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The choice
of an analog video camera or digital one comes down to three main factors -
display refresh rate, compatibility and cost. Since microscopy is highly
interactive it is important to have the human interface be a close to
"realtime" as possible. "Realtime" has come to mean 25
to 30 frames per second (even motion pictures are 24 frame per second). The
number is related to visual physiology - the critical flicker rate, the
rate above which the image is perceived as being continuously presented.
Until quite recently only true analog video cameras were capable of
presenting data that quickly. NTSC analog video, when digitized is almost
30MB per second. Since the video standards are so widely accepted it is a
simple matter to find compatible hardware a situation that does not yet
exist in the digital image world where many imaging devices use interfaces
that are far less common. Except for the NTSC/PAL dichotomy, a video
recording made on one machine is certain to play on any other comparable
machine. Until quite recently, digital cameras with a resolution higher
than analog video (640x480) that had a 30 frame per second output were
quite expensive. Our new KH-1300/7700, however has overcome many of the
limitation previously encountered in streaming digital imaging. With a
standard UXGA (1600x1200) output, the camera can plug directly into a high
resolution computer monitor. What’s more, with new pixel shifting
technology the field of view can be sub-pixel sampled to give images with
30million pixels. Even recording streaming digital signals is now a
simple matter with the latest compression codecs.
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