Martin Maechler
1997-Nov-06 19:08 UTC
R-beta: graphics: ``gamma correction'' -- state / feedback ?
In 'CHANGES' of 0.49, you find among "NEW FEATURES" o There is a new graphical parameter "gamma" which is designed to let users apply a ``gamma'' correction for their graphics displays. Most monitors produce a color intensity which is related to voltage by the equation intensity = voltage ^ gamma with gamma about 2.5 for most PC monitors. A typical symptom of this non-linearity is that a colorwheel produced by piechart(rep(1,48), col=48) shows a marked over representation of the red, green and blue and blue primaries. If this is the case try par(gamma=1/2.5) and redraw the color wheel. Vary gamma till you have a "nice" spectrum. This is experimental and feedback would be welcome. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (If this is useful we will do the same for postscript). ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (underlines "~~" by me). - What is the state of this? - Is it still experimental? - Does it also work in postscript? - Who of you R users has used it? successfully? - if yes, can you dig out a nice example of its use? The main reason for my questions is that I am updating the online documentation, and I'd like to write something in (at least) ?hsv and ?par Thank you for your feedback! {{If you are not one of R&R, you also may e-mail to me alone, and I'll summarize to the list ..}} ---- Martin Maechler <maechler at stat.math.ethz.ch> <>< Seminar fuer Statistik, SOL G1 ETH (Federal Inst. Technology) 8092 Zurich SWITZERLAND phone: x-41-1-632-3408 fax: ...-1086 http://www.stat.math.ethz.ch/~maechler/ =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=