Chroma and luma keying – spill correction
Functions in the Spill Correction section eliminate from the object a reflection effect of the keyed background color. The picture below shows an impact of green color on the object – view before the spill correction.
Click on the icon Spill Correction to open the spill correction window. Despill Color and Despill Coarse functions are the functions used for preliminary elimination of unwanted color on the basis of RGB (red, green, blue) plane.
When you move the Despill Color slider to position 0 (to the left), the algorithm will automatically subtract the green color component, in the case when green is a keyed color (similarly blue when a blue background is used). Whereas moving it to a position 1000 (to the right) will cause adding color red with blue (when green is a keyed color) or red with green (in the case when a blue background was used) automatically by the algorithm.
You can control the value of the algorithm with Despill Coarse function. In the case of green background color, the Despill Coarse function entirely excludes a green component from the object in the RGB (red, green, blue) plane when it goes beyond a certain threshold, resulting in a shift of color to the purple
The next function enables more accurate improvement of the correction described above.
When you use the Despill Fine function, the color of the keyed background is excluded, but this time on the basis of chrominance components. Below you can see the Despill Fine slider.
After using the Despill Coarse function, which is an initial correction, the next step is to operate on the precise values. In the case where the Despill Coarse function was set at a high level, any changes in Despill Fine function settings may be of little significance to the algorithm.