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Atte Tenkanen

2015-Jul-25 19:49 UTC

[R] Opposite color in R

Hi,

I have tried to find a way to find opposite or complementary colors in R.

I would like to form a color circle with R like this one: 
http://nobetty.net/dandls/colorwheel/complementary_colors.jpg

If you just make a basic color wheel in R, the colors do not form 
complementary color circle:

palette(rainbow(24))
Colors=palette()
pie(rep(1, 24), col = Colors)

There is a package ?colortools? where you can find function opposite(), 
but it doesn?t work as is said. I tried

library(colortools)
opposite("violet") and got green instead of yellow and

opposite("blue") and got yellow instead of orange.

Do you know any solutions?

Atte Tenkanen

peter dalgaard

2015-Jul-26 00:04 UTC

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[R] Opposite color in R

> On 25 Jul 2015, at 21:49 , Atte Tenkanen <attenka at utu.fi> wrote:
> 
> Hi,
> 
> I have tried to find a way to find opposite or complementary colors in R.
> 
> I would like to form a color circle with R like this one:
http://nobetty.net/dandls/colorwheel/complementary_colors.jpg
> 
> If you just make a basic color wheel in R, the colors do not form
complementary color circle:
> 
> palette(rainbow(24))
> Colors=palette()
> pie(rep(1, 24), col = Colors)
> 
> There is a package ?colortools? where you can find function opposite(), but
it doesn?t work as is said. I tried
> 
> library(colortools)
> opposite("violet") and got green instead of yellow and
> 
> opposite("blue") and got yellow instead of orange.
> 
> Do you know any solutions?
Not directly, but a few hints: 

First read up on "complementary colors" in Wikipedia. In particular,
note that the traditional color circle does not satisfy the modern definition of
opposite-ness. E.g. red paint mixed with green paint is brown, not black or
grey.

The construction of the color circle is simple in principle: red, blue, yellow
go at 0, 120, 240 degrees, the other colors on the circle are formed by mixing
two primaries in varying proportions: green (at 180 deg) is an equal mixture of
blue and yellow, violet (at 60 deg) of blue and red, orange (at 300 deg) of red
and yellow. Blue-green (at 150 deg) would be half blue, half green, alias three
quarter blue, one quarter yellow. Etc.

The tricky bit is that the above mixtures are subtractive mixtures (mixing paint
rather than light beams) and I don't know how to make a subtractive color
mixture in the additive RGB space that we usually work in. Maybe there are tools
in the colortools package?

-pd
> 
> Atte Tenkanen
> 
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com

ken knoblauch

2015-Jul-26 06:45 UTC

head link

[R] Opposite color in R

peter dalgaard <pdalgd <at> gmail.com> writes:
> 
> 
> > On 25 Jul 2015, at 21:49 , Atte Tenkanen 
<attenka <at> utu.fi> wrote:> > 
> > Hi,
> > 
> > I have tried to find a way to find opposite 
or complementary colors in R.> > 
> > I would like to form a color circle with R like this one: http://nobetty.net/dandls/
colorwheel/complementary_colors.jpg> > 
> > If you just make a basic color wheel in R, 
the colors do not form complementary color circle:> > 
> > palette(rainbow(24))
> > Colors=palette()
> > pie(rep(1, 24), col = Colors)
> > 
> > There is a package ?colortools? where you can find function opposite(), but it doesn?t work as
is> said. I tried
> > 
> > library(colortools)
> > opposite("violet") and got green instead of yellow and
> > 
> > opposite("blue") and got yellow instead of orange.
> > 
> > Do you know any solutions?
> 
> Not directly, but a few hints: 
> 
> First read up on "complementary colors" in Wikipedia. In particular, note that the traditional
color> circle does not satisfy the modern definition of opposite-ness. E.g. red paint mixed with green paint
is> brown, not black or grey.
> 
> The construction of the color circle is simple in principle: red, blue, yellow go at 0, 120, 240 degrees,
the> other colors on the circle are formed by mixing two primaries in varying proportions: green (at 180 deg)
is> an equal mixture of blue and yellow, violet (at 60 deg) of blue and red, orange (at 300 deg) 
of red and yellow.> Blue-green (at 150 deg) would be half blue, half green, alias three quarter blue, one quarter
 yellow. Etc.> 
> The tricky bit is that the above mixtures are subtractive mixtures (mixing paint rather than light
beams)> and I don't know how to make a subtractive color mixture in the additive RGB space 
that we usually work in.> Maybe there are tools in the colortools package?
> 
> -pd
> 
> > 
> > Atte Tenkanen
To start with, you should be specifying your "colors"
or lights actually in an additive color space like
CIE 1931 xy,
https://en.wikipedia.org/wiki/CIE_1931_color_space
which you can do in the colorspace package.
But this is based on an average observer and
the results are unlikely to match a given 
individual's vision.  On top of that, decisions made
when this norm was specified are such that it
deviates from human vision for short wavelengths
so that you would be better off using a corrected
version like that proposed by Judd in the 1950's
or for the most recent suggestion see
ww.cvrl.org
under 
New CIE XYZ functions transformed 
from the CIE (2006) LMS functions

best, 

Ken

-- 
Kenneth Knoblauch
Inserm U846
Stem-cell and Brain Research Institute
Department of Integrative Neurosciences
18 avenue du Doyen L?pine
69500 Bron
France
tel: +33 (0)4 72 91 34 77
fax: +33 (0)4 72 91 34 61
portable: +33 (0)6 84 10 64 10
http://www.sbri.fr/members/kenneth-knoblauch.html

Franklin Bretschneider

2015-Jul-26 15:53 UTC

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[R] Opposite color in R

Dear Atte Tenkanen,


Re:> Hi,
> 
> I have tried to find a way to find opposite or complementary colors in R.
> 
> I would like to form a color circle with R like this one:
http://nobetty.net/dandls/colorwheel/complementary_colors.jpg
> 
> If you just make a basic color wheel in R, the colors do not form
complementary color circle:
> 
> palette(rainbow(24))
> Colors=palette()
> pie(rep(1, 24), col = Colors)
> 
> There is a package ?colortools? where you can find function opposite(), but
it doesn?t work as is said. I tried
> 
> library(colortools)
> opposite("violet") and got green instead of yellow and
> 
> opposite("blue") and got yellow instead of orange.
> 
> Do you know any solutions?
> 
> Atte Tenkanen

Actually, yellow and blue are complementary colours, but red and green
aren't.

The human visual system has three types of cones: red-sensitive, green-sensitive
and blue-sensitive.
(the labels are approximate, e.g. red-sensitive cones have their optimum
sensitivity at a wavelength we might call orange, but for understanding colours,
R-G-B is the useful standard designation).
A certain combination of these three together, such as in sunlight, is seen as
white. In the digital domain, the three "colour channels" of an image
are usually scaled to 8-bit numbers, i.e. from zero up to and including 255. So,
all three channels 255 makes white.

Leaving one of the three colors out yields yellow (no blue), magenta (no green)
and cyan (no red). The pairs yellow-blue, magenta-green and cyan-red  are truly
complementary colours.

Colours are the result of the wavelength of the light, so one would expect
colours to lie on a linear scale, from about 700 nm (red), through 550 (green)
to about 440 nm (blue).

There is a complication, however: the photosensitive pigment of our red cones
has a second action peak past that of the blue cones, so past pure blue we see a
sort of reddish blue, in other words violet or purple. Therefore, the colours
can be plotted in a circle, where violet and purple fill the gap between blue
and red.

Using a combination of the three ground colors R, G and B, any desired colour
shade can be composed. Orange, for example, consists of (approximately) all red
and half green.

- - - - - - - - -

R has ample possibilities to compose colours or colour palettes, with which one
can create (almost continuous) gradients or stepwise colour patches.
Examples are col2rgb():
>col2rgb("orange")      [,1]
red    255
green  165
blue     0
>col2rgb("violet")      [,1]
red    238
green  130
blue   238

Cindy Brewer wrote a fine set of colour functions, adapted to R by Erich
Neuwirth. See package "RColorBrewer".

And much can be done with the standard R distribution:
 
The following code plots a some colours in a circle, with the complementary
colours at opposite sides (so crudely what you're after):


# define colour triplets
reds =   c( 255, 255,  255,    0,    0,    0,    0,  128)
greens = c(   0, 127,  255,  255,  255,  127,    0,    0)
blues=   c(   0,   0,    0,    0,  255,  255,  255,  255)
n = length(reds)
#  compute circle to plot in
stp = 2*pi/n
th = seq(0,2*pi-stp, length.out=n)
x = cos(th); y=sin(th)
#  plot (on a Mac, for other OSses call the appropriate grahics window
quartz(w=5, h=5)
par(xpd=NA)
plot(x,y,pch=15, cex=8, col=rgb(reds, greens, blues, maxColorValue = 255),
asp=1, axes=FALSE, xlab='', ylab='')
points(x,y,pch=0, cex=8, col="black")
# arrows connect the complementary colours
arrows(0,0, 0.7*x, 0.7*y, length = 0.25, col = "grey")

Hope this helps;
Best wishes,


Frank
------

Franklin Bretschneider
Dept of Biology
Utrecht University
bretschr at xs4all.nl

Steve Taylor

2015-Jul-27 23:23 UTC

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[R] Opposite color in R

I wonder if the hcl colour space is useful?  Varying hue while keeping chroma
and luminosity constant should give varying colours of perceptually the same
"colourness" and brightness.

?hcl
pie(rep(1,12),col=hcl((1:12)*30,c=70),border=NA)


-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Atte Tenkanen
Sent: Sunday, 26 July 2015 7:50a
To: r-help at r-project.org
Subject: [R] Opposite color in R

Hi,

I have tried to find a way to find opposite or complementary colors in R.

I would like to form a color circle with R like this one: 
http://nobetty.net/dandls/colorwheel/complementary_colors.jpg

If you just make a basic color wheel in R, the colors do not form 
complementary color circle:

palette(rainbow(24))
Colors=palette()
pie(rep(1, 24), col = Colors)

There is a package ?colortools? where you can find function opposite(), 
but it doesn?t work as is said. I tried

library(colortools)
opposite("violet") and got green instead of yellow and

opposite("blue") and got yellow instead of orange.

Do you know any solutions?

Atte Tenkanen

______________________________________________
R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.

R help - Jul 2015 - Opposite color in R

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