Advanced Imaging


Advanced Imaging Magazine

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

The Migration to Digital from Analog Cameras

Fig. 1. Frame integration mode of interlaced sensors - high sensitivity.
Pictured is the new series of interlaced digital cameras from Allied Vision Technologies. This family, known as the Guppy Interlaced series, is based on the IEEE1394 Firewire digital bus allowing for easy integration into vision systems.

By Michael Cyros President, Allied Vision Technologies, Inc.

With the introduction of industrial digital cameras for the machine vision and scientific imaging markets nearly 20 years ago, why is it that the majority of cameras used in vision systems last year continue to be based on analog cameras? Especially since digital cameras promise to deliver higher quality images, faster data rates, more frames per second and eliminate or minimize the need for a frame grabber.

Digital standards such as IEEE 1394 Firewire, CameraLink and GigE Vision provide the vision system manufacturer or integrator with a wide range of digital cameras from several manufacturers boasting compatible functionality. Yet, many reach for sole-sourced older analog cameras. What are the reasons for this? Will this change in the future?

In the Automated Imaging Association's Machine Vision Markets-2005 Results and Forecasts to 2010, it is reported that 65 percent of all cameras units sold in North America were analog. Interestingly, these analog cameras accounted for only 45.5 percent of the total revenues. This clearly indicates the obvious point that analog cameras are relatively low cost compared to digital cameras.

Digital camera producers have tried to tap this lower end of the market by producing a range of both CCD and CMOS based cameras that are approaching the price range of analog cameras. Further, consider that an analog camera must be coupled with a frame grabber to digitize the image and provide it to PC memory for processing. Certainly, the cost of the frame grabber plus the camera is now starting to be equalized by digital cameras. Digital cameras are also providing in-camera functionality such as I/O, look up tables and exposure control that used to be only a prime function of the frame grabber.

It is generally the case that most new systems designs are based on digital cameras, while analog camera sales are concentrated largely in ongoing legacy systems production. This indicates that the reason for the lack of a majority conversion from analog to digital isn't only based on price.

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