Baumer VCXG .I - Look-Up-Table and Gamma Correction; Look-Up-Table Functionality; Gamma Correction for Light Perception

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7.1.5 Look-Up-Table
The Look-Up-Table (LUT) is employed on Baumer monochrome and color cameras. It
contains 2
12
(4096) values for the available levels. These values can be adjusted by the
user.
For color cameras the LUT is applied for all color channels together.
7.1.6 Gamma Correction
With this feature, Baumer VCX cameras offer the possibility of compensating nonlinearity
in the perception of light by the human eye.
For this correction, the corrected pixel intensity (Y') is calculated from the original intensity
of the sensor's pixel (Y
original
) and correction factor γ using the following formula (in over-
simplied version):
Y' = Y
original
γ
On Baumer VCX cameras the correction factor γ is adjustable from 0.1 to 2.
The values of the calculated intensities are entered into the Look-Up-Table. Thereby pre-
viously existing values within the LUT will be overwritten.
Notice
If the LUT feature is disabled on the software side, the gamma correction feature is
disabled, too.
Notice
For cameras with long readout times (e.g.: VCXU-201M.R / VCXU-123M) may cause
visual effects while setting a value for gamma and simultaneous image acquisition, be-
cause access to LUT is not locked against the pixel stream.
This can be prevented by stopping the camera (AcquisitionStop) before setting.
H
E0
▲Figure26
Non-linear perception of
the human eye.
H - Perception of bright-
ness
E - Energy of light