

check here for some infor on PDF/X-* features
https://graphicdesign.stackexchange.com/questions/55365/why-are-pdf-x-files-better-than-standard-pdfs

Thank you! I'll check that out.

The holidays seem to be in black text, could this be the source of the errors?

Maybe? But they're not pure black. The actual color is C 0, M .45, Y .45, K .75. Which is why I am wondering what the precise definition of "black text" is in the warning message. Of course, none of us here know that for sure.

Oh, also, those objects are definitely not set to overprint. At least, not in the Scribus file, and not in the obvious way in the PDF (see my update message following this).

I'd check with your print shop to get more details on the specs of the pdf/x4 they need.

Yes, well ... I am trying to get some information from them. In fact, they're looking at my PDF, so hopefully they will have some answers for me. But this is a problem in dealing with an online POD company. If I were printing a batch of these at my own expense, I'd definitely use a local print shop, and I could work out all the issues face to face. But in this situation, I'm lucky they are even willing to investigate.

Thanks for your input!

[caelia]

UPDATE: I remembered some things.

Specifically, I remembered that Scribus files are XML, and I could find out which, if any, objects were set to overprint by examining the text of the file.

I also remembered that I know *a bit* about the PDF file format (because I was planning to program a PDF generation library a while back), and have a copy of the Adobe PDF Reference (6th edition) on my bookshelf.

So, I found out:

The Scribus file format has a 'doOverprint' attribute (AHEM, undocumented, but I discovered it by means of a minimal test file). So if an object is set to overprint, it will have 'doOverprint="1"' in the file. If the object is set to knockout, 'doOverprint' is absent (or maybe has a value of 0?).

The string 'doOverprint' does not occur anywhere in my Scribus file.

In a PDF file, overprinting is indicated by the operators '/OP true' and '/op true'. I generated a test PDF with one object set to overprint, and found that both '/OP true' and '/op true' were present. Neither of these strings occurs in the PDF that I uploaded to the printer. Though PDF is a very complex file format, and I only have a very basic understanding of it, so I can't be completely sure, but it appears that nothing in that PDF is set to overprint.

Also, to reiterate a point I've already stated, as far as I know my file does not contain any pure black text over a colored background.

My best guess at this point is that the warning message is not precisely describing the real issue. So I'm hoping the printing company can clarify things. But I'm still interested in what folks here have to say.