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TV Camera or Vidicon Tube
A first choice for a two-dimensional image input device
may be a television camera -- output is a video signal:
- Image focused onto a
- Target scanned line
by line horizontally by an electron beam
- Electric current produces as the beam passes over target.
- Current proportional to the intensity of light at each
- Tap current to give a video signal.
This form of device has several disadvantages.
- Limited resolution
- -- finite number of scan lines (about
625) and frame rate (30 or 60 frames per second)
persistence between one frame and the next
- Non-linear video output with respect to light intensity.
- Non-flat target on tube.
By far the most popular two-dimensional imaging device
is the charge-coupled device (CCD) camera.
- Single IC device
- Consists of an array of photosensitive
- each cell produces an electric current dependent on
the incident light falling on it.
- Video Signal Output
- Less geometric distortion
- More linear Video output.
David Marshall 1994-1997