Issue #0639/1 - Windows Vista includes XPS, an electronic paper description module, which offers huge performance and cost benefits to the viewing, distributing and printing of electronic documents.
This week, just following the announcement that Vista is available to volume license holders and will be available to all users as of the end of January 2007, we take a look into XPS to find out a little more about what it is, what benefits is provides and why it presents us with these benefits.
As an integral part of this investigation, we take the opportunity to explain a little more of the principle of colour, how electronic colour works and how this is presented to us by computer screens and printers.
Much hype is often spread about before the launch of new Windows operating systems. Windows Vista is no exception.
But, we don’t often hear any mention of printing with regard to the new version.
This time, however, we are hearing plenty about the XPS printing capability of Windows Vista. So, how will the new system affect us in our everyday printing activities and will it bring any cost benefits?
Already available to volume license organisations, as of the beginning of December, individual and low-volume license holders will have to wait till the end of January to get their hands on Vista. Anyone who has recently purchased Windows XP, or purchases XP between now and full availability of Vista, will receive an upgrade voucher with their purchase. This means that buyers will not lose out just because they have to buy the outgoing operating system now.
Not normally noted for my enthusiasm for embracing a new operating system until it has bedded in and a service pack has been issued, Vista is catching my attention now and might well be in line for an early purchase.
Leaving aside all the changes other than those affecting print quality, speed and management, Windows Vista has a new ‘module’, if you like, called XPS – standing for XML Paper Specification. The very name implies that it is more than a suite of printer drivers, or print datastream handling or processing module, but that it affects almost every area of imaging and printing from a PC.
After all – the PC is all about documents and it is still proven that the number of documents committed to paper continues to be on the increase despite the stellar increase in email and web-based document distribution.
So, XPS is far more than a printer driver or imaging pipeline (image processing) for Vista, it is a whole suite of processes, applications and tools that work together to bring a wide range of document printing and management benefits to users.
Colour gamut
Much is made of the colour handling capabilities of XPS, so let’s start with a look at the range of colours we see, can view and can print.
RGB and CMY colour models- note the muddy colours
caused by the conversion
to CMY from RGB
Colours that we see are made up of a mix of light of three basic colours – Red Green and Blue (mixed together in equal quantities makes grey/white). On paper, the coloured inks required to produce colour are the exact opposites – Cyan, Magenta and Yellow (mixed together in equal quantities makes grey/black).
Colour gamut is the range of colours that a device, electronic display or printer is capable of reproducing with the information that is fed to it.
At its simplest level, think of this source data in terms of a black and white image (1bit image – black on or off). Any point within the image is defined by being either black or white and nothing else. Resulting images are coarse and harsh, with a clear grain to the image as the half-toning process attempts to create greys out of black.
From there, we progress to greyscale, which gives us a much better representation of the image because we are able to display varying shades of grey (usually defined by 8bit data – or up to 256 shades) within the image.
Then, we can add colour. The earliest colour computer screens (CGA) were capable of displaying 4 colours (2bit) – nice to have colour but totally unusable for anything other than text and line differentiation.
Moving on, computer displays graduated to 4-bit colour, giving us 16 colours, which gave a much more pleasant environment to work in but still presented a very coarse image that was unusable for photographic images. It did however, allow us an acceptable level of colour for basic business graphics and highlights.
After 16 colours came 256 colours (8bit), from which we obtained images that were just about acceptable for photographs (given the progression of available technology) but where distinct colour stepping meant that the image did not represent reality.
One step up from 256 colours came 16bit processing – 65,536 colours – much more acceptable for photographs and good enough for the average computer screen where the user wants to conserve processing power.
Finally, over the last few years, we have become accustomed to 32bit colour (often referred to as Truecolour). This is, in reality, 24bit colour (16.7 million colours) but with an extra 8 bits in the data because computer processing is handled in chunks of 32bits. This is the level at which the human eye can resolve distinct colours.
We arrive at 32bit colour from 8 data bits per channel – R G B – plus the additional unused 8 bits to bring the total up to 32 bits. Remember this fact because we will refer back to it when considering a third-party toolkit later on.
However, using the colour is a different matter and here we need to return to the principle that every device is capable of displaying a specific, and restricted, gamut – or range of colours.
Using this source data, a printer will make a translation into a form that it can use to drive the printer and the writing engine.
What we find is that a printer from one manufacturer will display a different colour range, or gamut, to a printer from another manufacturer, even when sent the same data, simply because the inks are different, have different chemical and colour characteristics and will display differently when mixed on the paper.
Indeed, use a different paper in your printer and the gamut will change because of the different interaction between inks, paper and reflectivity of the paper.
What this means is that we can throw 16.7 million colours at a printer with a very low colour gamut (say – 3-colour dot matrix) and we instantly lose a huge proportion of the original colour, achieving a very poor physical print.
Throwing that same data at an inkjet printer with 6 coloured inks (Cyan, Magenta, Yellow, PhotoCyan, PhotoMagenta and Black) will obviously result in a much better print because the printer has a much wider colour gamut. Some printers even work on a 9-ink system.
As printing technology continues to improve, we are able to achieve better reproduction of our images and Windows Vista, with XPS, will take us on a significant step in the pursuit of higher-quality photo printing.
To use an analogy, engines built for the cars we drive are designed to run on a specific grade – known as ‘octane’ – of fuel, with a number to indicate its potential energy. The basic, regular unleaded fuel is 87 octane, while premium unleaded fuels are 98 octane.
It is the car’s performance that is affected by the octane of the fuel, hence the recommendation from the manufacturer as to which fuel the engine was designed for to provide optimum performance.
In the UK, the most common fuels available are 95 and 98 octane. In Australia, it includes 91 octane and, in the US, the lowest grade is 87 octane, rising to 91.
Using the wide-ranging Australian model, research shows that, while no harm will come to a car designed to run on low-octane fuel (91) by filling up with high-octane fuel (98), there will not be a guaranteed performance benefit either.
However, an engine designed to run on 98 octane fuel will benefit from a range of advantages, namely: improved engine responsiveness; better fuel economy; greater fuel efficiency; cleaner engine; better driveability; lower emissions and therefore a cleaner environment.
But, we also need to look at the situation from the other side. A loss of performance will be experienced if an engine designed to run on 98 octane fuel is fed with 91 octane fuel.
Imagine how a 1957 Formula One race car, designed for 130 octane fuel, or a 110 octane NASCAR vehicle, would run on 87 octane unleaded fuel from the US?
We experience exactly the same relationships when talking about colour gamut, electronic data and displays or printers. Feeding high-octane data to a low-octane device can’t do any harm but we suffer a serious loss of performance if we feed a high-octane device with low-octane data.
In the image below, you will see three distinct shapes represented by different densities of transparency. This is a graphical 3D representation of colour gamut where a greater distance from the origin indicates a wider spread of colours.
In the centre, the lightest shape, is the representation of the colour gamut produced by sRGB (the most common colour system used by the Windows operating system).
Outside the sRGB colour space, is a larger shape that represents the Adobe RGB colour system – wider gamut, capable of displaying more colours than sRGB.
Then further outside the Adobe RGB colour space is one additional shape that represents the colour capabilities of the raw data from a digital camera, indicating that Camera Raw images hold far more information than sRGB or even Adobe RGB colour systems.
At this point we need to note that a JPEG image from a digital camera does not carry as wide a gamut as the raw camera data. This means that colour is being thrown away every time we, or our camera, converts a raw image into a JPEG image.
However, it also means that we are throwing away colour data whenever we view an image on a PC display, TV or digital projector.
One further stage - it also means is that we lose colour information when we print an image (camera raw) and commit it to paper. However, as the latest photo printers are capable of printing a larger colour gamut than the sRGB colour system, and improving with every new generation, we should be able to enjoy photographs more by viewing them in printed form than on-screen.
XPS and Vista handle more of the original colour information in the image, meaning that more accurate colour is sent to the printer and our prints are then limited only by the capabilities of ink, toner and paper and not by the data source providing the image to the printer.
Although we have focussed here on the handling of images, because this helps us in an explanation of colour gamut, XPS is relevant to any document.
Data processing
Within Vista, XPS is responsible for the image handling of all documents, with all the colour control and image processing that is involved. As Microsoft explains, “XPS describes electronic paper in a way that can be read by hardware, read by software, and read by humans”. It is an equivalent to – and much more besides – the Page Description Languages (PDLs) that we are so familiar with - Hewlett-Packard’s PCL, Adobe’s PostScript, etc.As a PDL, one of the main functions of XPS is to present the document file in a format that is viewable exactly as the document will print. Thus, an XPS document becomes a replacement for a PDF document. It is intended that this document can be viewed by any computer user. There will just be the proviso that users must be running either Windows Vista or another operating system with an XPS viewer plug-in (much the same as the PDF viewer we know today).
Because the XPS document is effectively pre-formatted, less processing power has to go into the printing procedure – meaning that the speed of printing is improved (especially complex graphical documents and images) by getting the data to the printer much faster and with fewer data translations involved.
As well as speeding up the printing process, the more efficient data handling will shorten the length of time taken for the PC to return control to the application you are using (especially if the printer is a GDI printer). Thus, users will feel the benefit immediately because they will be able to continue with the next task much faster.
This is one of the areas in which Vista and XPS can be considered to provide cost benefits to users. Particularly in graphical intensive environments, e.g. graphic arts and production of marketing materials, the processing time required for documents to be printed is significant. Slashing this processing time will bring high value to these environments.
Printer drivers
Although printing of documents from Windows Vista will be faster, even on an existing printer, maximum benefit will be achieved by using an XPS printer because the printer is capable of handling the high quality XPS source data directly, without having to rely on intermediate data translations to provide the printer with something that it can understand.Full advantages of XPS processing combined with XPS printing will include:
- wider colour gamut …
- leading to smoother and more accurate printing of on-screen colour gradients, cut-outs and transparencies (increasingly used in the graphic arts environment and in the production of marketing materials) because the printer receives the full source data, not a subset, without any intermediate translations
- processing of colour gradients will be much faster
- and spool files will be much smaller (down to a few hundred kilobyte from multi-megabyte) because processing is more efficient …
- leading to much faster printing (making the most of engine speed) with lower network overheads …
- and faster return to application for the user
Faster and more accurate printing is a real driver for more cost-effective printing: faster return to application and faster printing means less wasted time; and more accurate colour means fewer wasted proof prints.
Further efficiency is targeted through Microsoft’s goal to achieve a single set of printer drivers, embedded within the operating system, so that users have the definitive driver immediately to hand, thus avoiding the current situation where users could be running any one of: the manufacturer’s driver; a Windows driver; or even, in some instances, a third party driver (especially relevant to the CADCAM environment).
There are currently more than 6,000 printer drivers available in 64bit versions of Windows, ranging from consumer inkjet to high level laser MFPs, plus a few specialist drivers (CADCAM/wide format).
Corporate printer driver installation
Part of Windows Vista’s new feature set is the ability to handle the installation of printer drivers in a more efficient and secure manner.Real cost-saving value to large organisations is achieved by allowing any user to install a device driver (printer or otherwise) once it has been loaded onto the system – signed and verified, with installation rights, by an administrator.
No longer does the IT technician or administrator physically need to do the driver installation individually for each user, representing a considerable savings potential.
Controlling which users are allowed which device drivers is greatly improved by setting installation rights centrally – and just once.
Data security is also greatly improved by the control of driver installation. In particular, Vista will distinguish between printer drivers and USB device drivers (for instance), thus providing an additional means of preventing unauthorised extraction of data from corporate IT systems.
More than a colour system and printer driver
As mentioned however, XPS is much, much more than an image processing or printer driver suite.In addition to the basic advantages of containing high fidelity image data and printed page formatting, XPS also contains document management and rights management capabilities – with digital signature and rights management information held within the XPS document itself.
In reality this has three major implications:
- any document can carry the personal digital signature of its creator, together with usage rights (e.g. copying, saving, printing, modifying)
- an MFP scanning a document can embed the personal digital signature of the user within the document before that document is distributed
- a filter pipeline that integrates with the digital workflow allows improved functionality within the system. For instance, a document could be archived automatically as it is printed.
XPS is Open Architecture
XPS is also platform independent and not subject to royalties, using the XML open architecture format, meaning that anyone can have access to it specification free of charge.This should help to ensure ongoing future-proofing of documents – guarding against documents becoming unreadable as software applications disappear. Never afraid to take a snipe at arch-enemy, WordPerfect, Microsoft likes to use WordPerfect as an example of a defunct application even though it still accounts for some 15% of the office suite market!
So, with XML formatting, any developer can build applications with XPS functions for reading, modifying, writing, printing, archiving and distributing workflow documents.
To ensure universality of the format, an XPS viewer is embedded within Vista and is available as a free plug-in for Windows XP. So, no-one should have any difficulty reading a file that is distributed as XPS.
There is also a driver component incorporated in Vista so that XPS documents can be created from an XPS compliant application.
Third party XPS activities
Third party software and hardware manufacturers are gearing up for supporting XPS and maximising its potential.Software Imaging, Xerox and Oki are three that have caught our attention but every company involved in the PC hardware, software and printer industry will also be working on their respective solutions. If they didn’t, XPS would be almost useless to us.
Just announced (6th December) by Software Imaging is the ColorCore 3 software development kit (SDK) for printer manufacturers. Software Imaging (formerly Software 2000) is the foremost developer of the building blocks for manufacturers to create their printer drivers.
ColorCore 3 is a set of advanced photo imaging and rendering technologies that enables the OEM to build a custom driver for each specific printer, drawing on the capabilities of XPS and Vista.
One has to wonder about the timing of this launch when Vista is already shipping to large organisations and the development kit is targeted at printer manufacturers – who should now be announcing their own XPS solutions in support of Vista rather than just starting to develop them.
For instance, Fuji Xerox was the first printer manufacturer to be involved with XPS. A Microsoft spokesman says that Fuji Xerox “… basically ripped it out of our [Microsoft’s] hands right from its earliest specification stage”. Fuji Xerox has been developing from the beginning and has had prototype XPS printers running for some while.
ColorCore 3 renders image/page data to 16 bits per channel (RGB) from Windows Vista XPS applications into individual colours (CMYK) for printing, using 256 levels of intensity per colour. The technologies behind the product have been developed by Software Imaging over years of research and stand sharply in contrast to some printer technologies that are limited to 2bit per channel processing (4 levels of intensity per print colour).
This depth of processing maximises the depth of colour information that is available from XPS, with all the implications of greater colour accuracy and wider colour gamut.
In order to achieve maximum benefit from XPS, Software Imaging says that printer manufacturers must support 16bit per channel processing and not reprocess the data to 8 bits per channel (remember the definition of colour in the section entitled Colour Gamut?). To do so, Software Imaging believes they will need the ColorCore 3 development kit.
In addition, applications and drivers will need to catch up before the x64 environment (64bit processing, likely to be popularised by the 64bit version of Vista) is fully up and running.
Summary of cost benefits
Improved print speed and colour fidelity is not where the benefits of XPS end.We have seen that cost implications result from:
- distributed installation of printer and other device drivers
- improved print speed
- reduced network overhead
- higher colour accuracy…
- meaning fewer wasted proof prints
Summary
Microsoft probably hopes that XPS will replace Adobe PDF as the de facto standard for distribution of electronic documents. Certainly as an XML-based format, with all the associated future-proofing advantages, and as an integral part of the new Windows Vista operating system, XPS will bring wide-ranging benefits to the majority of users automatically, without even the need to download additional drivers or viewers.These benefits may take a year or more to become fully apparent as third party developers get to grips with XPS and present their hardware and software solutions to the market and as users make the transition to Vista, either with new PC purchases or with upgrades to their existing operating systems.
Windows Vista will be available in both 32bit and 64bit formats, so users with recent PCs won’t be obliged to upgrade the PC just to benefit from Vista and XPS.
In addition, the XPS viewer will be available as a plug-in for Windows XP, so as soon as organisations begin producing documentation in XPS format (instead of PDF!) users will be able to read the files.
Clearly, the main benefit of XPS lies in the processing of colour data through the 16bit per channel imaging pipeline, such as raw camera images, and the resulting improvement in the ability of output devices to reproduce high accuracy colour, with a wide colour gamut, fast.
Rather surprisingly, Microsoft has no plans to issue a branding or identity for XPS that can be displayed on XPS printers.
While, in the long term, this is no issue because there will be a natural progression to XPS as new generations of printers are released, in the short to medium term this is an issue because users will have to dig for XPS compliance information in the same way that they have to dig for Cost of Printing information.
~End~
