SVS-Vistek 926.15hr387*XGE Series, User Manual

Page: 19 / 122

SVS-VISTEK
Feature description 19
5.1.4 Acquisition and Processing Time
The camera has to read the sensor, process the data to a valid image
and transfer this to the host computer. Some of these tasks are done in
parallel. This implies the data transfer does not end immediately after end
of exposure, as the image has to be processed and transferred after
exposure.
On the other side, while processing and transferring the image the sensor
might capture already the next frame.
5.1.5 Auto exposure
Auto Luminance or auto exposure automatically calculates and adjusts
exposure time and gain, frame-by-frame.
The auto exposure or automatic luminance control of the camera signal is
a combination of an automatic adjustment of the camera exposure time
(electronic shutter) and the gain.
The first priority is to adjust the exposure time and if the exposure time
range is not sufficient, gain adjustment is applied. It is possibility to pre-
define the range (min. / max. -values) of exposure time and of gain.
The condition to use this function is to set a targeted averaged brightness
of the camera image. The algorithm computes a gain and exposure for
each image to reach this target brightness in the next image (control
loop). Enabling this functionality uses always both – gain and exposure
time.
Limitation
As this feature is based on a control loop, the result is only useful in an
averaged, continuous stream of images. Strong variations in brightness
from one image to next image will result in a swing of the control loop.
Therefore it is not recommended to use the auto-luminance function in
such cases.
5.1.6 Bit-Depth
Values of brightness are internally represented by numbers. The number
of bits for brightness representation is limiting the number of colour values
that can be represented. Bit depth defines the maximum unique colors or
grey levels in an image.
No of grey values = 2
bit depth
All SVCam models support 8-bit format. In most cases, the sensor itself is
limiting maximum bit depth. Refer to specifications whether your model is
supporting higher bit depth.