Alpha Gradient¶
Description
Fill the alpha channel with a specified gradient (frei0r.alphagrad)[1]. Its purpose is to enable, together with alpha controlled color manipulation, the use of graduated neutral-density filters similar to what one uses in photography[2].
Parameters
Parameter |
Value |
Description |
---|---|---|
Operation |
Selection |
Defines the compositing operation |
Position |
Integer |
Position where the gradient starts (range is 0-1000, default is 500) |
Transition width |
Integer |
Width of the gradient (range is 0-1000, default is 500) |
Tilt |
Integer |
Rotation of the gradient (range is 0-1000, default is 500). Values below 500 rotate counter clockwise, values above rotate clockwise. 0 means a rotation of -180 degrees, 1000 a rotation of +180 degrees. |
Min |
Integer |
Sets the density at the bottom / start of the gradient (range is 0-1000, default is 0) |
Max |
Integer |
Sets the density at the top / end of the gradient (range is 0-1000, default is 1000) |
The following selection items are available:
Operation
Write on clear |
Overlay the image (default) |
Add |
Add the existing pixel and the calculated gradient values |
Min |
Take the minimum of existing pixel and calculated gradient values |
Max |
Take the maximum of existing pixel and calculated gradient values |
Subtract |
Subtract from the existing pixel the calculated gradient value |
Notes
In the example below a .png image has been overlayed to a video clip and the Alpha Gradient effect applied with its default values. You can see how the gradient darkens the video. Note the Operation Add to make the text opaque.