What is PDF/X?

The PDF/X standard has been available to the printing industry for more than 20 years and is very popular. The regular PDF standard is certainly still relevant. But the PDF/X format has already found its place in the software and processes of the printing industry. In this article, we will get acquainted with the PDF/X format, discuss its types, and find out what purposes this file format is needed for.

What is PDF/X?

PDF/X was the first ISO standard based on PDF technology. A subset of the PDF specification, PDF/X was designed to enable PDF files to meet specific user needs. For example, the relevant files must be complete, i.e., self-sufficient. This requires that elements such as fonts used on a page are embedded in the document, in addition, content such as 3D graphics or videos cannot be part of a PDF/X document. Additionally, the information contained in a PDF/X document must be accurate.
The purpose of PDF/X is to facilitate the sharing of graphics, so it has a number of printing-related requirements that do not apply to standard PDF files.

PDF/X guarantees that the file will work when sent for professional printing (embedded fonts, no RGB colors, etc.).

The PDF/X document specification was created by Adobe. PDF/X files are supported by software applications available for Windows, Mac and Linux devices.

What are the different types of PDF/X?

There are various variants of the PDF/X family of standards, each of which is intended to provide a certain output.

• PDF/X-1a: The original PDF/X standard, or PDF/X-1a, requires that all material is contained in a PDF document in order to be printable. External fonts, forms, password protection, and visible annotations are not allowed in the document. There are certain requirements for PDF/X-1a, such as transparency and allowed layers. They also require that only CMYK, grayscale, or spot colors are used in printing, with no RGB or device-independent color spaces. PDF/X is designed to be exchanged, all files must be delivered in CMYK (and/or spot colors), with no RGB or color-managed data.
• PDF/X-3: Was launched in 2002 and removed numerous limitations of PDF/X-1a. It allowed the use of CMYK, grayscale, RGB, Lab, and ICC color spaces in PDF/X-3 documents. In fact, it is based on the PDF 1.3 standard with the ICC profile. Because of the adaptability and limitations it imposes on the colors used in a PDF document, it is also known as color management.
• PDF/X-4: Supports transparencies, so PDF-X/4 contains all data required for output without flattening.
• PDF/X-5: Is based on PDF/X-4 and adds reference XObjects, external n-colorant profiles, and support for external graphics for rendering purposes. Likewise, it can be used for partial exchange of print data with PDF version 1.6.

New in PDF/X-6

ISO has just recently published a new version of the PDF 2.0 standard. With the release of PDF 2.0, a new version of the PDF/X standard was also introduced. The new standard for the printing industry is called PDF/X-6 and is the successor to PDF/X-4. It contains several innovations compared to PDF/X-3, published in 2002, and PDF/X-4, published in 2008.

• PDF/X-6: ISO 15930-9:2020 – PDF files for professional printing. The most important innovation is the page output. An example: A brochure with a cover printed on coated paper and an inside printed on uncoated paper can now be exported to a single PDF file with two output conditions: PSO CoatedV3 and PSOUncoatedV3, mixed depending on pages. Previously, the file could only contain one output profile. Also new is depth compensation and embedding spectral data for faded colors according to CxF-4. As a matter of fact, this allows you to send solid colors with spectral definition instead of just writing LAB or CMYK values to the PDF. Also new is support for multicolor profiles, that is, ICC profiles with more than four color channels. The new PDF/X-6 standard is similar to PDF/X-4 in many ways.

What programs support PDF/X files?

PDF/X is a very common document format, so every regular PDF reader software supports it. You can open PDF/X files with Adobe Acrobat Reader for example. You can also open a PDF/X file directly in Google Drive without any external software.

You can learn more about PDF files and Adobe Acrobat in our previous article.

Recommendations for selecting a PDF/X Output Intent

The PDF/X “Output Intent” is usually set by the print service provider that is doing the printing. If your print service provider is unknown or unable to provide “Output Intent” recommendations, you can use one of the ICC “Output Intent” profiles listed in the table below as a starting point.

Also, all profiles are linked to the primary print destination in the organization that creates or maintains them. Сorrespondingly to select the appropriate profile, you need to know the type of printing process and paper.

CMYK PDF/X Output Intents for common printing processes and standards

Conclusion

So what is PDF/X?
The PDF/X standard was developed at the request of the graphics and printing industry to facilitate document sharing. Note that PDF/X is not a special version of PDF. It is a standard that aims to avoid the problems that can occur when exchanging documents needed for seamless graphic production, i.e., professional printing.