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 ___ Ken Knoblauch Inserm U846 Stem-Cell and Brain Research Institute 18 av du Doyen L?pine 69500 Bron France Tel : 04 72 91 34 77 Fax : 04 72 91 34 61 portable : 06 84 10 64 10 http://www.sbri.fr/members/kenneth-knoblauch.html
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 ___