During the event, HP launched the Indigo 5500 and 3500, which are upgraded versions of the 5000 and 3050 models launched in 2005. Of course, there have been more improvements in productivity, paper handling and front-end capabilities as one might expect with a new product generation. Even printing on uncoated and untreated offset stock is possible now, so using the same paper on an HP Indigo press and an offset is possible. Undeniably, these are important features which will make many users happy, but what particularly stands out are the improvements in digital colour print quality.

With the introduction of the these latest HP Indigo models, it is obvious that quality is not an issue any more when judging the merits of digital print. The quality of skin tones, reproduction of pastel colours, and smoothness of blends can match the best of offset. HP also introduced light cyan and light magenta as additional colours – these are familiar additions to the ink sets of many desktop photo printers. As a result, the prints look much more like photographs without visible rosette patterns in the halftones.

Another new feature is called ‘solid line work thinning’ to enable printing of hair lines and 0.8pt micro text for sans serif fonts. The effect is achieved by reducing the power of the imaging laser when imaging fine lines, supported by an increased resolution of 1,200dpi. Add to that the new HP developed UV coater, which can be installed on-line or near-line, and you have a premium quality print factory.

Adaptable imaging
I would even argue that digital has an edge in quality on offset when it comes to controlling density fluctuations from sheet to sheet and across the image. In-line sensors can detect changes in density and adapt the image accordingly from sheet to sheet or even within the image. The progress in control that has been made here is remarkable to ensure consistency and repeatability and is worlds apart from the troubles of the first models. In comparison, conditions on an offset press do shift and there is no way to adapt the image on a plate to make adjustments. Adjusting ink-setting, water and pressure settings remains a relatively crude tool with a considerable time lag between action and result.

Anybody dismissing digital print quality as inferior today should have a second look at the latest generation machines. There are good reasons and applications for each printing process and economic models to fit many technologies, but quality shouldn’t be a topic anymore when discussing the use of digital colour print.

Speed limitations
The latest generation of HP Indigo machines show impressive progress, however, despite all the improvements, in my opinion there is one big challenge remaining: the speed. With an unchanged speed of 68 four-colour A4 pages a minute, the HP Indigo presses remain at the same colour speed level that was shown at Drupa 2000.

A few weeks ago, Kodak announced a 100 page per minute (ppm) NexPress to be launched this autumn. Xerox is already at 110ppm with the iGen3 110. The speed record for graphic arts quality colour presses is undoubtedly set by the Xeikon 6000 with 160 pages per minute. That is nearly two and a half times as fast as both HP Indigo models. One might argue how much speed is actually needed and opinions on the desired level will differ but, in the end, speed is not a virtue in itself. Rather, speed is a cornerstone of productivity which, in turn, can improve economics dramatically. With that being tackled, there is no reason why digital can’t take a larger share of the printing pie.

Digital printing is still a rapidly developing technology and we certainly have more progress and innovation to look forward to at Drupa next year.

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Ralf Schlözer is associate director at digital print and document technology analyst Infotrends. Email ralf_schlozer@capv.com