As a follow-up to this issue:
A revised version of the "colorspace" package is now available on R-Forge
at https://R-Forge.R-project.org/R/?group_id=20
This provides a function whitepoint() that can query and/or modify the
whitepoint used in all color conversions within the package. To try it you
can do:
install.packages("colorspace", repos="http://R-Forge.R-project.org";)
example("whitepoint", package = "colorspace")
Glenn, it would be great if you could try this and let us know if any
problems remain.
On Mon, 4 Jun 2018, Achim Zeileis wrote:
Glenn,
currently, this is currently not exposed in "colorspace" AFAICS. You can
modify it by changing .WhitePoint inside colorspace's NAMESPACE, though:
R> assignInNamespace(".WhitePoint", rbind(c(95, 100, 105)),
+ ns = "colorspace")
R> as(XYZ(100, 100, 100), "LAB")
L A B
[1,] 100 8.622384 3.226371
I'll have another look whether this could be exposed easily (cc also Paul).
Best,
Z
On Mon, 4 Jun 2018, Glenn Davis wrote:
In colorspace.R I see:
setAs("color", "LAB", function(from)
LAB(.Call("as_LAB", from@coords, class(from), .WhitePoint, PACKAGE = "
colorspace"),
names = dimnames(from@coords)[[1]]))
...
.WhitePoint = NULL
and then in colorspace.c and the function CheckWhite(),
I see that .WhitePoint = NULL is converted to D65.
I would like to pass a different .WhitePoint to
as( XYZ( 100,100,100) , "LAB" )
I have tried 3 methods:
as( XYZ( 100,100,100) , "LAB", .WhitePoint=XYZ(95,100,105) )
.WhitePoint = XYZ(95,100,105)
assign( ".WhitePoint", XYZ(95,100,105), env=as.environment('package:
colorspace') )
but all fail, for different reasons.
How can I transform XYZ to LAB using a whitepoint different than D65 ?
Thanks,
Glenn Davis
gda...@gluonics.com
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