Gain - Photon Focus MV4 Series User Manual

mapped to 256 output grey levels. The use of the three available modes is explained in the next
sections. Two LUT and a Region-LUT feature are available in the camera (see Section 12.4.4).
The LUT is implemented as a 12-to-8 bit LUT to be compatible with other Photon-
focus cameras. Bits 0 & 1 of the 12 bit LUT input data are set to random values.
The output grey level resolution of the look-up table (independent of gain,
gamma or user-definded mode) is always 8 bit.
There are 2 predefined functions, which generate a look-up table and transfer it
to the camera. For other transfer functions the user can define his own LUT file.
Some commonly used transfer curves are shown in Fig. 12.6. Line a denotes a negative or
inverse transformation, line b enhances the image contrast between grey values x0 and x1.
Line c shows brightness thresholding and the result is an image with only black and white grey
levels. and line d applies a gamma correction (see also Section 12.4.2).
Figure 12.6: Commonly used LUT transfer curves

12.4.1 Gain

The 'Gain' mode performs a digital, linear amplification with clamping (see Fig. 12.7). It is
configurable in the range from 1.0 to 4.0 (e.g. 1.234).
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y = f ( x )
y
m a x
d
12.4 Grey Level Transformation (LUT)
c
b
=
x x
0 1
x
x
m a x
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