I've put together a rough R port of that C code [*] in a package on r-
forge:
http://r-forge.r-project.org/plugins/scmsvn/viewcvs.php/pkg/spectral/?root=photonics
http://r-forge.r-project.org/R/?group_id=160 ( package spectral, will
be built overnight )
There is a lot of optimization and cleaning to do: it seems much
slower than it should be, and the documentation is empty at the
moment, but it reproduces the result for the black body radiation.
library(spectral)
data(wavelength)
data(cie_colour_match)
data(colourSystem)
test <- function(bbTemp=5000){
mxyz <- spectrum_to_xyz(specfun=bb_spectrum, bbTemp=bbTemp)
rgb <- xyz_to_rgb(colourSystem[3, ], mxyz)
norm_rgb(constrain_rgb(rgb))
}
temperatures <- seq(1000, 10000, by=500)
# temperatures <- seq(1000, 10000, length=300)
res <- abs(sapply(temperatures, test))
grid.newpage()
start <- seq(0.1, 0.9, length=dim(res)[2])
end <- start + mean(diff(start))
grid.segments(x0=start,x1=end, y0=0*start+0.5, y1=0*temperatures+0.5,
gp=gpar(col=rgb(res[1, ], res[2, ], res[3, ], alpha=1), lwd=10,
lineend=3))
Best wishes,
baptiste
[*] from http://www.fourmilab.ch/documents/specrend/
On 14 Mar 2009, at 12:33, baptiste auguie wrote:
Hi,
For a good discussion of the link between colour and spectra I would
suggest,
http://www.fourmilab.ch/documents/specrend/
which provides an open-source C code to perform the conversion you
ask for. I asked for some advice on how to wrap a R function around
this code last week but sadly I didn't get anywhere. Do let me know
if you succeed. (alternatively, one could port the implementation in
pure R as the code is not too complicated or computationally
demanding).
Hope this helps,
baptiste
On 14 Mar 2009, at 12:09, Jinsong Zhao wrote:
Hi there,
I try to plot visible light spectrum (380nm~780nm) with color
corresponding to the specific wavelength. However, I don't find a
function that could do this.
Another question, it's possible to plot a color space chromaticity
diagram like this:
http://upload.wikimedia.org/wikipedia/commons/thumb/0/02/CIExy1931.svg/300px-CIExy1931.svg.png
Thanks in advance!
Jinsong
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
_____________________________
Baptiste Auguié
School of Physics
University of Exeter
Stocker Road,
Exeter, Devon,
EX4 4QL, UK
Phone: +44 1392 264187
http://newton.ex.ac.uk/research/emag
______________________________
_____________________________
Baptiste Auguié
School of Physics
University of Exeter
Stocker Road,
Exeter, Devon,
EX4 4QL, UK
Phone: +44 1392 264187
http://newton.ex.ac.uk/research/emag
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
