Understanding ispeed
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i--SPEED LT, i--SPEED 2
` Dynamic Range
The human eye has an extraordinary ability to see dark and bright
objects simultaneously. The classical illustration of this is a plant
on a windowsill. The eye can see the plant and the view through
the window simultaneously. Ordinary video cameras are less
capable and can only produce images of one or the other. Either
the plant will be a featureless black silhouette and the view through
the window will be visible or the plant will be visible and the view
through the window will be a featureless white sheet.
The level of ability to see light and dark simultaneously is called
dynamic range.
The i-- SPEED LT, i-- SPEED 2 ’s image sensor is capable of
increasing its dynamic range by detecting light in a non--linear
fashion. This permits each pixel to individually reduce its sensitivity
with increasing light. This effect allows the sensor to gather image
features in very bright and dark areas simultaneously and this
process is known as “dynamic range extension”.
` Internal Memory, Circular buffer
When in record mode, the c amera continuously stores frames in its
internal memory. That memory is configured in a circle so that,
once the memory is full, each new frame replaces the oldest stored
frame. In this way, the camera keeps a rolling history of the scene
it views and this process can continue indefinitely. This
configuration of the memory is called a “circular buffer”.
Once the desired event has occurred, the camera may be stopped
by pressing a menu button or raising a trigger event as discussed
below.
` Trigger
As mentioned above, the Olympus i-- SPEED LT, i-- SPEED 2
records video in a circular buffer and can do so indefinitely. At
some point, however, it is necessary to stop the recording process
in order to preserve the data in the memory.
The method of stopping the camera is highly important as it is this
which guarantees the capture of the event in question. There are
two methods of stopping the Olympus i-- SPEED LT, i-- SPEED 2 .
The first is a button press in the menu system and this immediately
stops the record process, so that the memory contains the history
prior to the button press.
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