[R] measuring distances between colours?

[Ken Knoblauch]

I'd have to look it up and I'm not home at the moment. Can see later on. I would have thought that it would be normalized to have a jnd equal to 1 but I'm not sure. 

Ken

Sent from my iPhone

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Ken Knoblauch
Inserm U846
Stem-Cell and Brain Research Institute
18 av du Doyen Lépine
69500 Bron France
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On 1 juin 2013, at 18:44, "John Fox" <jfox at mcmaster.ca> wrote:

> Hi Ken,
> 
> I just tried that, and with a distance of 15 as the criterion, which seemed to work well for Lav distances, I get fewer matches for the following example that we've been using:
> 
>> cols <- c("#010101", "#EEEEEE", "#AA0000", "#00AA00", "#0000AA", "#AAAA00", "#AA00AA", "#00AAAA")
>> (nms <- rgb2col(cols, near=15))
> [1] "black"         "gray93"        "firebrick"     "#00AA00"      
> [5] "#0000AA"       "#AAAA00"       "#AA00AA"       "lightseagreen"
> 
> Do you know what a JND is supposed to be on the Luv distance scale? The Wikipedia article on CIELUV colours doesn't say.
> 
> Best,
> John
> 
>> -----Original Message-----
>> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
>> project.org] On Behalf Of Ken Knoblauch
>> Sent: Saturday, June 01, 2013 12:18 PM
>> To: John Fox
>> Cc: <r-help at r-project.org>; Michael Friendly; Martin Maechler
>> Subject: Re: [R] measuring distances between colours?
>> 
>> Hi John,
>> 
>> Out of curiosity and if it is not much trouble, I would be curious if
>> Luv worked any better than Lab. I think that Luv is supposed to be
>> preferred for monitors and Lab for surfaces but they are generally
>> pretty similar.
>> 
>> Best,
>> 
>> Ken
>> 
>> Sent from my iPhone
>> 
>> ___