Photon Focus DR1-D3360-192-G2-8, User Manual, Page: 55 / 119

5.3 Multiple Slope Mode (High Dynamic Range)
The Multiple Slope High Dynamic Range (HDR) mode is a special integration mode that
increases the dynamic range of the pixels, and thus avoids the saturation of the pixels in many
cases. The multiple slope mode is also called multiple slope mode or piecewise linear mode.
The multiple slope mode clips illuminated pixels which reach a programmable voltage, while
leaving the darker pixels untouched (see Fig. 5.27). The clipping level can be adjusted once (2
slopes) or twice (3 slopes) within the exposure time.
Parameters:
Multislope_Mode There are 3 predefined multiple slope parameter sets:
LowCompression
,
NormalCompression
and
HighCompression
. If
Multislope_Mode
is set to
UserDefined
then the
individual parameters can be set to user defined values.
Multislope_NrSlopes Number of slopes. Multislope_NrSlopes =2: 2 slopes with only kneepoint B.
Multislope_NrSlopes =3: 3 slopes with kneepoints A and B.
Multislope_Value1 Corresponds to Vlow1: the higher the value, the higher the compression.
Multislope_Time1 Time corresponding to kneepoint B. The value is the fraction (per mill) of
the total exposure time.
Multislope_Value2 Corresponds to Vlow2: the higher the value, the higher the compression.
This value is ignored if Multislope_NrSlopes =2.
Multislope_Time2 Time corresponding to kneepoint A. The value is the fraction (per mill) of
the total exposure time. This value is ignored if
Multislope_NrSlopes
=2.
The red line in Fig. 5.27 shows a pixel with high illumination. Without the multiple slope
mode, the pixel would have reached its saturated value. With multiple slope mode, the pixel
reaches value P1 which is below the saturation value. The resulting pixel response in this case is
shown in Fig. 5.28. The blue line (P2) shows a pixel with low illumination. Its value never
reaches Vlow2 or Vlow1 at the kneepoints and the resulting response is linear.
The parameters Multislope_Value1 and Multislope_Value2 are only applied after
a camera trigger. Note that in free-running mode the camera trigger is applied
internally by the camera itself.
5.3 Multiple Slope Mode (High Dynamic Range) 55