Why are PDF/X files better than "standard" PDFs?

Question

I have a friend who is also a graphic designer, has little experience in prepress, but has a nice portfolio and seems to have a good knowledge of using the Adobe products. I can't dismiss his opinion on Adobe files.

The other day, he started arguing that a PDF/x was better for all kinds of print-ready files no matter what. As a designer with a lot of prepress experience, I simply prepare my print-ready PDF to be "standard" PDF and I have never encountered any weird issues with transparency or anything "scary" on the PDFs (eg. fragmented images or white squares around masks).

I send my files all around the world to be ripped on new and old systems; they need to be fully compatible as I cannot always approve the proof myself.

I already know about the basics to get the maximum quality for a print layout.

I'm skeptical about the value of using PDF/x if:

1. My pictures are all done in Photoshop and flattened (eps)
2. My vectors are from Illustrator without any transparency or blending modes. Texts are vectorized (eps)
3. Everything is imported in an InDesign or QuarkXpress file, again without using any shadow or transparency in these two programs.
4. Finally, my PDF gets optimized in Adobe Acrobat Pro and my files are rarely larger than 5MB (for files of 90MB+ when not optimized)
5. I usually need a web version as well of these PDFs with bookmarks and hyperlinks, and they need to be around 500-700kb

Am I missing something about PDF/x? What would be the benefits for me to use a PDF/x instead of a "normal" PDF for print-ready and digital web design? Is there any reason why I should switch to PDF/x or is it only for designers who use InDesign and Illustrator with transparency and blending effects?

I thought PDF/x was mainly good for layout using transparency and fancy effects but maybe I'm a dinosaur with my boring standard PDF. My designs really don't suffer from my way of using this software and I still use transparency and effects but rarely in vector mode. I did some research online but usually they only mention how these PDF/x files are fully compatible but it looks like they only refer to the new RIP.

I'd like an answer a bit more concrete than just "because it's better."

Answer 1

PDF is a complex standard that includes a huge number of features, and the kitchen sink on top of that. Not all of those features are conducive to print production (for example, hyperlinks).

PDF/X requires that your document is prepared for print. That is:

• All fonts are embedded in the file

• All images are in CMYK or in spot color mode, OR contain color profile info so that the CMYK conversion is defined in the document.

  • In effect output intent needs to be specified
  • Different PDF/X standards have slightly different restrictions here.
• Transparency needs to be flattened
• Some newer PDF/X files can have OPI for external graphics etc that can benefit printer memory consumption
• and so on.

The standard also says that you may not use certain features. This makes sense as the file format is then less likely to cause problems with compatibility.

There are also features in web PDF files that are a bit problematic for print, such as image compression sizes. The press is not so concerned by your file size.

Why is PDF/X better?

There is a smaller likelihood that something will go wrong. That's it.

If you sent for example RGB images without color profiles or output intent, you would have the press guessing. Every time the manufacturing plant infers something, there is a rather big likelihood that something will go wrong (thinking is not their job).

Think of PDF/x like a pre-processor mechanism that tries to force you to do all the best practices. Nothing really says a non-PDF/X file cannot print well, it's just that a PDF/X file is less likely to have problems.

Answer 2

First.. there is no such thing as a "standard" PDF. What does that even mean? What is a "standard" pdf???

If anything, there are "PDF Standards" which is the PDF/X format.

PDF/X-1a comes with some valuable restrictions on the data it can contain.

• All color must be greyscale, CMYK, or Spot colors. RGB data is not allowed in a PDF/X-1a file.
• All fonts must be embedded, this ensures there are no font issues.
• Embedded images with individual ICC profiles are not permitted. One profile is used for the entire document. This ensures color remains consistent throughout the PDF.
• PDF/X-1a files can't contain javascript or forms.
• PDF/X-1a files can't include interactive items such as video, audio, non-printable annotations, markup, etc.
• PDF/X-1a files contain additional markers for the media box, trim box, and bleed box (if the bleed was included). This ensures proper sizes during production.
• OPI or low resolution "for position only" image data is not allowed in a PDF/X-1a file. This prevents undue compression or the existence of incorrect images.
• PDF/X is regulated by the International Standards Organization (IOS) and is designed to remain consistent without any oversight from any one specific vendor.

(Note this references the most commonly preferred format for print providers, PDF/X-1a. There are other formats for PDF/X such as PDF/X-3 or PDF/X-4 which alter restrictions a bit. However, PDF/X-1a is still the most used PDF format for print production.)

All these items ensure that print production is smooth without any problems. Can you use other PDF job options to create a PDF that can be reproduced? Sure you can. The entire purpose of PDF/X files is to ensure there's no issue during production. That does not mean one cares if there are or are not issues.

If you don't care that a photo make be reproduced with poor color, If you don't care that a font is substituted, if you don't care that some embedded javascript and form data chokes the imagesetter, if you don't care that the piece is improperly trimmed, if you don't care that the bleed was not used.... then it's fine to use some other PDF settings. PDF/X is designed to prevent unknowledgable users from creating issues they are unaware of.

Think of PDF/X like a "spell checker". Do you use a spell checker? Isn't it designed to help prevent errors? Are you forced to use a spell checker? Heck no. Will you regret not using it when someone points out an error, probably yes. Well that's all PDF/X is designed to do... prevent errors. Why would you not use it for print production?

This question is flawed, it assumes the design is always lacking any transparency which is, quite honestly, false in todays world. Almost all designs today contain some form of transparency even if very minute. And all designs contain fonts, ensuring they are embedded is always best practice. Few are using EPS files for images from Photoshop. Most often they are .psd or .tif files (there aren't many QuarkXpress users left that use EPS for raster images - that's a remnant of 15 years ago). And many new designers today may even try and use jpg or png images for print production. PDF/X corrects that usage.

I think you are grasping at straws to be honest. Sure you can create a PDF that will reproduce just fine, if you know how to create it, what to avoid, what to not do... but you are assuming everyone has that same knowledge, which they don't.

Answer 3

1. It is never a good idea to outline text, as you loose hinting and in InDesign you loose automatic numbers, bullets, rulers, text frames, references and many more problems. The only correct solution is to embed fonts.
2. If a font distributer does not allow embedding normally he does neither allow outlining for print purposes. The only correct solution is to use a font which allows embedding.
3. InDesign, Illustrator and Photoshop use the very same Color Engine. It is not even installed twice on the same computer. If you have the same settings you get the same result if you convert an image in Photoshop, or print from a RGB in Photoshop a CMYK proof or convert the image later when you export a PDF from InDesign or Illustrator or later when you print with Acrobat using the Adobe PDF Print Engine 2, APPE2. Therefore for more flexibility you will use RGB images only for print in InDesign as it allows you to use the same file for different print conditions and even for cross publishing for print or for screen.
4. Any conversion causes a loss of information. When you convert from RGB to CMYK you loose information and also quality. Many digital printer require input in form of RGB. If they get CMYK images they have to convert them before processing internally to RGB, so when it comes to bring CMYK to such a digital printer you can expect a conversion flow from RGB to CMYK in Photoshop, from CMYK to a different CMYK in InDesign to PDF, from CMYK to RGB internal in the printer and from RGB to CMYK in the printer again, it looks technically this way: RGB > LAB > CMYK > LAB > CMYK > LAB > RGB > CMYK output. The LAB is an intermediate conversion which will always take place. If you remain in RGB you have this: RGB > LAB > RGB output. Less loss. Therefor use PDFs which don't convert color spaces, like PDF/X-3 or PDF/X-4.
5. When it comes to transparency the flattening should be done as late as possible. With the flattening comes always a slicing of images and also a conversion to a different color or colorspace. You see those slicing lines in Acrobat only, if you turn on antialiasing for vectors in Acrobat's preferences. BUT, but but but, even if they are normally not seen in print output, there are a lot of cases you will see them: If you convert a file to a different file (type) and color space in the same step, as it happens, when you have to export such a file, e.g. you want to export an INDD file to an EPUB, screen PDF, JPG, etc. You will see those slices! The only resolution is to use not flattened material as it is reach PDF, like PDF/X-4. This also prohibits all kind of flattened files like EPS, PDF/X-1a and PDF/X-3.
6. When it comes to color management, EPS does not support color management. InDesign's ink manager is bypassed when a PDF is created with EPS files and using print and Distiller. Therefore: Don't use EPS, don't use Distiller.
7. Some user might need to turn on and off different layers of a PDF when they place them in InDesign, maybe different language versions. Only the latest PDF/X-4 specification allows that. Therefore use PDF/X-4.

There are many reasons more, why someone will require PDF/X-4 for any modern workflow, specially in combination with InDesign, Illustrator, Photoshop and Acrobat. So it is correct to use for file exchange PDF/X-4 only. No EPS, no PDF/X-1a no PDF/X-4. But the final output for a specific printer is a different thing. You have to deliver what they need. Even if you have placed PDF/X-4 only in InDesign or Illustrator you can still export a CMYK PDF/X-1a or a mixed color space PDF/X-3 or even an EPS file. Using a PDF/X-4 gives you a maximum on flexibility with the minimum of loss of quality.