58 of 73
Reference Manual ATOM one 4K mini
linear part by the following formula:
V
out, linear max
≈
V
out, non-linear min
Brightness
non-linear
≈(
Contrast
linear
∗
threshold
+
Brightness
linear
)−
Contrast
non-inear
∗
threshold
Gamma
Example Pseudo Code to setup a REC.709 gamma curve:
float threshold
= 0.018;
float linear_contrast
= 4.5f;
float linear_brightness
= 0.0f;
float gamma
= 0.45f;
float contras
= 1.099f;
float brightness
= -0.099f;
int t = (int) round( threshold * 1000.0f );
// t = 18
int lc = (int) round( linear_contrast * 1000.0f );
// lc = 4500
int lb = (int) round( linear_brightness * 1000.0f );
// lb = 0
int c = (int) round( contrast * 1000.0f );
// c = 1099
int g = (int) round( linear_contrast * 1000.0f );
// g = 450
int b = (int) round( brightness * 1000.0f );
// b = -99
Example curve for REC.709:
=> lut_gamma 18 4500 0 1099 450 -99
OK
12.18
lut_fast_gamma <gamma>
The fast gamma function uses the same formula as the
lut_fun_rec709
command, but the
user only has to specify the desired gamma value. All other values are fixed or computed
as needed.
Value
Minimal
Maximal
REC.709
Gamma
1100
3000
2222
Note: The value is normalized to a range from 0.0 to 1.0 and multiplied by a scaling
coefficient of 1000. Setting a value of 2222 will result in the default REC.709 gamma
curve.
12.19
lut_fixed_mode <mode>
The fixed gamma mode allows to choose between three fixed gamma tables which are
