Re: [R] Drawing a colour wheel - bug in hcl?

From: hadley wickham <h.wickham_at_gmail.com>
Date: Mon, 07 Jul 2008 16:54:35 -0500

> 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? 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?

Hadley

-- 
http://had.co.nz/

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Received on Mon 07 Jul 2008 - 22:00:04 GMT

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