Advanced Imaging

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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.
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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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