Processing PDF without in-RIP color management

Twenty years ago it was common to find people RIPping jobs for production print with no color management. Indeed, many print service providers (PSPs), magazine publishers etc actively avoided it as being “too complicated” and “unpredictable”. You might read that as an indictment of their vendors for a lack of investment either in developing good product or in educating their users. Alternatively it might simply show that the printing companies were quite understandably risk-averse because it could be expensive if the client didn’t like the resulting color, especially in an environment like display advertising in a major magazine, or packaging for a major brand.

A decade after that more and more people (on both the buying and the printing sides) grasped the value of color management in print and were using it, but there was still a significant minority that had not managed to make the time to understand it. This is borne out by the uproar when Adobe ‘forced’ people to use color management by changing from using CMYK for the alternate color space for Pantone spots in Creative Cloud to using Lab1, and by the continuing demand for support for PDF/X‑1a, where everything has already been converted to press colorants before the PDF is made.

Now we’re in 2022, and the need for color management is accepted almost universally in print sectors that use an ink set based on CMYK. I phrased it that way because some of the industrial print space (textiles, ceramics, laminate flooring etc) have historically used many inks, but usually job-specific rather than CMYK. Some of those markets will continue to use job-specific ink sets as they transition to digital, while others would find a switch to digital extremely challenging without a concurrent switch to a color managed workflow2.

So, why am I writing this now?

It’s because I still talk to people who tell me that they don’t need to do any color management inside the RIP when processing PDF; they RIP it first and then apply color management.

I’m sorry, that just won’t work reliably and with maximum quality.

There was a time, back in the days when PDF 1.3 was the latest and greatest (which pretty much means last millennium) when a PSP could get away with this approach, because their customers were happy to define all their colors in CMYK and spots. As soon as they used anything else, including Lab or colors tagged with ICC profiles, they’d have to have some fallback to generate CMYK values from that data. It doesn’t need a full color management module (CMM), but they’d need something.

And then along came PDF 1.4, adding transparency. And transparency requires that you can convert colors between color spaces, potentially multiple times. That’s because PDF transparency includes the concept of transparency groups. Each group is one or more graphics that are blended with any graphics that are behind them in the design.

The blending depends on a number of parameters, the most obvious of which are the blend mode (Overlay, Multiply, Hard Light etc), and the blend color space. The result of rendering all graphics that are underneath the transparency group will be transformed from whatever space the RIP holds it in (often the CMYK for the output device) into the blending color space. The result of rendering all the graphics inside the transparency group itself is also transformed into the blending color space. Then the blend mode is applied, to do the actual transparency calculation, and the result is transformed back into whatever color space the RIP needs it to be in for further processing (again, often the CMYK of the output device). The blending color space is quite often sRGB, because that’s the default in a number of popular design applications.

So correct rendering of the transparency will often require color transforms between the color space in which graphics are specified (such as, maybe, an image tagged with an ECI RGB ICC profile), the blend color space (most commonly sRGB) and the output device color space (usually a specific CMYK). That’s just not possible without applying a pretty complete color management process during RIPping. And if you try to take short-cuts you’ll usually get a visually different result, sometimes very different.

Color transformation with transparency requires a full color management capability.

Even so, back in the early 2000s a PSP could avoid the need to upgrade software, process control and operator training by insisting that their customers supplied files in a format such as PDF/X-1a, which prohibited device-independent colors and transparency. But making a PDF/X-1a file from a rich design in a creative application requires a number of compromises affecting graphical elements that were originally specified in device independent colors, or which use transparency. Both risk degrading the quality of the final piece.

These days insisting on PDF/X-1a to avoid the need for color management in the RIP is no longer widely acceptable to customers3. And therefore neither is color managing after the RIPping is complete.

Your check-list is therefore:

  • Don’t use PDF/X-1a. In fact don’t use PDF/X-3 either. Both are two decades old. PDF/X-3 may allow device-independent colors, but both of them force the creation tool to flatten transparency, discard layers and a bunch of other potentially damaging procedures. It’s over ten years since PDF/X-4 was published, and that’s currently the best balance between capability and getting too far ahead of common usage in print workflows.
  • If you’re a print service provider, converter, industrial printing manufacturer or digital press vendor, don’t cut corners; use a workflow that applies the color management in or before the RIP4. It shouldn’t be hard; all the leading RIP vendors (and therefore leading press vendors, because they license technology from the RIP vendors) supply suitable systems.

About the author

Martin Bailey, consultant and former 0CTO, Global Graphics Software

Martin Bailey, consultant at Global Graphics Software, is a former CTO of the company and currently the primary UK expert to the ISO committees maintaining and developing PDF and PDF/VT. He is the author of Full Speed Ahead: how to make variable data PDF files that won’t slow your digital press, a guide offering advice to anyone with a stake in variable data printing including graphic designers, print buyers, composition developers and users.

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1 – If a spot color will be emulated using process inks on press, then using a CMYK alternate gives predictable color numbers in those inks, but is less good at producing a predictable color appearance. Using Lab for the alternate color space often leads to unpredictable color numbers on each separation, but a more predictable color appearance on the print. There is a benefit to both models, but when it comes to paying for printing the color appearance usually wins!

2 – if run-lengths on digital are long enough to justify warehousing a variety of inks, and changings inks on inkjet presses, it can be reasonable to stay with job-specific ink sets, especially if it’s difficult or expensive to make usable inks for all of CMY and K. As an example, the best Magenta ink for inkjet printing on ceramics is made with gold. Any move to using digital presses for short-run printing more or less requires a fixed ink set to allow for quick job changes without excessive waste, and that typically means CMYK+.

3 – and I say that as the chair of the committees that developed PDF/X for many years, first in CGATS and then in ISO.

4 – There are situations where applying color management in a color server before the RIP can be useful, especially when multiple presses will be used in parallel. This approach brings its own challenges around handling spot colors in the job that will be emulated on press, but can produce excellent results when used with care.

What is a Raster Image Processor (RIP)?

Ever wondered what a raster image processor or RIP does? And what does RIPping a file mean? Read on to learn more about the phases of a RIP, the engine at the heart of your Digital Front End (DFE).

The RIP converts text and image data from many file formats including PDF, TIFF™ or JPEG into a format that a printing device such as an inkjet printhead, toner marking engine or laser platesetter can understand. The process of RIPping a job requires several steps to be performed in order, regardless of the page description language (such as PDF) that it’s submitted in. Even image file formats such as TIFF, JPEG or PNG usually need to be RIPped, to convert them into the correct color space, at the right resolution and with the right halftone screening for the press.

Interpreting: The file to be RIPped is read and decoded into an internal database of graphical elements that must be placed on the output. Each may be an image, a character of text (including font, size, color etc), a fill or stroke etc. This database is referred to as a display list.

Compositing: The display list is pre-processed to apply any live transparency that may be in the job. This phase is only required for any graphics in formats that support live transparency, such as PDF; it’s not required for PostScript language jobs or for TIFF and JPEG images because those cannot include live transparency.

Rendering: The display list is processed to convert every graphical element into the appropriate pattern of pixels to form the output raster. The term ‘rendering’ is sometimes used specifically for this part of the overall processing, and sometimes to describe the whole of the RIPing process.

Output: The raster produced by the rendering process is sent to the marking engine in the output device, whether it’s exposing a plate, a drum for marking with toner, an inkjet head or any other technology.

Sometimes this step is completely decoupled from the RIP, perhaps because plate images are stored as TIFF files and then sent to a CTP platesetter later, or because a near-line or off-line RIP is used for a digital press. In other environments the output stage is tightly coupled with rendering, and the output raster is kept in memory instead of writing it to disk to increase speed.

RIPping often includes a number of additional processes; in the Harlequin RIP® for example:

  • In-RIP imposition is performed during interpretation
  • Color management (Harlequin ColorPro®) and calibration are applied during interpretation or compositing, depending on configuration and job content
  • Screening can be applied during rendering. Alternatively it can be done after the Harlequin RIP has delivered unscreened raster data; this is valuable if screening is being applied using Global Graphics’ ScreenPro™ and PrintFlat™ technologies, for example.

A DFE for a high-speed press will typically be using multiple RIPs running in parallel to ensure that they can deliver data fast enough. File formats that can hold multiple pages in a single file, such as PDF, are split so that some pages go to each RIP, load-balancing to ensure that all RIPs are kept busy. For very large presses huge single pages or images may also be split into multiple tiles and those tiles sent to different RIPs to maximize throughput.

The raster image processor pipeline. The Harlequin RIP includes native interpretation of PostScript, EPS, DCS, TIFF, JPEG, PNG and BMP as well as PDF, PDF/X and PDF/VT, so whatever workflows your target market uses, it gives accurate and predictable image output time after time.
The raster image processor pipeline. The Harlequin RIP includes native interpretation of PostScript, EPS, DCS, TIFF, JPEG, PNG and BMP as well as PDF, PDF/X and PDF/VT, so whatever workflows your target market uses, it gives accurate and predictable image output time after time.

Harlequin Host Renderer brochure


To find out more about the Harlequin RIP, download the latest brochure here.


This post was first published in June 2019.

Further reading:

1. Where is screening performed in the workflow

2. What is halftone screening?

3. Unlocking document potential

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RIP technology replacement achieves a faster development time, performance and quality benchmarks

 VIR Softech replaces RIP software for major print OEM and achieves a faster development time, performance and quality benchmarks

When a major print OEM switched from a market-leading RIP technology to the Harlequin RIP®, they achieved a faster development time and performance and quality benchmarks with a reduced bill of materials cost.

The Challenge
When a leading print OEM was looking to move to a PDF RIP technology that was easy to integrate and could help to achieve quality and performance benchmarks, it contacted Global Graphics Software Partner Network member, Vir Softech. As a RIP replacement service provider, the team at Vir Softech includes experienced engineers, with experts who have worked on all the major RIP technologies and understand the interfaces and functions they offer.

The Solution
Vir Softech recommended switching from the existing RIP technology to the Harlequin RIP from Global Graphics Software. Vir Softech had experience of using the Harlequin RIP in a similar project and knew it would meet the print OEM’s requirements. After a period of evaluation, including quality and performance benchmarking, the print OEM chose to use the Harlequin RIP.

Deepak Garg, managing director at Vir Softech explains the process: “The first step towards making the change was to assess and understand the various features and functions offered by the OEM’s print devices.”

After investigating, the team prepared a design document highlighting:

  • The OEM’s product features that interact with the RIP technology
  • How these product features are implemented
  • The various RIP interfaces which are used to implement these features and functions

Deepak continues: “Once the print OEM decided to go ahead, we prepared another document highlighting how to achieve these functions using the Harlequin interfaces. Some functions or features could not be implemented using Harlequin directly, such as special color handling, spot color replacement, extraction of cut data etc., so we contacted Global Graphics Software who was able to provide a design showing how these functions could be implemented using Harlequin. We then prepared a proof-of-concept, or working implementation, which demonstrated how the Harlequin RIP would work with the print OEM’s print devices. With Harlequin, such a prototype can usually be achieved within three to six months.”

The Result
Development time was much shorter than usual for such an ambitious undertaking, greatly reducing costs and enabling the print OEM to drive their revenue earlier than originally expected. The print OEM began using the Harlequin RIP, instantly meeting its quality and performance targets.

The print OEM says: “The Harlequin RIP helped us to move to native PDF printing and achieve the performance targets for our printers. Harlequin also helped us to reduce the lead time for getting our products to market while keeping development and maintenance costs low.”

About Vir Softech
Vir Softech is a technology start-up with expertise in imaging and computer vision technologies. With a strong focus in the Print & Publishing domain, its team of experienced engineers includes experts in all aspects of imaging and RIP technologies, such as job management, job settings, color management, screening, bands generation and management, VDP and imposition etc.

The team at Vir Softech are experts in configuring RIP technologies for better performance targeted for a specific market segment such as production, commercial, large format and enterprise printing. Some of the areas where Vir Softech can help include low resource environment, implementing OEM-specific unique functions using Harlequin RIP interfaces, making use of OEM ASIC for better performance, making use of OEM hardware accelerators for some of the computer-intensive RIP operations such as color conversion, image transformations, image decoding, rendering etc and achieving PPM target of MFP for ISO test suites.

To find out more about Vir Softech.