Choosing the class of your raster image processor (RIP) – Part II

Part II: Factors influencing your choice of integration

If you’re in the process of building a digital front end for your press, you’ll need to consider how much RIPing power you need for the capabilities of the press and the kinds of jobs that will be run on it. 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 print head, toner marking engine or laser plate-setter can understand. But how do you know what RIP is best for you and what solution can best deliver maximum throughput on your output device? In this second post, Global Graphics Software’s CTO, Martin Bailey, discusses the factors to consider when choosing a RIP.

In my last post I gave a pointer to a spreadsheet that can be used to calculate the data rate required for a digital press. This single number can be used to make a first approximation of which class of RIP integration you should be considering.

For integrations based on the Harlequin RIP® reasonable guidelines are:

  • Up to 250MB/s: can be done with a single RIP using multi-threading in that RIP
  • Up to 1GB/s: use multiple RIPs on a single server using the Harlequin Scalable RIP
  • Over 1GB/s: use multiple RIPs spread over multiple servers using the Harlequin Scalable RIP

These numbers indicate the data rate that the RIP needs to provide when every copy of the output is different. The value may need to be adjusted for other scenarios:

  • If you’re printing the same raster many times, the RIP data rate may be reduced in proportion; the RIP has 100 times as long to process a PDF page if you’re going to be printing 100 copies of it, for instance.
  • If you’re printing variable data print jobs with significant re-use of graphical elements between copies, then Harlequin VariData™ can be used to accelerate processing. This effect is already factored into the recommendations above.

The complexity of the jobs you’re rendering will also have an impact.

Transactional or industrial labelling jobs, for example, tend to be very simple, with virtually no live PDF transparency and relatively low image coverage. They are therefore typically fast to render. If your data rate calculation puts you just above a threshold in the list above, you may be able to take one step down to a simpler system.

On the other hand, jobs such as complex marketing designs or photobooks are very image-heavy and tend to use a lot of live transparency. If your data rate is just below a threshold on the list above, you will probably need to step up to a higher level of system.

But be careful when making those adjustments, however. If you do so you may have to choose either to build and support multiple variations of your DFE, to support different classes of print site, or to design a single model of DFE that can cope with the needs of the great majority of your customers. Building a single model certainly reduces development, test and support costs, and may reduce your average bill of materials. But doing that also tends to mean that you will need to base your design on the raw, “every copy different”, data rate requirements, because somebody, somewhere will expect to be able to use your press to do just that.

Our experience has also been that the complexity of jobs in any particular sector is increasing over time, and the run lengths that people will want to print are shortening. Designing for current expectations may give you an under-powered solution in a few years’ time, maybe even by the time you ship your first digital press. Moore’s law, that computers will continue to deliver higher and higher performance at about the same price point, will cancel out some of that effect, but usually not all of it.

And if your next press will print with more inks, at a higher resolution, and at higher speed you may be surprised at how much impact that combination will have on the data rate requirements, and therefore possibly on the whole architecture of the Digital Front End to drive it.

And finally, the recommendations above implicitly assume that a suitable computer configuration is used. You won’t achieve 1GB/s output from multiple RIPs on a computer with a single, four-core CPU, for example. Key aspects of hardware affecting speed are: number of cores, CPU clock speed, disk space available, RAM available, disk read and write speed, band-width to memory, L2 and L3 cache sizes on the CPU and (especially for multi-server configurations) network speed and bandwidth.

Fortunately, the latest version of the Harlequin RIP offers a framework that can help you to meet all these requirements. It offers a complete scale of solutions from a single RIP through multiple RIPs on a single server, up to multiple RIPs across multiple servers.

 

The above is an excerpt from our latest white paper: Scalable performance with the Harlequin RIP. Download the white paper here.

Read Part I – Calculating data rates here.

Choosing the class of your raster image processor (RIP) – Part I

Part I: How to calculate data rates

If you’re in the process of choosing or building a digital front end for your press, you’ll need to consider how much RIPing power you need for the capabilities of the press and the kinds of jobs that will be run on it. 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. But how do you know what RIP is best for you and what solution can best deliver maximum throughout on your output device? This is the first of two posts by Global Graphics Software’s CTO, Martin Bailey, where he advises how to size a solution for a digital press using the data rate required on the output side.

Over the years at Global Graphics Software, we’ve found that the best guidance we can give to our OEM partners in sizing digital press systems based on our own solution, the Harlequin RIP®, comes from a relatively simple calculation of the data rate required on the output side. And now we’re making a tool to calculate those data rates available to you. All you need to do is to download it from the web and to open it in Excel.

Download it here:  Global_Graphics_Software_Press_data_rates

You will, of course, also need the specifications of the press(es) that you want to calculate data rates for.

You can use the spreadsheet to calculate data rates based on pages per minute, web speed, sheets or square meters per minute or per hour, or on head frequency. Which is most appropriate for you depends on which market sector you’re selling your press into and where your focus is on the technical aspects of the press.

It calculates the data rate for delivering unscreened 8 bits per pixel (contone) rasters. This has proven to be a better metric for estimating RIP requirements than taking the bit depth of halftoned raster delivery into account. In practice Harlequin will run at about the same speed for 8-bit contone and for 1-bit halftone output because the extra work of halftoning is offset by the reduced volume of raster data to move around. Multi-level halftones delivered in 2-bit or 4-bit rasters take a little bit longer, but not enough to need to be considered here.

You can also use the sheet-fed calculation for conventional print platesetters if you so desire. You might find it eye-opening to compare data rate requirements for an offset or flexo platesetter with those for a typical digital press!

Fortunately, the latest version of the Harlequin RIP offers a framework that can help you to meet all these requirements. It offers a complete scale of solutions from a single RIP through multiple RIPs on a single server, up to multiple RIPs across multiple servers.

In my next post I’ll share how the data rate number can be used to make a first approximation of which class of RIP integration you should be considering.

 

The above is an excerpt from our latest white paper: Scalable performance with the Harlequin RIP®. Download the white paper here

What does a RIP do?

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

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 print head, toner marking engine or laser platesetter can understand. The process of RIPing a page requires several steps to be performed in order, regardless of whether that page is submitted as PostScript, PDF or any other page description language.

Interpreting: the page description language to be RIPed is read and decoded into an internal database of graphical elements that must be placed on the page. 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 pages in PDF and XPS jobs that use live transparency; it’s not required for PostScript language pages 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. It’s only used it in the first sense in this document.

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.

RIPing 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 is applied during rendering or after the Harlequin RIP has delivered unscreened raster data if screening is being applied post- RIP, when Global Graphics’ ScreenPro™ and PrintFlat™ technologies are being used, for example.

These are all important processes in many print workflows.

 

The Harlequin Host Renderer
The Harlequin RIP includes native interpretation of PostScript, EPS, DCS, XPS, JPEG, BMP and TIFF 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 above is an excerpt from our latest white paper: Scalability with the Harlequin RIP®. Download the white paper here

Adjusting rendering of outlined text in Harlequin

By Martin Bailey, CTO, Global Graphics Software

In several sectors of the print market it is common practice to convert text to outlines upstream of a RIP, on the grounds that it’s then impossible for the wrong glyph to be printed. This is normal, for instance, in much of the label and packaging industry, especially when there is very robust regulation in place, such as in pharmaceuticals.

Every page description language defines “scan conversion” rules that specify which pixels should be marked when a graphic is painted onto a page; these build on the concept of “pixel touching”, specifying exactly when a vector shape counts as touching a pixel and therefore marking it.

When you’re using PDF (or PostScript, before that) the scan conversion rules are different for text specified using live fonts and for vector shapes. If you started with live text and then converted it to outlines then you have switched from using the text scan conversion rules to using the vector graphic rules. That has always meant that text converted to outlines tends to render slightly heavier than text using live fonts. And the smaller the text is, the more the weight difference becomes apparent.

FIG 1
FIG 1 – 2pt text in Times Roman showing various scan conversion rules.

In Fig 1 you can see this difference very clearly for very small Western text rendered at 2pt and 600dpi, still a common resolution for digital printers and presses. The top line shows text using live fonts, and the second line shows the PDF scan conversion rule for a vector fill. Note that at 2pt the RIP only has about 12 pixels for the height of an upper-case glyph.

In early 2018 we added a new scan conversion rule for vector fills alongside our pre-existing rules in the Harlequin RIP. The intention was to make it possible to emulate the much lighter output that Esko’s FlexRIPs produce. Unfortunately, it also tended to emulate the ability for very fine structures, especially fine horizontal strokes in small text, to disappear. You can see this in the third row of text in Fig 1.

This is obviously not an optimal solution, so we continued our development, and have now extended the original solution with what is called “dropout control”. This prevents very fine sections of a vector fill “dropping out” when they manage to fall on the page in such a way that they don’t cross the locations in the pixels that would trigger anything being marked. You can see the effect of this in the bottom line in Fig 1.

Light rendering with dropout control was delivered to our OEM partners in late 2018 under the name RenderAccurate.

Even this optimized output won’t exactly match the output of live fonts, because the fonts themselves often include hints to the rendering engine, designed to ensure maximum legibility and conformance to the font designer’s vision. These hints can, for instance, ensure that vertical stems are the same width in all glyphs, or that the curved base of a glyph will extend slightly below the baseline to make it visually balance with glyphs with flat bases that sit on the baseline. Those hints were discarded when the text was converted to an outline, and so can’t be used any more. But the new scan conversion algorithm certainly strikes a good balance between matching the weight of live fonts and maintaining legibility.

The effect is visible in very small text in Latin fonts, as shown in Fig 1, but the impact is often masked by the physical effects of printing. And Latin glyphs tend to be relatively simple, so that the human eye and brain are pretty good at filling in the missing segments without too much impact on legibility or comprehension.

On the other hand, Chinese, Japanese and Korean (CJK) fonts are often more complex, with the result that the effect is visible at larger point sizes. And the meaning can be obscured or altered much more easily if strokes are missing. Fig 2 illustrates the same effects on Japanese text at 3pt, rendered at 600dpi. At this size and resolution, the RIP has about 22 pixels for the height of each glyph.

FIG 2
FIG 2 – 3pt text in MS Mincho, showing, from top to bottom: live fonts; default rendering for outlined text; the new, lighter, outlined text; and lighter text with dropout control.

The glyphs shown in FIG 2 are complex compared to Western scripts, but any solution that will be used with CJK scripts must obviously also be proven with the most complex character shapes, such as the Kanji in FIG 3. Some of these have so many horizontal strokes that they simply cannot be rendered with fewer than 22 device pixels vertically and require more than that for reliable rendering. The sample in this figure is rendered at with around 27 pixels for the height of each glyph.

FIG 3
FIG 3 – More complex Kanji in KozGoPro-Regular, showing, from top to bottom: live fonts; default rendering for outlined text; and the new, lighter text with dropout control.

This article has deliberately used very small text sizes as examples, simply because the effects are easier to see. But the same issues arise at larger sizes as well, albeit more rarely.

On the other hand, it is precisely because the issue appears more rarely, and because the effects are less immediately noticeable, that makes the risk of dropping strokes so dangerous. It’s perfectly possible that an occasional missing stroke, perhaps in an unusually light font, may go unnoticed in process control. And that might result in a print that disappoints a brand owner, or even that fails a regulatory check, after the label has been applied or the carton converted and filled, or even after the product being shipped.

So, when a brand demands lighter rendering of pre-outlined fonts, make sure you’re safe by also using dropout control in your RIP!

New to inkjet? Come and see us at Hunkeler Innovationdays

Martin Bailey, CTO, Global Graphics Software
Martin Bailey, CTO, Global Graphics Software

If you are new to inkjet and are building your first press no doubt you’ll have many questions about the workflow and the Digital Front End.

In fact, you’re probably wondering how to scope out the functionality you need to create a DFE that is customised to exactly what your customers require. Among your concerns will be how you’re going to achieve the throughput you need to keep the press running at rated speed, especially when handling variable data. Or it might be handling special colours or achieving acceptable image quality that is keeping you awake at night.  And how to achieve this without increasing the bill of materials for your press?

At Hunkeler Innovationdays we’ll have a range of resources available to address just such questions with some real case study examples of how our OEM customers have solved the problems that were causing them a headache using our technology and the skills of our Technical Services team.

For instance, how, on a personalised run, when every label or page might be different, can you stop the press from falling idle whilst the RIP catches up?  Our ScreenPro™ technology helps Mark Andy cut processing time by 50% on the Mark Andy Digital Series HD, enabling fully variable (every label is different) continuous printing at high-speed and at high-quality.

How can you avoid streaking on the image if your substrate is racing under your printheads at speeds of up to 300m/min for aqueous and maybe 90m/min for UV.  Or mottling? The Mirror and Pearl Advanced Inkjet Screens™ available with ScreenPro have been developed specifically to address these problems.

During the lifetime of the press, how can you avoid variations in quality that look like banding because your printheads have worn or been replaced?  Take a look at what Ellerhold AG has achieved by deploying PrintFlat™.

The ScreenPro screening engine is one of the building blocks you’ll need for your inkjet press. Our Fundamentals components provide other functions that are essential to the workflow such as job management, soft proofing, and colour management.

Using a variety of white papers, print samples, video footage and case studies , we’ll be sharing our experience.  So, come along and meet the team:  that’s me, Jeremy Spencer, Justin Bailey and our colleague Jonathan Wilson from Meteor Inkjet if you want to chat about their printhead driver electronics that are endorsed by the world’s leading industrial inkjet printhead manufacturers.

 

Join us at Hunkeler Innovationdays 2019

 

What’s new in Harlequin Version 12?

Yesterday saw the launch of the latest version of the Harlequin RIP®. It’s the first major PDF RIP for production printing to offer compatibility with the PDF 2.0 standard and is packed with features for high-speed digital printing, including Advanced Inkjet Screens™ that improve output quality, further additions for labels and packaging applications, and new features for wide format and envelope printing.

Check out the video, where Global Graphics CTO Martin Bailey introduces Version 12 and highlights compatibility with PDF 2.0, dynamic overlays and In-RIP bar code generation:

You’ll also find more information on our website: https://www.globalgraphics.com/globalgraphics-software/products/harlequin-host-renderer-sdk

 

What do you really need in a RIP to drive a digital press in labels & packaging?

In this latest post, Global Graphics CTO Martin Bailey goes back to basics and explores what you need in a RIP to drive a digital press for labels & packaging.

Martin highlights rendering your jobs correctly, color management with CMYK inks and spot colors, PDF layering and technical separations, and provides a high-level view of the features of the Harlequin RIP® for digital labels and packaging.

Watch Martin’s presentation here:

Follow us on Twitter: @Global_Graphics

Harlequin RIP helps to drive the new HP Production Pro for Indigo Labels & Packaging

Our corporate communications director, Jill Taylor, talks to Roy Faigenbloom of HP Indigo at Labelexpo Europe last month about the new digital front end driving the HP Production Pro for Indigo labels & packaging.

HP Indigo chose the Harlequin RIP as the RIP engine in this new DFE, which has been designed to drive all HP Indigo digital labels and packaging presses and has been rated as 5x faster than the previous DFE.

 

Getting to know PDF 2.0

Are you ready for PDF 2.0? Register now for the PDF 2.0 interoperability workshops in the UK and USA.

Just when you’ve all cozied down with PDF 1.7 what happens?  Yes, that’s right.  A new standard rears its head.

Around the middle of 2017 the ISO committee will publish PDF 2.0 (ISO 32000-2). So by the end of 2017 you’ll probably need to be considering how to ensure that your workflow can handle PDF 2.0 files correctly.

As the primary UK expert to this committee I thought I’d give you a heads up now on what to expect.  And over the coming months via this blog and our newsletter I’ll endeavor to keep you posted on what to look out for as far as print is concerned.  Because, of course, there are many aspects to the standard that do not concern print at all.  For instance there are lots of changes in areas such as structure tagging for accessibility and digital signatures that might be important for business and consumer applications.

As you probably already know, in 2008 Adobe handed over ownership and development of the PDF standard to the International Standards Organization.  Since that time I’ve been working alongside other experts to ensure that standards have real-world applicability.

And here’s one example relating to color.

The printing condition for which a job was created can be encapsulated in professional print production jobs by specifying an “output intent” in the PDF file. The output intent structure was invented for the PDF/X standards, at first in support of pre-flight, and later to enable color management at the print site to match that used in proofing at the design stage.

But the PDF/X standards only allow a single output intent to be specified for all pages in a job.

PDF 2.0 allows separate output intents to be included for every page individually. The goal is to support jobs where different media are used for various pages, e.g. for the first sheet for each recipient of a transactional print job, or for the cover of a saddle-stitched book. The output intents in PDF 2.0 are an extension of those described in PDF/X, and the support for multiple output intents will probably be adopted back into PDF/X-6 and into the next PDF/VT standard.

But of course, like many improvements, this one does demand a little bit of care. A PDF 1.7 or existing PDF/X reader will ignore the new page level output intents and could therefore produce the wrong colors for a job that contains them.
In my next post I’ll be covering changes around live transparency in PDF 2.0.  Bet you can’t wait!
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The background
The last few years have been pretty stable for PDF; PDF 1.7 was published in 2006, and the first ISO PDF standard (ISO 32000-1), published in 2010, was very similar to PDF 1.7. In the same way, PDF/X 4 and PDF/X 5, the most recent PDF/X standards, were both published in 2010, six years ago.

In the middle of 2017 ISO 32000-2 will be published, defining PDF 2.0. Much of the new work in this version is related to tagging for content re-use and accessibility, but there are also several areas that affect print production. Among them are some changes to the rendering of PDF transparency, ways to include additional data about spot colors and about how color management should be applied.

What is a successful beta test?

You often read news items about a new press having been installed at a beta site but it’s not a topic that gets much of an airing apart from the odd news bulletin, is it?

And that got me thinking.

What is considered to be a successful beta test?  And why should we care?

Well, if you do care, you are not just going through the motions to get your press out of the door. You are more likely to be focussed on delivering a good product. You probably view beta testing as an opportunity to make changes for the better and to help improve product management. You care what comes back because you want to develop a good product. It’s important to you to get understandable and useful data.

So what do you want to know? Your beta test should provide you with proof points as to why your printer is going to be successful in the market. “Real” users will use and abuse your press and put it through its paces in a way that your own internal hardware and software engineers will not. Any weaknesses will be exposed. And you’ll get closer to your customer by working together with them in a way that just wouldn’t be open to you if you didn’t run a beta program.

The thing is how do you extract meaningful data from your test? And how do you rule out those problems that have nothing to do with your press, such as humidity, ambient temperature, the way the site is being operated?

Somehow you need to control the environment that the beta test is conducted in and approach the beta test in quite a formal way to rule out any subjectivity that might creep in.

We’ve got some ideas on how to achieve this which I’ll share in another post. But I’d be interested in hearing how you do it. What are your top tips?