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Re: Invert Black/White Colors of Binary Images

  • To: mathgroup at smc.vnet.net
  • Subject: [mg84173] Re: Invert Black/White Colors of Binary Images
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Wed, 12 Dec 2007 19:56:56 -0500 (EST)
  • Organization: Uni Leipzig
  • References: <fjnupg$fhc$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de

Hi,

RandomBinaryImage[white_?NumericQ, nx_Integer, ny_Integer] :=
  Module[{dta},
   dta = Table[If[Random[] < white, 1, 0], {nx*ny}];
   Graphics[
    Raster[Partition[dta, nx], {{0, 0}, {nx, ny}}, {0, 1},
     ColorFunction -> GrayLevel]
    ]
   ]

should create a random binary image of size nx*ny with
0<=white<=1 white pixels. So

RandomBinaryImage[0.05, 256, 256]

will generate approx 5% white pixels and

RandomBinaryImage[0.95, 256, 256]

95 % white pixels.

Regards
   Jens

Tara.Ann.Lorenz at gmail.com wrote:
> Hi,
> 
> I am using the following code to create black and white images with
> 5%  black pixels and 95% white pixels:
> 
> blackcolor = Table[1, {45}];
> whitecolor = Table[0, {855}];
> arrayvalues = Join[blackcolor, whitecolor];
> randompermutation := RandomSample[Range[1, 900]];
> image := Partition[arrayvalues[[randompermutation]], 30];
> t1 = Graphics[Raster[image]]
> 
> How can I invert the coloring to have 5% white and 95% black??
> 
> Thank you,
> Tara
> 


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