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Re: Miscellaneous questions

• To: mathgroup at smc.vnet.net
• Subject: [mg36822] Re: Miscellaneous questions
• From: "Steve Gray" <stevebg at adelphia.net>
• Date: Fri, 27 Sep 2002 04:15:26 -0400 (EDT)
• References: <amrjfe$5av$1@smc.vnet.net> <amuif5$cc3$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

"Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de> wrote in message
news:amuif5$cc3$1 at smc.vnet.net...
> Hi,

[snip]

> > 2. I'm using Raster to plot data points
> > in a 256x256 array. Two problems: First,
> > regardless of the ImageSize setting (I need the
> > display as big as possible), the individual data cells
> > when examined closely at 300% vary in size by
> > almost 2:1. This makes detailed inspection of the
> > data values difficult. Surely there is some setting
> > of something which would make each data cell an
> > exact number of screen pixels?

GRAY:
    (No answer received.) I can get around this
by making the images bigger but this is not a complete
solution.

> > Second, I'm using
> > Show[ Graphics[Raster[ rescol,
> >                           ColorFunction -> Hue]],
> >                           AspectRatio -> Automatic,
> >                           ImageSize -> 700];
> > but the Hues don't allow enough easily distinguishable
> > shades to visually recognize even 6 data values easily.
> > (I'm slightly colorblind.)
>
> The most humans can distinguish 160 gray levels
>
> >It would be nice to have black
> > and white available for two of the data values, but Hue
> > does not allow this.
>
> And something like:
>
> mycolor[i_] :=
>   Switch[Round[i],
>                   0, RGBColor[0, 0, 0],
>                   1, RGBColor[1, 0, 0],
>                   2, RGBColor[1, 1, 0],
>                   3, RGBColor[0, 1, 0],
>                   4, RGBColor[0, 1, 1],
>                   5, RGBColor[0, 0, 1],
>                   _, RGBColor[1, 1, 1]]
>
> Show[Graphics[
>     Raster[Table[Random[Integer, {0, 6}], {16}, {16}],
>       ColorFunction -> mycolor, ColorFunctionScaling -> False]]]

GRAY:
    Sounds good. I'll try it. Interesting that the help does not
contain this in a form I could easily find.


> > 3. I wanted to get this raster image into a format
> > where I could dissect it with Photoshop or equivalent.
>
> And ? what does Export[] do ? it write the expression
> in a desired format, TIFF, PNG, PPM are all lossless
> compressed bitmap formats, that Mathematica can export
> and that can be imported into PhotoShop

GRAY:
    I foolishly thought something like Export would be under
the File menu.

> > After much fooling around, I found that I can export the
> > selection as an html file, read it into Navigator, do File>
> > Edit Page, which brings up Netscape Composer, right
> > click the image which, allows saving it as a GIF, which
> > I can finally work on with a photo editor. Maybe
> > there is an easier way, or maybe this description will
> > help someone with the same need.

GRAY:
    I just found that simply Copying the image and Pasting
it into Paint Shop Pro (or no doubt lots of other bitmap
editors) works.
    For outputting a Raster noninteractively, there is Export,
but I haven't tried it yet.
    Jens, thank you for your reply.