The Keying > Cross Keyer effect

The Keying > Cross Keyer effect works in a different way than the other keying effects :
It doesn't require to select a range of colors in a color system like RGB, HSL, YUV, etc ...
In this effect, you only need to define a first region whose colors will be kept, and another region whose colors will become transparent.

Selecting those two regions can be easily done thanks to the two dedicated Region buttons :
* To select the colors you want to keep after applying the FX, just use the left mouse button on the Keep button. After this you will be able to select an area directly on the HUD. (your cursor will be changed into a lasso)
* To select the colors which will become transparent, you can use the same method with the Drop button.

When selecting a new area on the HUD :
* Use the left mouse button to add it to the previously selected area.
* Use the right mouse button to subtract it from the previously selected area.

To visualize the render of this effect, use the right (or left) mouse button on the current activated button (Keep or Drop). Of course, the result depends on the two areas you have just selected.

In the example below :
On the left : there are two areas located on the sky and on the pathway. They indicate the colors (red and cyan) that will be kept on the whole picture.
At the center : there is one area located on the grass and on the trees. It indicates the colors (orange and green) that will be dropped.
The picture on the right shows the result after applying the effect :

Keep regionDrop regionFinal result

* The Swap keep and drop regions button allows to swap the Keep and Drop regions.
It is then possible to obtain the opposite result.

* The Mix parameter allows to extend or restrict the number of colors located in the transparent area of the resulting image.

Mix = 0%Mix = 50%Mix = 100%

* The Edge parameter allows to adjust the mixing level between the transparent and opaque pixels.
The lower the value will be, the less the two regions will differentiate. The higher the value will be, the sharper the edges will appear.

Edge = 0%Edge = 50%Edge = 100%

* The Spill Removal parameter has the same function as the Spill Removal parameters encountered in the effect Keying > Chroma Keyer : it unsaturates the undesired light reflections.
In the example below, we zoomed on the frontier between the grass and the pathway.

Source ImageSpill Removal = 0%Spill Removal = 100%