Set brightness, contrast, saturation and approximate gamma adjustment.

The filter accepts the following options:

contrast

Set the contrast expression. The value must be a float value in range -2.0 to 2.0. The default value is "1".

brightness

Set the brightness expression. The value must be a float value in range -1.0 to 1.0. The default value is "0".

saturation

Set the saturation expression. The value must be a float in range 0.0 to 3.0. The default value is "1".

gamma

Set the gamma expression. The value must be a float in range 0.1 to 10.0. The default value is "1".

gamma_r

Set the gamma expression for red. The value must be a float in range 0.1 to 10.0. The default value is "1".

gamma_g

Set the gamma expression for green. The value must be a float in range 0.1 to 10.0. The default value is "1".

gamma_b

Set the gamma expression for blue. The value must be a float in range 0.1 to 10.0. The default value is "1".

gamma_weight

Set the gamma weight expression. It can be used to reduce the effect of a high gamma value on bright image areas, e.g. keep them from getting overamplified and just plain white. The value must be a float in range 0.0 to 1.0. A value of 0.0 turns the gamma correction all the way down while 1.0 leaves it at its full strength. Default is "1".

eval

Set when the expressions for brightness, contrast, saturation and gamma expressions are evaluated.

It accepts the following values:

init

only evaluate expressions once during the filter initialization or when a command is processed

frame

evaluate expressions for each incoming frame

Default value is init.

The expressions accept the following parameters:

n

frame count of the input frame starting from 0

pos

byte position of the corresponding packet in the input file, NAN if unspecified

r

frame rate of the input video, NAN if the input frame rate is unknown

t

timestamp expressed in seconds, NAN if the input timestamp is unknown