In the last survey I have asked for your preferred PDF format. The result is interesting. Almost forty percent prefer PDF/X-4. That’s very encouraging!
Alarming is the fact that 22% have voted for PDF/X-3. This format was orginally ment for media neutral PDF/X files using ICC source profiles. But this does not work any more with InDesign as soon as a page contains transparency. Since transparency is not allowed in PDF/X-3, InDesign must flatten transparency before exporting the PDF file. For this all objects on the page (regardless if they are involved in the transparency or not) are first color converted into the transparency blend space (document CMYK). During this operation the media neutral colors get lost (e.g. for ICCbased RGB images).
For layouts with transparency (which is very common these days) PDF/X-3 cannot be used. These was one of the reasons that we have published the ISO standard PDF/X-4 in 2008.
Most users are using PDF/X-3 not because of a media neutral workflow; 99% of all PDF/X-3 files contain only CMYK and spot colors. For this PDF/X-1a would be sufficient. Using PDF/X-3 instead of PDF/X-1a adds the danger that unwanted ICC source profiles are embedded into the document. The reason that PDF/X-3 is still so popular is due to force of habit. When PDF/X was introduced at the beginning of the millenium the only tool available in german speaking countries for the creation of PDF/X files was PDF/X-3 Inspector (Freeware):
Unfortunately PDF/X-3 Inspector could only create PDF/X-3 but not PDF/X-1a. At that time this was a wrong decision made by the sponsors of this plugin (I was one of them)!
In the meantime PDF/X-3 has lost its reason of existence! PDF/X-1a does still make sense but only for layouts which do not contain any transparency. Because transparency flattening in a layout application can destroy a PDF irreversible. Single objects are splitted into many objects. Text objects can be converted into vectors or even images. Smooth shades become ugly stipes of images. Object borders become visible (“white lines”) because of the anti-aliasing feature of Acrobat. Sometimes these lines are still visible in the printed product. Flattened PDF files get much bigger. They cannot be edited as easily anymore. There are potential problems in color management and trapping. A (badly) flattened PDF cannot be fixed even with the most expensive tools.
That’s why everybody should stay away from PDF/X-1a and PDF/X-3 and start using PDF/X-4 as soon as possible. With PDF/X-4 it’s still possible to stick to CMYK and spot colors. At PDFX-ready we have created settings, preflight profiles and recipes for the CMYK workflow with PDF/X-4.