Max Kuhn <mxkuhn <at> gmail.com> writes: > > Yes, I was aware of the different type and their respective prevalences. > > The dichromat package helped me find what I needed. > > Thanks, > > Max > > On Wed, Nov 2, 2011 at 6:38 PM, Thomas Lumley <tlumley <at> uw.edu> wrote: > > On Thu, Nov 3, 2011 at 11:04 AM, Carl Witthoft <carl <at> witthoft.com> wrote: > >> > >> Before you pick out a palette: you are aware that their are several > >> different types of color-blindness, aren't you? > > > > Yes, but to first approximation there are only two, and they have > > broadly similar, though not identical impact on choice of color > > palettes. The dichromat package knows about them, and so does > > Professor Brewer. > > > > More people will be unable to read your graphs due to some kind of > > gross visual impairment (cataracts, uncorrected focusing problems, > > macular degeneration, etc) than will have tritanopia or monochromacy. > > > > -thomas > >
Sorry to come into this late, but I was travelling. As indicated, the dichromat package will give you an excellent first order approximation as to what works or doesn't for the 3 types of congenital dichromacies, As indicated by THomas, the two most prevalent varieties, protanopia and deuteranopia, result in similar confusion axes and the third, tritanopia, is relatively rare, except in eye disease. That said, the most prevalent color deficiencies are not the dichromacies but the anomalous trichromacies. These will not necessarily lead to losses in chromatic discrimination but just shifts (i.e., one might see as orange or green what a normal trichromat sees as yellow). About 20 years ago, I was involved in an attempt to develop guidelines (or rules of thumb, at least) for display design for color deficient observers, that did not require any deep understanding of colorimetry. The distillation of this effort can be found here, for what it is worth;: http://www.lighthouse.org/accessibility/design/ accessible-print-design/effective-color-contrast The most important point, I think, was to make sure that there was a sufficient luminance contrast difference, so that in the absence of the capacity to make a chromatic discrimination, the differences would still be detectable. The principles necessary for optimizing color choices in a scatterplot will certainly be more complex, however. In this light (no pun intended), I would draw your attention to the seminal work of Berniece Rogowitz at IBM: http://www.research.ibm.com/people/l/lloydt/ color/color.HTM http://www.research.ibm.com/dx/proceedings/ pravda/truevis.htm who was (is) quite concerned with this issue, as well, as the excellent article by Zeileis, Hornik and Murrell http://statmath.wu.ac.at/~zeileis/papers/ Zeileis+Hornik+Murrell-2009.pdf HTH, Ken -- Ken Knoblauch Inserm U846 Stem-cell and Brain Research Institute Department of Integrative Neurosciences 18 avenue du Doyen Lépine 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 ______________________________________________ [email protected] 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.
