User`s manual

Preliminary
Genie Monochrome Series-GigE Vision Camera Operational Reference • 35
Gain and Black Level Controls
The Genie series of monochrome cameras provide gain and black level adjustments for the analog
signal from each CCD pixel, before the analog to digital conversion. The software gain and black level
controls can make small compensations to the acquisition in situations where lighting varies and the
lens iris can not be easily adjusted. The user can evaluate Gain and Black Level by using CamExpert.
Features and limitations are described below.
• Gain is expressed in decibels (dB). Range from -6dB to +12dB in 0.1dB increments. Gain is a
multiplication factor to the analog signal before digitization.
• Increasing gain increases the amplitude of the analog video signal but also increases the sensor
analog noise proportionately, before analog to digital conversion. An increase of 6dB doubles the
signal intensity.
• Black level is applied to the sensor analog signal to shift the DC level of the video signal. Black
level is an additive offset to the analog video signal before digitization.
• Black level increases the brightness of the video signal equally. Therefore any area of the video
that is black will brighten to some gray level as offset is increased.
• Black level is expressed as a number ranging from -128 to 127. The offset is achieved as a change
in the analog signal from the sensor where a control number change of 1 is 1/16
th
of a DN (digital
number) pixel change. In other words, a control change of 16 is required for each change in pixel
value, therefore a maximum control value of 127 will cause a black pixel (00) to have a gray value
of about 8.
Gain and Offset Control via Sapera LT or GenICam
Applications
Genie Sapera parameters for Gain and Black level:
Gain = Amplification in dB from -6.0 to 12.0 dB
BlackLevel = DC offset in 1/16
th
of DN, range from -128 to 127
In CamExpert, these parameters are available under the “Sensor” tab.
GenICam features for Gain and Black level:
GainRaw = Analog gain in tenth of dB (0.1 dB)
BlackLevelRaw = Black level (offset) in 1/16 of DN