\subsection[Chroma Key (HSV)]{Chroma Key (HSV)}%
\label{sub:chroma_key_hsv}
\index{chroma key HSV}

Chroma Key (HSV)\protect\footnote{Credit for Plugin by Jerome Cornet \url{http://jcornet.free.fr/linux/chromakey.html}} (figure~\ref{fig:chroma-key-hsv}) replaces a color with another color or transparency using HSV variables; By now this plugin is replaced by the better Chroma Key (Avid) and is maintained only for reasons of compatibility with old projects.
Refer to the latter for theory and parameter descriptions (Which are similar). That remains the description of spill suppression, which differs considerably.

\begin{figure}[htpb]
	\centering
	\includegraphics[width=0.55\linewidth]{chroma-key-hsv.png}
	\caption{Windows config for Chroma Key (HSV)}
	\label{fig:chroma-key-hsv}
\end{figure}

\qquad \textit{Spill light control section}

In this section we try to make halos, reflections and parasitic lights present on the foreground less noticeable.

\begin{description}
	\item[spill light control:] This step helps you remove the green or blue halo around the edges of the mask. It does so by removing the saturation of pixels of the foreground that have a similar hue to the key color (turning them into grey instead of green or blue). The hues to be desaturated are set with \textit{Spill Threshold}, the degree of desaturation is set with \textit{Spill Compensation}. In order for Spill compensation to work, Spill Threshold must be > 0. If you start with Spill Compensation at $100\%$, slowly increase the \textit{Spill Threshold} until the remaining green or blue areas turn grey. Then reduce Spill Compensation until the image looks good.
\end{description}


