\HeaderA{make.rgb}{Create colour spaces}{make.rgb}
\aliasA{colorConverter}{make.rgb}{colorConverter}
\keyword{color}{make.rgb}
\begin{Description}\relax
These functions specify colour spaces for use in
\code{\LinkA{convertColor}{convertColor}}.
\end{Description}
\begin{Usage}
\begin{verbatim}
make.rgb(red, green, blue, name = NULL, white = "D65",
         gamma = 2.2)

colorConverter(toXYZ, fromXYZ, name, white=NULL)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{red,green,blue}] Chromaticity (xy or xyY) of RGB primaries
\item[\code{name}] Name for the colour space
\item[\code{white}] Character string specifying the reference white (see
\sQuote{Details}.)
\item[\code{gamma}] Display gamma (nonlinearity). A positive number or the
string \code{"sRGB"} 
\item[\code{fromXYZ}] Function to convert from XYZ tristimulus coordinates
to this space
\item[\code{toXYZ}] Function to convert from this space to XYZ tristimulus
coordinates.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
An RGB colour space is defined by the chromaticities of the  red, green and
blue primaries.  These are given as vectors of length 2 or 3 in xyY
coordinates (the Y component is not used and may be omitted).
The chromaticities are defined relative to a reference white, which
must be one of the CIE standard illuminants: "A", "B", "C",
"D50", "D55", "D60", "E" (usually "D65").

The display gamma is most commonly 2.2, though 1.8 is used for Apple RGB.
The sRGB standard specifies a more complicated function that is close
to a gamma of 2.2; \code{gamma="sRGB"} uses this function.

Colour spaces other than RGB can be specified directly by giving
conversions to and from XYZ tristimulus coordinates.
The functions  should take two arguments. The first is a vector giving the
coordinates for one colour. The second argument is the reference
white. If a specific reference white is included in the definition of
the colour space (as for the RGB spaces) this second argument should
be ignored and may be \code{...}.
\end{Details}
\begin{Value}
An object of class \code{colorConverter}
\end{Value}
\begin{References}\relax
Conversion algorithms from \url{http://www.brucelindbloom.com}
\end{References}
\begin{SeeAlso}\relax
\code{\LinkA{convertColor}{convertColor}}
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
(pal <- make.rgb(red=  c(0.6400,0.3300),
                 green=c(0.2900,0.6000),
                 blue= c(0.1500,0.0600),
                 name = "PAL/SECAM RGB"))

## converter for sRGB in #rrggbb format
hexcolor <- colorConverter(toXYZ = function(hex,...) {
                            rgb <- t(col2rgb(hex))/255
                            colorspaces$sRGB$toXYZ(rgb,...) },
                           fromXYZ = function(xyz,...) {
                              rgb <- colorspaces$sRGB$fromXYZ(xyz,..)
                              rgb <- round(rgb,5)
                              if (min(rgb) < 0 || max(rgb) > 1)
                                   as.character(NA)
                              else
                                   rgb(rgb[1],rgb[2],rgb[3])},
                           white = "D65", name = "#rrggbb")

(cols <- t(col2rgb(palette())))
(luv <- convertColor(cols,from="sRGB", to="Luv", scale.in=255))
(hex <- convertColor(luv, from="Luv",  to=hexcolor, scale.out=NULL))

## must make hex a matrix before using it
(cc <- round(convertColor(as.matrix(hex), from= hexcolor, to= "sRGB",
                          scale.in=NULL, scale.out=255)))
stopifnot(cc == cols)
\end{ExampleCode}
\end{Examples}

