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.
Alpha Gradient effect - before¶
Alpha Gradient effect - after¶