[R] package colorspace and .WhitePoint question

[Achim Zeileis]

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 using coords, class(from), .WhitePoint, PACKAGE = "
> colorspace"),
>          names = dimnames(from using 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
> gdavis using gluonics.com
>
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