hue

Modify the hue and/or the saturation of the input.

It accepts the following parameters:

'h': Specify the hue angle as a number of degrees. It accepts an expression, and defaults to "0".
's': Specify the saturation in the [-10,10] range. It accepts an expression and defaults to "1".
'H': Specify the hue angle as a number of radians. It accepts an expression, and defaults to "0".
'b': Specify the brightness in the [-10,10] range. It accepts an expression and defaults to "0".

'h' and 'H' are mutually exclusive, and can't be specified at the same time.

The 'b', 'h', 'H' and 's' option values are expressions containing the following constants:

'n': frame count of the input frame starting from 0
'pts': presentation timestamp of the input frame expressed in time base units
'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
'tb': time base of the input video

Command line examples

Set the hue to 90 degrees and the saturation to 1.0:
```
hue=h=90:s=1
```
Same command but expressing the hue in radians:
```
hue=H=PI/2:s=1
```
Rotate hue and make the saturation swing between 0 and 2 over a period of 1 second:
```
hue="H=2*PI*t: s=sin(2*PI*t)+1"
```
Apply a 3 seconds saturation fade-in effect starting at 0:
```
hue="s=min(t/3\,1)"
```
The general fade-in expression can be written as:
```
hue="s=min(0\, max((t-START)/DURATION\, 1))"
```
Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
```
hue="s=max(0\, min(1\, (8-t)/3))"
```
The general fade-out expression can be written as:
```
hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
```

This filter supports the following commands:

'b'

's'

'h'

'H'

Modify the hue and/or the saturation and/or brightness of the input video. The command accepts the same syntax of the corresponding option.

If the specified expression is not valid, it is kept at its current value.