Kdenlive/Руководство/Эффекты/Обработка альфа-канала/Хромакей:расширенный (выбор цвета)
Color Selection
This is the FilterFrei0r-select0r filter
This is color based alpha selection. For example, this offers you a blue screen/green screen/chroma-keying effect.
Selection Subspace options are: RGB (Red Green Blue), ABI and HCL (hue, chroma and luminance)
Subspace Shape options are: Box, Ellipsoid, Diamond
Edge Mode Options are: Hard, Fat, Normal, Skinny, Slope
Operation options are: Write On Clear, Max, Min, Add and Subtract. This defines how to deal with an existing alpha channel in the clip. See Alpha Shapes for the meanings of these operations.
See Also
See also Blue Screen which does color based alpha selection but is a bit simpler.
This page covers some Color Theory to help understand Hue, Chroma, Luminance etc.