On Mon, 7 Jul 2008, hadley wickham wrote:
If you replace this by
hcl$colour <- hcl(hcl$h, hcl$c, hcl$l, fixup = FALSE)
with(hcl, plot(x, y, col=colour, pch=20))
Then, the resulting "wheel" has three overlapping "holes" corresponding to
the colors previously fixed.
Oops, thanks for pointing that out.
Also, as hue/chroma correspond to polar coordinates in the UV plane of
CIELUV, it makes more sense to plot wheels in the hue/chroma plane for fixed
luminance. To draw a hue/luminance plane for fixed chroma is harder to
interpret geometrically.
Oooh, I guess if I'd thought about that for a couple of seconds I
would have a realised that! What are good values to use for luminance
and chroma in that case?
There are some utility visualization functions in the devel-version of
"colorspace" on R-Forge. Try:
source(url("http://r-forge.r-project.org/plugins/scmsvn/viewcvs.php/*checkout*/pkg/paper/Colorspace/visualizations.R?rev=13&root=colorspace";))
hue_chroma_plane()
chroma_luminance_plane()
I can't seem to find a slice which gives me
a decently wheel-like slice? Or should I just use fixup = TRUE, or
accept that true colour wheels displayed on rgb monitors don't look
like wheels?
They always look a bit awkward, more like rectangles or triangles, but you
could limit the maximum chroma, then it looks a bit more like a wheel.
hue_chroma_plane(c = 0:50)
But you can never get the full wheel if you want to balance with respect
to luminance. Or conversely, if you construct a wheel like
hue_saturation_plane()
then it is not balanced with respect to lumincance.
Z
Hadley
--
http://had.co.nz/
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