[R] Selecting complementary colours

[Michael Kubovy]

Hi All,

Complementary colors will not insure legibility. If the text and the  
background are equiluminant, visibility will be severely impaired.

On May 21, 2007, at 8:22 PM, John Fox wrote:

> Dear Achim,
>
> As I mentioned in my response to Deepayan's suggestion, I didn't  
> specify the
> original problem clearly: The object is to get contrasting colours,  
> so that
> when one is plotted over the other, the two will be readily  
> distinguishable.
> Your suggestions don't do this for neutral colours:
>
>> x <- "#888888"
>> y_hcl <- as(hex2RGB(x), "polarLUV")
>> y_hcl at coords[1, "H"] <- y_hcl at coords[1, "H"] + 180
>> hex(y_hcl)
> [1] "#888888"
>
>> y_hsv <- as(hex2RGB(x), "HSV")
>> y_hsv at coords[1, "H"] <- y_hsv at coords[1, "H"] + 180
>> hex(y_hsv)
> [1] "#888888"
>
> Thank you for trying to help.
>
> John
>
> --------------------------------
> John Fox, Professor
> Department of Sociology
> McMaster University
> Hamilton, Ontario
> Canada L8S 4M4
> 905-525-9140x23604
> http://socserv.mcmaster.ca/jfox
> --------------------------------
>
>> -----Original Message-----
>> From: Achim Zeileis [mailto:Achim.Zeileis at wu-wien.ac.at]
>> Sent: Monday, May 21, 2007 7:07 PM
>> To: John Fox
>> Cc: r-help at stat.math.ethz.ch
>> Subject: Re: [R] Selecting complementary colours
>>
>> On Mon, 21 May 2007, John Fox wrote:
>>
>>> Dear r-helpers,
>>>
>>> I wonder whether, given the "#rrggbb" representation of a colour,
>>> there is a simple way to select the complementary colour,
>> also expressed as a "#rrggbb"
>>> string.
>>
>> Is the complementary color uniquely defined? My understanding
>> is that you can take opposite colors on a color wheel, but
>> there are of course various color wheels available. With
>> "colorspace" you can experiment with this,
>> e.g.:
>>   x <- "#81A9D0"
>>   y_hcl <- as(hex2RGB(x), "polarLUV")
>>   y_hcl at coords[1, "H"] <- y_hcl at coords[1, "H"] + 180
>>   y_hcl <- hex(y_hcl)
>> which is a bit more balanced than
>>   y_hsv <- as(hex2RGB(x), "HSV")
>>   y_hsv at coords[1, "H"] <- y_hsv at coords[1, "H"] + 180
>>   y_hsv <- hex(y_hsv)
>>
>> hth,
>> Z
>>
>>
>>
>
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> PLEASE do read the posting guide http://www.R-project.org/posting- 
> guide.html
> and provide commented, minimal, self-contained, reproducible code.

_____________________________
Professor Michael Kubovy
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Department of Psychology
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