R-beta: graphics: ``gamma correction'' -- state / feedback ?
Martin Maechler
maechler at stat.math.ethz.ch
Thu Nov 6 20:08:01 CET 1997
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/
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