Pros and cons of exporting PDFs as PDF/X-4 for print?

Phaedra PDF exporting is one very deep subject, especially when using Affinity Apps. Affinity uses PDF-Lib, which is a free, open source library. It's good, but not perfect.

Affinity has various "hierarchy rules" which complicate the matter. If you have placed PDF content in your file, your final PDF export must utilize a PDF version that is as high or higher than any placed PDF content. So if you have some placed PDF content that uses PDF v1.6, you need to export using a PDF v1.6 preset or higher. Also, PDF/X and non-PDF/X placed content don't play well together in the same document when exporting to PDF. It's complicated, and you will need to do some trial and error, and check your exported PDF files carefully.

I have found that PDF v1.7 is generally a good choice when exporting. It is the highest PDF version in Affinity, so it handles all placed PDF versions. This, of course, supports transparency. PDF/X-4 works well as long as you place ONLY PDF/X based files inside of your Publisher or Designer document. Affinity has a PDF/X-1a:2003 preset, which uses PDF v1.4 and allows transparency. Affinity does not support the original PDF v1.3 export (flattened with no transparency), so printers that demand a PDF/X-1a:2001 file that is flattened may not accept your file. Speaking of transparency, Affinity does not provide a CMYK Transparency Blend Space option, so RGB Transparency Blend Space is always used, which can sometimes result in color and density shifts when exporting to PDF where you have transparency.

There are hundreds of posts on this subject on the old Affinity Forum, which at this point is still fully searchable. If you plan to send jobs to a Press, or to a picky RIP, it's a very good idea to have a good PDF analysis/editing tool, such as Acrobat Pro, Callas PDF Toolbox, etc. They will allow you to find, analyze and fix problems in the exported PDF.

It's way more complicated than it should be. You just need to check files carefully if sending to Press. Hope this helps some.

Ask your print shop if they support PDF/X-4. If they do, usually all should be good. At least in Europe…

Quote from Phaedra

When is PDF/X-4 the better choice?

• If the layout document contains colors/color spaces beyond CMYK or spot colors, such as RGB images or certain blend modes, adjustments, or effects that require conversion to a CMYK colour profile that is unknown or unavailable for PDF export.

• Accordingly, if you want to avoid flattening (rasterization) and retain certain layers and transparencies in the exported PDF to reduce the need for extra colour conversions. For example, if you don't know or use the color profile required for the printing process, e.g., for a specific printing medium (paper, foil, etc.).

• If the output medium requires pure vector objects, e.g. for cutting (vinyl plotter), which could be rasterized during X-1 export.

• If you want to enable later editing of certain objects in the PDF, e.g., layers that would be flattened in an export as X-1.

Quote from Phaedra

Can it cause compatibility issues with some print providers?
Do most printers today reliably process PDF/X-4 files?

• Yes, problems can arise if a print service provider (its prepress process/RIP) cannot process PDF versions beyond PDF 1.3.
• Not all print service providers can or want to process PDF 1.4 or higher, with or without absolute reliability.

Quote from ldina

Speaking of transparency, Affinity does not provide a CMYK Transparency Blend Space option, so RGB Transparency Blend Space is always used, which can sometimes result in color and density shifts when exporting to PDF where you have transparency.

While this export option is indeed missing, Affinity doesn't always (exclusively) use an RGB blend space. In particular when exporting to PDF/X, for certain circumstances the blend space may match the colour space selected for PDF export and thus be CMYK … which doesn't exactly make selecting the right or even best export options easier. – However, in Affinity, it can be useful in certain circumstances, even for X-4 export, to activate the export option "Convert image colour spaces", though it's not activated for the default X-4 preset.