Has anyone plotted or is it possible to plot CIE *xy* chromaticity diagram http://en.wikipedia.org/wiki/File:CIE1931xy_blank.svg I need this plot in color. ishida [[alternative HTML version deleted]]
As it turns out, I am working on this right now, and it's a bit of a challenge to get the color gradient correct. I don't think this is really the right kind of question for this list, so let's see if anyone has attempted it or has ideas, and then take the conversation private. I can send you my not quite perfect attempt a little later today. Bryan **************** Prof. Bryan Hanson Dept of Chemistry & Biochemistry DePauw University Greencastle IN 46135 USA academic.depauw.edu/~hanson/deadpezsociety.html github.com/bryanhanson academic.depauw.edu/~hanson/UMP/Index.html On Mar 18, 2013, at 6:12 AM, ishi soichi <soichi777 at gmail.com> wrote:> Has anyone plotted or is it possible to plot > > CIE *xy* chromaticity diagram > > http://en.wikipedia.org/wiki/File:CIE1931xy_blank.svg > > > I need this plot in color. > > ishida > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at r-project.org mailing list > 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.
ishi soichi <soichi777 <at> gmail.com> writes:> Has anyone plotted or is it possible to plot > > CIE *xy* chromaticity diagram > > http://en.wikipedia.org/wiki/File:CIE1931xy_blank.svg > > I need this plot in color. > > ishida >I think that plotting the spectral locus and the line of purples is trivial, but that's not actually what you are asking. Though filling in the interior with a color gradient would be a challenging and interesting problem, there are those who would consider this a misguided attempt at representation (even though it is frequently done) as the CIE coordinates provide no information on color appearance, per se. They specify what lights look alike, not what they look like. -- 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
ishi soichi <soichi777 <at> gmail.com> writes:> Has anyone plotted or is it possible to plot > > CIE *xy* chromaticity diagram > > http://en.wikipedia.org/wiki/File:CIE1931xy_blank.svg > > I need this plot in color. > > ishida<sermon> And following up on my previous mail (diatribe), after having contemplated the image at the link that you provide, there is another significant distortion to take into account in the representation that you propose. Suppose that you are considering the appearance of isolated, centrally viewed lights in isolation, in neutral adaptation by an observer whose vision corresponds to the average observer of CIE1931. Then, the set of primaries that you will be using to generate those colors (on a screen or on paper) will have a gamut that excludes a significant portion of the diagram, so that if you take this limited gamut and stretch it out to fill the diagram, then the coordinates of the colors indicated will deviate significantly from the positions in which they are represented (not to even speak of their appearance). So, in general, while this leads to a pretty diagram, there is a lot of potential for misunderstanding in such a (mis)representation. </sermon> -- 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
I am, unfortunately, well-aware of the limitations that Ken points out (and I do appreciate him making these points). One can readily demonstrate the gamut limitations by printing the diagram Ishida links to on different devices. My hope is to get something close and include a disclaimer. Bryan On Mar 18, 2013, at 7:08 AM, Ken Knoblauch <ken.knoblauch at inserm.fr> wrote:> ishi soichi <soichi777 <at> gmail.com> writes: > >> Has anyone plotted or is it possible to plot >> >> CIE *xy* chromaticity diagram >> >> http://en.wikipedia.org/wiki/File:CIE1931xy_blank.svg >> >> I need this plot in color. >> >> ishida > > <sermon> > And following up on my previous mail (diatribe), after > having contemplated the image at the link that you > provide, there is another significant distortion to take > into account in the representation that you propose. > Suppose that you are considering the appearance of > isolated, centrally viewed lights in isolation, in neutral > adaptation by an observer whose vision corresponds to > the average observer of CIE1931. Then, the set of primaries > that you will be using to generate those colors (on a screen > or on paper) will have a gamut that excludes a significant > portion of the diagram, so that if you take this limited gamut > and stretch it out to fill the diagram, then the coordinates of > the colors indicated will deviate significantly from the positions > in which they are represented (not to even speak of their > appearance). So, in general, while this leads to a pretty > diagram, there is a lot of potential for misunderstanding > in such a (mis)representation. </sermon> > > -- > 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 > > ______________________________________________ > R-help at r-project.org mailing list > 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.