In the industrial image processing world, there are standards – GenICam, GigE Vision, and USB3 Vision – that are similar to the USB and Ethernet standards used in consumer products. What do these image processing standards mean, and what are their benefits?
The GenICam standard, which is maintained by the European Machine Vision Association (EMVA), serves as a base for all the image processing standards. This standard abstracts the user access to the features of a camera and defines the Standard Feature Naming Convention (SFNC) that all manufacturers use so that common feature names are used to describe the same functions.
Additionally, manufacturers can add specific “Quality of Implementation” features outside of the SFNC definitions to differentiate their products from ones made by other manufacturers. For example, a camera can offer specific features like frame average, flat field correction, logic gates, etc. GenICam/GigE Vision-based driver and software solutions from other manufacturers can also use these features without any problem.
“On-the-wire” standards
USB3 Vision and GigE Vision are “on-the-wire” interfaces between the driver and the camera. These standards are maintained by the Automated Imaging Association (AIA). You are probably familiar with “on-the-wire” standards and their advantages if you have used plug-and-play devices like USB memory sticks, USB mice, or USB hard disks. They work together without any problem, even if they are made by different manufacturers. It’s the same thing with GenICam/GigE Vision/USB3 Vision-based driver/software solutions. The standards define a transport layer, which controls the detection of a device, configuration (register access), data streaming (device detection), and event handling, and connects the interface to GenICam (Figure 1).
USB3 Vision builds on the GigE Vision standard by including accessories like cables. The mechanics are part of the standard and defines lockable cable interfaces, as one example. This creates a more robust interface for manufacturing environments.
Are standards a must-have?
Technically, standards aren’t necessary. But they make it possible to use products from multiple manufacturers and make devices more useful in the long term. For a historical comparison, look at USB 2.0 cameras and GigE Vision. USB 2.0 industrial cameras were introduced in 2004 and only worked with proprietary drivers (Figure 2) between the client and Vision Library/SDK and between the driver and camera. Two years later, Gigabit Ethernet cameras were introduced with the GigE Vision image processing standard, which didn’t require proprietary drivers to operate.
In the case of a system crash, users of the USB 2.0 cameras wouldn’t know whether the proprietary driver or the software library was to blame, which made them difficult to support. During the decision phase of selecting sensors and support, the customer had to keep the product portfolio in mind to meet their specifications. Afterward, the application was implemented and only worked with the proprietary interfaces of the manufacturer. In case of future projects or adaptions –for example, if a new sensor was required –it would have been necessary for the manufacturer to offer this sensor. Otherwise, it was necessary to change the manufacturer, which meant that a new implementation of the software was necessary as well. In contrast, flexibility is a big advantage with Gigabit Ethernet cameras and GigE Vision: GigE Vision-compliant cameras can be used interchangeably without regard to the manufacturer.
Despite this obvious benefit, USB cameras are more prevalent in certain image processing fields like medicine, given that the applications define the camera’s sensor resolution, image format and image frequency (bandwidth), and the environment for the purpose of cable length, frame grabber, or digital camera solution. With such tightly-defined requirements, USB cameras solve the challenges of these applications.
It’s hard to believe, but a few years ago, there weren’t any standards in the image processing market. Each manufacturer had its own solution. These times are gone – the whole market has pulled together, to the benefit of customers. Because of the standards, the interaction between hardware, driver, and software delivers the experience of a uniform piece. The quality of the market is improved. For the customer, it is easier to make product decisions since they are not locked into one company’s portfolio. With standards-compliant products, the customer can always choose the best components, independent of the company. With GenICam as a base, the image processing market offers the best interface for every application, either with GigE Vision or USB3 Vision.
