\HeaderA{hullFeatures}{Extraction of hull features from images of indexed objects}{hullFeatures}
\aliasA{hullFeatures,IndexedImage-method}{hullFeatures}{hullFeatures,IndexedImage.Rdash.method}
\keyword{manip}{hullFeatures}
\begin{Description}\relax
Hull features are a set of numeric descriptors of the hull of an object. These
include coordinates, perimeter, size, acircularity etc.
\end{Description}
\begin{Usage}
\begin{verbatim}

  ## S4 method for signature 'IndexedImage':
  hullFeatures(x, ...)
  
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{x}] An object of \code{\LinkA{IndexedImage}{IndexedImage.Rdash.class}}.
\item[\code{...}] Reserved. 
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
The extracted features are (names carry an \code{h.} prefix to indicate hull
features): \code{x,y} - coordinates of the geometric center, \code{s} - size (area),
\code{p} - perimeter, \code{pdm} - mean distance to perimeter (from the center),
\code{pdsd} - standard deviation of the distance to perimeter, \code{effr} - 
effective radius (is the radius of a circle with the same area), \code{acirc} -
acircularity (fraction of pixels outside of the circle with \code{r=reff}), 
\code{sf} - shape factor (\code{per / ( 2 * sqrt(Pi * s))}), \code{edge} - 
number of pixels at the edge of the image, \code{theta} - hull's rotation
angle (calculated without taking intensity values into account), \code{s2maj} -
2 times semi major (square root of the larger eigenvalue of the 
\code{\LinkA{moments}{moments}} covariance matrix) - correlates with the distance from
the center to the edge along the major axis, \code{s2min} - same but for the 
smaller eigenvalue (minor axis), \code{ecc} - eccentricity 
(\code{sqrt(eig1-eig2)/smaj}), \code{I1, I2} - first and second rotation invariant
moments of the hull (as in \code{\LinkA{moments}{moments}}).
\end{Details}
\begin{Value}
For a single frame, a matrix of descriptors with objects in rows and features
in columns. For image stacks, a list of such matrices.
\end{Value}
\begin{Author}\relax
Oleg Sklyar, \email{osklyar@ebi.ac.uk}, 2007
\end{Author}
\begin{SeeAlso}\relax
\code{
  \LinkA{IndexedImage}{IndexedImage.Rdash.class}, \LinkA{IndexedImage}{IndexedImage.Rdash.class}, \LinkA{IndexedImage}{IndexedImage.Rdash.class}, 
  \LinkA{IndexedImage}{IndexedImage.Rdash.class}, \LinkA{IndexedImage}{IndexedImage.Rdash.class}
}
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
  ## see example(getFeatures)
\end{ExampleCode}
\end{Examples}

