Re: Showing a limited GrayLevel
- To: mathgroup at smc.vnet.net
- Subject: [mg19074] Re: Showing a limited GrayLevel
- From: "Atul Sharma" <atulksharma at yahoo.com>
- Date: Thu, 5 Aug 1999 01:34:59 -0400
- References: <7o5eg9$rf1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
In general, function values are scaled to the range 0-1 and then assigned a
color function based on this scaled value. This particular issue is even
more relevant if you use ColorFunction -> Hue, since the latter assigns the
red color to both a 0 and 1, making for very confusing images. The solution
in both cases is to apply an anonymous function which scales the 0-1 value
generated automatically to only part of the range. The following function
illustrates how this works if you want to drop the range 0-0.5 in the
GrayLevel assignment. The same construct works for Hue, incidentally.
ContourPlot[Sin[x] Sin[y], {x, -2, 2}, {y, -2,
2},ColorFunction->(GrayLevel[1-#/2] &)]
Atul Sharma
PS: This is well described in Mathematica in Action, Second Edition
Stan Wagon (TELOS/Springer-Verlag, 1999), which includes the following
example using RGB Color to code the output in tones ranging from blue to
pink by varying the amount of red in the mix.
ColorFunction->(RGBColor[0.3+ 0.7 #, 0.4, 0.8]&)]
Steve Hocter wrote in message <7o5eg9$rf1 at smc.vnet.net>...
> I have a quick question about changing the GrayLevel in contour plots.
>
> When using ContourPlot, how is it possible to limit the GrayLevel range?
>That is, instead of GrayLevel being scaled between 0 and 1, the contours
>would be shown between 0.5 and 1 cutting out any totally black parts of the
>plot.
>
> Thanks,
>
> Steve.
>
>--
> -----------------------------------------------------------------
> | Steven T. Hocter Dept Of Maths |
> | mad00 at keele.ac.uk Keele University |
> | steve at weinstein.maths.keele.ac.uk |
> -----------------------------------------------------------------
>