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Reference Manual ATOM one SSM500
13.17
lut_fun_rec709 <threshold> <linear-contrast> <linear-
brightness> <contrast> <gamma> <brightness>
Sets sample points according to REC.709 for the current LUT.
Existing sample points will be cleared before run.
Sets the gamma curve for all 3 colors.
If the gamma curve is set with this function,
save_settings
will start the system with this
values on boot up.
Value
Minimal
Maximal
REC.709
Threshold
0
1000
18
Contrast (linear)
0
10000
4500
Brightness (linear)
-1000
1000
0
Contrast (non-linear)
0
10000
1099
Gamma (non-linear)
0
1000
450
Brightness (non-
linear)
-1000
1000
-99
Note: The values are normalized to a range from 0.0 to 1.0 and multiplied by a scaling
coefficient of 1000.
The following image shows the normalized REC.709 gamma curve and it's transition from
linear to non-linear (power function) part.
The linear part ranges from 0 to <0.018 and is computed by the following formula:
V
out
=
4.5
∗
V
in
The maximum value in this range is:
V
out,min
=
lim
V
in
→
0.018
(
4.5
∗
V
in
)=
4.5
∗
0.018
=
0.081
The non-linear part ranges from 0.018 to 1 and is computed by the following formula:
V
out
=
1.099
∗
V
in
0.45
−
0.099
The minimum value in this range is:
V
out,min
=
1.099
∗
0.018
0.45
−
0.099
=
0.081 ...
