X64-AN Quad User's Manual
Glossary of Terms
117
Pixel
A contraction of "picture element". The number of pixels describes the number of digital samples
taken of the analog video signal. The number of pixels per video line by the number of active video
lines describes the acquisition image resolution. The binary size of each pixel (e.g., 8-bits, 15-bits, 24-
bits) defines the number of gray levels or colors possible for each pixel.
PLL
Short for phase-locked loop. A PLL ensures that a signal is locked on a specific frequency.
Progressive Scan Camera
The progressive scan format outputs data from the camera (the signal) in sequential order as it is
scanned. The scan format produces a full frame of video in a continuous stream, rather than half the
image per output sequence in standard interlaced cameras.
Scatter Gather
Host system memory allocated for frame buffers is virtually contiguous but physically scattered
throughout all available memory.
Trigger
A mechanism that initiates an action when an event occurs such as synchronizing an image acquisition
to an external event. A trigger generally causes a program routine to be executed such as the resetting
of camera exposure and/or the firing of a strobe light.
UART
A UART (Universal Asynchronous Receiver/Transmitter) is the microchip with programming that
controls an interface to its attached serial devices.
WEN
Write ENable: Output by some video cameras to indicate valid video. Also indicates frame timing
when the camera does not use VS.
