Somebody asked me recently what the difference is between PDF/X-1a (first published in 2001) and PDF/X-4 (published in 2010). I thought this might also be interesting to a wider audience.
Both are ISO standards that deliberately restrict some aspects of what you can put into a PDF file in order to make them more reliable for delivery of jobs for professional print. But the two standards address different needs/desires:
PDF/X-1a content must all have been transformed into CMYK (optionally plus spots) already, so it puts all of the responsibility for correct separation and transparency handling onto the creation side. When it hits Harlequin, all the RIP can do is to lock in the correct overprint settings and (optionally) pre-flight the intended print output condition, as encapsulated in the output intent.
On the other hand, PDF/X-4 supports quite a few things that PDF/X-1a does not, including:
Device-independent color spaces
Live PDF transparency
Optional content (layers)
That moves a lot more of the responsibility downstream into the RIP, because it can carry unseparated colors and transparency.
Back when the earlier PDF/X standards were designed transparency handling was a bit inconsistent between RIPs, and color management was an inaccessible black art to many print service providers, which is why PDF/X-1a was popular with many printers. That’s not been the case for a decade now, so PDF/X-4 will work just fine.
In other words, the choice is more down to where the participants in the exchange want the responsibility to sit than to anything technical any more.
In addition, PDF/X-4 is much more easily transitioned between different presses, and even between completely different print technologies, such as moving a job from offset or flexo to a digital press. And it can also be used much more easily for digital delivery alongside using it for print. For many people that’s enough to push the balance firmly in favour of PDF/X-4.
For further reading about PDF documents and standards:
Would you fill your brand-new Ferrari with cheap and inferior fuel? It’s a question posed by Martin Bailey in his new guide: ‘Full Speed Ahead – how to make variable data PDF files that won’t slow your digital press’. It’s an analogy he uses to explain the importance of putting well-constructed PDF files through your DFE so that they don’t disrupt the printing process and the DFE runs as efficiently as possible.
Here are Martin’s recommendations to help you avoid making jobs that delay the printing process, so you can be assured that you’ll meet your print deadline reliably and achieve your printing goals effectively:
If you’re printing work that doesn’t make use of variable data on a digital press, you’re probably producing short runs. If you weren’t, you’d be more likely to choose an offset or flexo press instead. But “short runs” very rarely means a single copy.
Let’s assume that you’re printing, for example, 50 copies of a series of booklets, or of an imposed form of labels. In this case the DFE on your digital press only needs to RIP each PDF page once.
To continue the example, let’s assume that you’re printing on a press that can produce 100 pages per minute (or the equivalent area for labels etc.). If all your jobs are 50 copies long, you therefore need to RIP jobs at only two pages per minute (100ppm/50 copies). Once a job is fully RIPped and the copies are running on press you have plenty of time to get the next job prepared before the current one clears the press.
But VDP jobs place additional demands on the processing power available in a DFE because most pages are different to every other page and must therefore each be RIPped separately. If you’re printing at 100 pages per minute the DFE must RIP at 100 pages per minute; fifty times faster than it needed to process for fifty copies of a static job.
Each minor inefficiency in a VDP job will often only add between a few milliseconds and a second or two to the processing of each page, but those times need to be multiplied up by the number of pages in the job. An individual delay of half a second on every page of a 10,000-page job adds up to around an hour and a half for the whole job. For a really big job of a million pages it only takes an extra tenth of a second per page to add 24 hours to the total processing time.
If you’re printing at 120ppm the DFE must process each page in an average of half a second or less to keep up with the press. The fastest continuous feed inkjet presses at the time of writing are capable of printing an area equivalent to over 13,000 pages per minute, which means each page must be processed in just over 4ms. It doesn’t take much of a slow-down to start impacting throughput.
If you’re involved in this kind of calculation you may find the digital press data rate calculator at https://blog.globalgraphics.com/tag/data-rate/ useful:
This extra load has led DFE builders to develop a variety of optimizations. Most of these work by reducing the amount of data that must be RIPped. But even with those optimizations a complex VDP job typically requires significantly more processing power than a ‘static’ job where every copy is the same.
The amount of processing required to prepare a PDF file for print in a DFE can vary hugely without affecting the visual appearance of the printed result, depending on how it is constructed.
Poorly constructed PDF files can therefore impact a print service provider in one or both of two ways:
Output is not achieved at engine speed, reducing return on investment (ROI) because fewer jobs can be produced per shift. In extreme cases when printing on a continuous feed (web-fed) press a failure to deliver rasters for printing fast enough can also lead to media wastage and may confuse in-line or near-line finishing.
In order to compensate for jobs that take longer to process in the DFE, press vendors often provide more hardware to expand the processing capability, increasing the bill of materials, and therefore the capital cost of the DFE.
Once the press is installed and running the production manager will usually calculate and tune their understanding of how many jobs of what type can be printed in a shift. Customer services representatives work to ensure that customer expectations are set appropriately, and the company falls into a regular pattern. Most jobs are quoted on an acceptable turn-round time and delivered on schedule.
Depending on how many presses the print site has, and how they are connected to one or more DFEs this may lead to a press sitting idle, waiting for pages to print. It may also delay other jobs in the queue or mean that they must be moved to a different press. Moving jobs at the last minute may not be easy if the presses available are not identical. Different presses may require different print streams or imposition and there may be limitations on stock availability, etc.
Many jobs have tight deadlines on delivery schedules; they may need to be ready for a specific time, with penalties for late delivery, or the potential for reduced return for the marketing department behind a direct mail campaign. Brand owners may be ordering labels or cartons on a just in time (JIT) plan, and there may be consequences for late delivery ranging from an annoyed customer to penalty clauses being invoked.
Those problems for the print service provider percolate upstream to brand owners and other groups commissioning digital print. Producing an inefficiently constructed PDF file will increase the risk that your job will not be delivered by the expected time.
You shouldn’t take these recommendations as suggesting that the DFE on any press is inadequate. Think of it as the equivalent of a suggestion that you should not fill your brand-new Ferrari with cheap and inferior fuel!
The above is an excerpt from Full Speed Ahead: how to make variable data PDF files that won’t slow your digital press. The guide is designed to help you avoid making jobs that disrupt and delay the printing process, increasing the probability of everyone involved in delivering the printed piece; hitting their deadlines reliably and achieving their goals effectively.
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About the author:
Martin Bailey first joined what has now become Global Graphics Software in the early nineties, and has worked in customer support, development and product management for the Harlequin RIP as well as becoming the company’s Chief Technology Officer. During that time he’s also been actively involved in a number of print-related standards activities, including chairing CIP4, CGATS and the ISO PDF/X committee. He’s currently the primary UK expert to the ISO committees maintaining and developing PDF and PDF/VT.
We’ve recently released Mako™ 5.0, the latest edition of Global Graphics Software’s digital document SDK. Mako 5.0 earns its major version increment with an upgrade to its internal RIP, new features and a reworked API to simplify implementation. Much requested by Mako customers, Mako 5.0 is the first version to preview C# as a coding alternative to C++ and opens the possibility to support other programming languages in future versions.
Mako 5.0 enables PostScript® (including EPS) files to be read directly, extending the PDL (page description language) support in Mako that already includes PDF, XPS, PCL5 and PCL/XL. Mako can read and write all these PDLs, enabling bi-directional conversion between any of these formats.
With the update of Mako’s internal RIP has come new EDS (error diffusion screens) using algorithms such as Floyd-Steinberg and Stucki. All the screening parameters are exposed via this API, and to help define them, a Windows-based desktop tool can be downloaded from the Mako documentation site. Start with settings that match the popular algorithms and preview the monochrome or color result of your settings tweaks. Then use the settings you have chosen via a button that generates the C++ you need to paste into your code.
Mako 5.0 offers several new APIs that extend its reach into the internals of PDF. For example, it’s now possible to edit property values attached to form and image XObjects. Why is this useful? In PDF, developers can put extra key-value pairs into PDF XObject dictionaries. This is often used to store in application-specific data, as well as for things like variable data tags. This development has led to a more generalized approach to examining and modifying hard-to-reach PDF objects. As ever, well-commented sample code is provided to show exactly how the new APIs work and could be applied in your application.
Finally, we took the opportunity with Mako 5.0 to make changes aimed at making the APIs more consistent in their naming, behavior or return types. Developers new to Mako will be unaware of these changes, but existing code written for Mako 4.x may require minor refactoring to work with Mako 5.0. Our support engineers are ready to assist Mako customers with any questions they have.
Working with a Mako customer recently, I showed him how to code a utility to extract data from a stack of PDF invoices to populate a spreadsheet. I suppose you could describe it as reverse database publishing. This customer had originally licensed Mako to convert XPS to PDF, and later used it to generate CMYK bitmaps of the pages, i.e. using it as a RIP (raster image processor).
With this additional application of Mako, the customer observed that Mako was “like a Swiss Army knife” as it offered so many tools in one – converting, rendering, extracting, combining and processing, of pages and the components that made them up. And doing it not just for PDF but for XPS, PCL and PostScript® too. His description struck a chord with me as it seemed very appropriate. Mako does indeed offer a wide range of capabilities for processing print job formats. It’s not the fastest or feature-richest of the RIPs from Global Graphics Software – that would be Harlequin®. Or the most sophisticated and performant of screening tools – that would be ScreenPro™. But Mako can do both of those things very competently, and much more besides.
For example, we have used Mako to create a Windows desktop app to edit a PDF in ways relevant to production print workflows, such as changing spot colors or converting them to process colors. All the viewing and editing operations are implemented with Mako API calls. That fact alone emphasizes the wide range of applications to which Mako can be put, and I think, fully justifying that “Swiss Army knife” moniker.
Using Mako to pre-process PDFs for print workflows follows quite naturally. With its built-in RIP, Mako has exceptional capability to deal with fonts, color, transparency and graphic complexity to suit the most demanding of production requirements.
What is less obvious is Mako’s value to enterprise print management (EPM). Complementing Mako’s support for PDF and XPS is the ability to convert from (and to) PCL5 and PCL/XL. Besides conversion, Mako can also render such documents, for example to create a thumbnail of a PCL job so that a user can more easily identify the correct document to print or move it to the next stage in a managed process. Mako’s document object model (DOM) architecture allows content to be extracted for record-keeping purposes or be added to – a watermark or barcode, for example.
The ability to look inside a document, irrespective of the format of the original, has brought Mako to the attention of electronic document and records management system (EDRMS) vendors, seeking to add value to their data extraction, search and categorization processes. Being able to treat different formats of document in the same way simplifies development and improves process efficiency.
Mako’s ability to analyse page layout and extract text in the correct reading order, or to interpret and update document metadata, is a valuable tool to developers of EDRMS solutions. In the face of GDPR (General Data Protection Regulation) and sector-specific regulations, the need for such solutions is clear. And as many of those documents are destined to be printed at some point in their lifecycle, they exist as discrete, paginated digital documents for which Mako is the key to unlocking their business value.
Product manager David Stevenson provides an update on the latest release of Mako:
We’ve just released Mako version 4.6 and I’m pleased to let you know that new in this release is support for PCL5 input, adding to the PCL/XL support already available. Aimed primarily at the enterprise print market, this capability makes it possible to convert to and from PDF & XPS formats and to render thumbnails for preview purposes.
This latest release will also be of interest to our prepress customers: we’ve improved overall performance and added new, fast render-to-buffer capability, in monochrome and color.
Finally, there is also new and improved support for PDF-named destinations, document metadata and more.