13.14 LUT Control 121
mvLUTType Describes which type of LUT is
used for the current LUTSelector
mvLUTInputData Describes the data the LUT is ap-
plied to (e.g bayer, RGB, or gray
data)
mvLUTMapping Describes the LUT mapping (e.←-
g. 10 bit -> 12 bit)
related to the look-up table (LUT) control.
The look-up table (LUT) is a part of the signal path in the camera and maps data of the ADC into signal values. The
LUT can be used e.g. for:
• High precision gamma
• Non linear enhancement (e.g. S-Shaped)
• Inversion (default)
• Negative offset
• Threshold
• Level windows
• Binarization
This saves (approx. 5%) CPU load, works on the fly in the FPGA of camera, is less noisy and there are no missing
codes after Gamma stretching. Three read-only registers describe the LUT that is selected using the LUTSelector
register:
13.14.1 mvLUTType
There are two different types of LUTs available in MATRIX VISION cameras: Direct LUTs define a mapping for each
possible input value, for example a 12 -> 10 bit direct LUT has 2
∧
12 entries and each entry has 10 bit. Interpolated
LUTs do not define a mapping for every possible input value, instead the user defines an output value for equidistant
nodes. In between the nodes linear interpolation is used to calculate the correct output value. Considering a 10
-> 10 bit interpolated LUT with 256 nodes (as usually used in MATRIX VISION cameras), the user defines a 10
bit output value for 256 equidistant nodes beginning at input value 0, 4, 8, 12, 16 and so on. For input values in
between the nodes linear interpolation is used.
13.14.2 mvLUTInputData
This register describes on which data the LUT is applied to: Bayer means that the LUT is applied to raw bayer
data, thus (depending on the debayer algorithm) a manipulation of one pixel may also affect other pixels in its
neighborhood Gray means that the LUT is applied to gray data RGB means that the LUT is applied to RGB data
(i.e. after debayering). Normally this is used to change the luminance on an RGB image and the LUT is applied to
all three channels.
13.14.3 mvLUTMapping
This register describes the mapping of the currently selected LUT, e.g "map_10To10" means that a 10 bit input value
is mapped to a 10 bit output values whereas "map_12To10" means that a 12 bit input value is mapped to a 10 bit
output value.
13.14.4 LUT support in MATRIX VISION cameras
MATRIX VISION GmbH
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