“Analogue Goes Digital!“ – one remembers how much excitement this slogan caused around 2003 when it was revealed to the image processing market. The giant analogue camera slice of the pie was shrinking as a result of an increasing digital solutions share. Even the components used for analogue solutions, e.g. frame grabbers, were affected by this development. An unparalleled feast seemed to have been laid out before the suppliers of digital cameras! All manufacturers with plans and products for the digital market waited eagerly.

But good things don’t happen overnight. The trend did not happen as quickly and vehemently as generally predicted – was it a result of the countercampaigns and steps by the manufacturers of analogue cameras and frame grabbers? Or was the reason that digital solutions didn’t really offer a realistic alternative to analogue systems? No matter where one looked, no real trend seemed to be appearing. Today, more than two years later, one can speak of a real market development and not only a trend. “Analogue Goes Digital” hasn’t been an advertising slogan for a long time, instead it has become more of a synonym for a steadily growing technological preference. What has been a standard for technical consumer goods is finally taking root in industrial applications. Slowly but surely, the giant analogue share is giving up ground to modern digital solutions.

And there is much of it: data transfer via digital ports such as USB2.0, Camera Link, IEEE1394a/b and Gigabit Ethernet (“GiGE-Vision”) are ready and just waiting for a moment of opportunity. But which one of these will make it? Which one will take over the final leading position? And: can there really be only one? In this article, we want to examine and answer these questions analytically. In the first step, let’s examine the currently estimated market situation that we have gained from various studies as well as regularly updated interviews with different camera, software and grabber manufacturers:

We can see that currently Camera Link and IEEE1394 are running neck and neck when it comes to the biggest market shares. Since both interfaces differ enormously with regards to their technical data, they have little in common on the market.

CameraLink is “the” digital interface based on a frame grabber. The rate of data transfer lets all current image processing possibilities pale in comparison. Up to 500 MByte/s can be sent to a computer. If needed, the frame grabber can help out the PC with pre-processing and storage components. The standard specially designed for image processing isn’t quite on a Plug and Play level, but working interfaces for most important cameras have been established by now. CameraLink is designed for industrial use and is thus especially suited for use in the Machine Vision field.

IEEE1394a, also called FireWire, is currently „the“ digital interface that works without a frame grabber. It is a standard feature on many PCs and enables the use of affordable computer accessories. It offers unparalleled ease of use as the IIDC standard (formerly DCAM) and achieves Plug and Play standards with up to 15 cameras on the bus. The only limit is the maximum data rate of around 32 MB/s, which is not enough for several applications. The standard is hardly static, however, but is continuously being developed thanks to its open architecture. IEEE1394b, IEEE1394a’s big brother, with double the data transfer rates (around 65 MB/s), seems to have broken the minimum entry level barriers. The new standard „B“ is backwards-compatible with the „old“ standard “A” and enters the race with its comfortable Plug and Play functionality and affordable accessories generated by the consumer market. The standard also makes the use of fiber optic cables feasible, which can reach lengths of up to 500 m, even with high noise levels.

USB2.0 is the most widely spread interface for computer accessories such as printers, scanners and digital cameras. One can barely find on computer that doesn’t have an USB port. Even when it comes to accessories, nothing is impossible. And a software standard has been established which defines the functions of digital cameras on the bus. It’s all been around for a long time but now there seems to be acceptance and interest in this interface. But still, most of the camera solutions do not reach all requirements of an industry level application. Presumably, the low cost applications and technologically simple camera solutions will be realised with USB2.0 in the future.

GiGE-Vision deserves special attention! Based on the Gigabit Ethernet network technology, a committee is currently working on defining a standard “GiGEVision” for image processing components. The first draft definition has been released during May 2005, which currently is checked on IP issues (Intellectual Property). The goal is to release the standard right in time for the Vision Show in Stuttgart / Germany (November). Hopefully, GiGE-Vision starts without the technical teething problems all the other standards have thus experienced. GiGEVision has a strong potential. With around 80 MB/s and a maximum of 100 m transfer range with a normal Ethernet cable it can – similarly to IEEE1394b – cover the technical needs of the majority of all applications. Accessories are plentiful and suitable for industrial environments in many cases. Without GenICam (see below) however, GiGE-Vision will not achieve a Plug and Play standard. Unfortunately, GiGE-Vision does not guarantee determinism in data transfer.

GenICam (formerly GenCam) is probably the most ambitious standardising image processing project. The GenICam standard is intended to be finished around autumn 2005. The goal is ambitious: an XML file, which the manufacturer supplied for the product, explains in detail how the camera works, which features are available and how they must be used. If everything works, this information is enough to use the camera with a PC with minimum effort and even integrate it into existing programs. Everything needed for this will be automatically generated (of course, software on the PC must be prepared and optimised in advance). GenICam is intended to work independently from the camera interface and be compatible with currently available cameras. This means that even IEEE1394 or CameraLink can benefit from it. It’s difficult to imagine – but what if these goals can really be achieved?

Once the PC is prepared for GenICam, all camera interfaces would equal a Plug and Play level. A change from one interface to another could become a simple step without having to adapt the application software. Dependence on the technology disappears and makes it easier for the camera user to switch to more suitable interfaces.

The technological strengths and weaknesses of an interface could have even more relevance in the coming years: The analogue market is passing its applications on to the relevant interfaces. In the low-cost field, the simple solutions can take a large share with IEEE1394a and USB2.0. The trend in this direction is already appearing. In the upper speed segment, CameraLink can continue to be successful and build on its position.

Concerning speeds under 80 MB/s, many clients will probably prefer interfaces that function without grabbers. IEEE1394b and GiGE-Vision can be successful alternatives here. The success of GiGE-Vision and GenICam depends on how error-free these standards really function and how long the way will be. The future is wide open.

Contact: Dipl.-Ing. Ingo Lewerendt Product Manager Allied Vision Technologies GmbH Tel.: +49-(0)36428-6770 info@alliedvisiontec.com www.alliedvisiontec.com