Advanced Imaging


Advanced Imaging Magazine

Updated: July 8th, 2008 05:26 PM CDT

GigE Camera Interfaces Will That Be Soft Or Hard?

Key Considerations Include Preformance, Multiple Designs, and Power Cosumption
iPORT PT1000-VB IP Engine
Pleora Technologies Inc.
The iPORT PT1000-VB IP Engine from Pleora Technologies is a high-performance, hardware-based GigE interface board designed specifically for in-camera integration.
Figure 1
Pleora Technologies Inc.
Figure 1: Imaging architectures based on cameras with hardware-based GigE interfaces have 3.5 times more processing capability than architectures based on software-based smart GigE cameras employing the PowerPC 750GX.
Figure 2
Pleora Technologies Inc.
Figure 2: The processing time per image with a hardware-based GigE architecture is at least 40% faster than with a smart GigE camera architecture.
Pleora Technologies Inc.
Performance and business trade-offs between GigE camera interfaces based on purpose-built hardware and embedded processors.

By George Chamberlain

Cameras with Gigabit Ethernet (GigE) interfaces are cropping up in imaging applications everywhere, and there is good reason for that. GigE delivers full-duplex connectivity at one gigabit per second (Gb/s) over standard, low-cost infrastructure. It has long-distance reach, supports almost any network configuration that can be envisioned, and allows heavy-duty processing tasks to be handled by scaleable stacks of economical PCs.

All GigE cameras look about the same from the back, with a RJ-45 LAN plug. But when it comes to performance, the interface electronics inside can make a world of difference.

GigE camera interfaces must perform, at minimum, six functions:

  • acquire imaging data from the camera head;
  • convert the data to IP packets;
  • queue the IP data for GigE transfer;
  • transfer the data to the IP link;
  • deliver control signals from the GigE link to the camera head; and
  • handle network functions such as boot-up and packet resend.

Basically, two design approaches can be taken to meet these requirements: build purpose-built hardware from the ground up, or write a software application for an embedded processor. Deciding which approach to take can be tricky and, in the end, usually reflects a combination of application needs and business priorities.

Hardware = Low Power, High Performance

In general, purpose-built hardware yields a high-performance, reliable GigE interface that can accommodate just about any camera sensor, including those with high resolutions and fast frame rates. Hardware interfaces operate with clock-cycle accuracy, and so perform processing tasks quickly, efficiently, and deterministically. They fit into compact footprints, important for small-body cameras.

Hardware interfaces also draw a small amount of power as low as 2.0 watts (W) and this level varies only slightly with different sensors. This is a key point, and one that gives hardware interfaces a clear advantage over software solutions, because it means camera manufacturers can use one interface to GigE-enable a wide range of cameras in their portfolios.

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