Gamma Correction - Basler ace acA640-90gm User Manual

Color Creation and Enhancement
To set the Balance Ratio parameter for a color:
Set the Balance Ratio Selector to red, green, or blue.
Set the Balance Ratio Abs parameter to the desired value for the selected color.
You can set the Balance Ratio Selector and the Balance Ratio Abs parameter value from within your
application software by using the Basler pylon API. The following code snippet illustrates using the
API to set the selector and the parameter value:
Camera.BalanceRatioSelector.SetValue( BalanceRatioSelector_Green );
Camera.BalanceRatioAbs.SetValue( 1.20 );
You can also use the Basler pylon Viewer application to easily set the parameters.
For more information about the pylon API and the pylon Viewer, see Section 3 on
8.4.2

Gamma Correction

The gamma correction feature lets you modify the brightness of the pixel values output by the
camera's sensor to account for a non-linearity in the human perception of brightness. There are two
modes of gamma correction available on the camera: sRGB and User.
sRGB Gamma
When the camera is set for sRGB gamma correction, it automatically sets the gamma correction to
adjust the pixel values so that they are suitable for display on an sRGB monitor. If you will be
displaying the images on an sRGB monitor, using this type of gamma correction is appropriate.
User Gamma
With User type gamma correction, you can set the gamma correction value as desired.
To accomplish the correction, a gamma correction value (γ) is applied to the brightness value (Y) of
each pixel according to the following formula:
Y
⎛
uncorrected
-------------------------- -
Y =
⎝
corrected
Y
The formula uses uncorrected and corrected pixel brightnesses that are normalized by the
maximum pixel brightness. The maximum pixel brightness equals 255 for 8 bit output and 4095 for
12 bit output.
The gamma correction value can be set in a range from 0 to 3.99902.
When the gamma correction value is set to 1, the output pixel brightness will not be corrected.
148
γ
⎞
×
Y
⎠
max
max
page 27.
Basler ace GigE