\HeaderA{kooperberg}{Kooperberg Model-Based Background Correction}{kooperberg}
\keyword{models}{kooperberg}
\begin{Description}\relax
This function uses a Bayesian model to 
background correct GenePix microarray data.
\end{Description}
\begin{Usage}
\begin{verbatim}
kooperberg(RG, a=TRUE, layout=RG$printer, verbose=TRUE)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{RG}] an RGList of GenePix data, read in using \code{read.maimages}, with \code{other.columns=c("F635 SD","B635 SD","F532 SD","B532 SD","B532 Mean","B635 Mean","F Pixels","B Pixels")}.
\item[\code{a}] logical.  If \code{TRUE}, the 'a' parameters in the model (equation 3 and 4) are estimated for each slide.  If \code{FALSE} the 'a' parameters are set to unity.
\item[\code{layout}] list containing print layout with components \code{ngrid.r}, \code{ngrid.c}, \code{nspot.r} and \code{nspot.c}.  Defaults to \code{RG\$printer}.
\item[\code{verbose}] logical.  If \code{TRUE}, progress is reported to standard output.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
This function is for use with GenePix data and is designed to cope with the problem of large numbers of negative intensities and hence missing values on the log-intensity scale.
It avoids missing values in most cases and at the same time dampens down the variability of log-ratios for low intensity spots.
See Kooperberg et al (2002) for more details.

\code{kooperberg} uses the foreground and background intensities, standard
deviations and number of pixels to compute empirical estimates of the model 
parameters as described in equation 2 of Kooperberg et al (2002).
\end{Details}
\begin{Value}
An \code{RGList} containing the components
\begin{ldescription}
\item[\code{R}] matrix containing the background adjusted intensities for
the red channel for each spot for each array
\item[\code{G}] matrix containing the background adjusted intensities for the green channel for each spot for each array
\item[\code{printer}] list containing print layout
\end{ldescription}
\end{Value}
\begin{Author}\relax
Matthew Ritchie
\end{Author}
\begin{References}\relax
Kooperberg, C., Fazzio, T. G., Delrow, J. J., and Tsukiyama, T. (2002)
Improved background correction for spotted DNA microarrays.
\emph{Journal of Computational Biology} \bold{9}, 55-66.
\end{References}
\begin{SeeAlso}\relax
\LinkA{04.Background}{04.Background} gives an overview of background correction functions defined in the LIMMA package.
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
#  This is example code for reading and background correcting GenePix data
#  given GenePix Results (gpr) files in the working directory (data not
#  provided).
## Not run: 
genepixFiles <- dir(pattern="*\\.gpr$") # get the names of the GenePix image analysis output files in the current directory
RG <- read.maimages(genepixFiles, source="genepix", other.columns=c("F635 SD","B635 SD","F532 SD","B532 SD","B532 Mean","B635 Mean","F Pixels","B Pixels"))
RGmodel <- kooperberg(RG)
MA <- normalizeWithinArrays(RGmodel)
## End(Not run)
\end{ExampleCode}
\end{Examples}