Faber M1024, M640, M1600, M1400 user manual Gain and Black Level Controls

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 (i.e. exposure) before digitization.

Note that a gain of 6dB is a multiplier of 2 (doubles the level).

• Increasing gain increases the amplitude of the analog video signal but also increases the sensor analog noise proportionately, before analog to digital conversion.

• Note: Doubling gain does not necessarily double the digital data due to the Black Level Offset value as described below.

• Black level offset 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 offset 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 offset 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 1/16th 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.

• The resultant output Gain/Offset formula is OutputData = (Exposure * Gain) + Offset

where : Gain = 20log(multiplier)

Gain and Offset Control via Sapera LT or GenICam Applications

Sapera

Genie Sapera parameters for Gain and Black level:

Gain = Amplification in dB from -6.0 to 12.0 dB

BlackLevel = DC offset in 1/16th of DN, range from -128 to 127

In CamExpert, these parameters are available under the “Sensor” tab. See "Accessing Features with Sapera++ LT" on page 68.

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

36 • Operational Reference Genie Monochrome Series-GigE Vision Camera