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MathGroup Archive 2005

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Re: Beginner : how to convert .bmp or .jpeg for digital processing

  • To: mathgroup at smc.vnet.net
  • Subject: [mg57155] Re: Beginner : how to convert .bmp or .jpeg for digital processing
  • From: "Peltio" <peltio at trilight.zone>
  • Date: Thu, 19 May 2005 03:08:31 -0400 (EDT)
  • References: <d6bi9d$moh$1@smc.vnet.net>
  • Reply-to: "Peltio" <peltioNOSPAM at despammed.com.invalid>
  • Sender: owner-wri-mathgroup at wolfram.com

"Peter van Daalen" wrote

>Being a Mathematica beginner, I failed in finding the way to convert
>..jpeg and .bmp formats into 2D and 3D numerical ( 0-255) arrays.

Don't know for 3D pictures, but as long as you stick with 2D ones (and you
have access to a version of Mathematica with Import) this should do what you want:

    pic=Import["JohnDoesSkull.jpg"];

This is the array you were looking for:
    vals=pic[[1,1]];
    Dimensions[vals]

This shows the array by rescaling the values:

    Show[Graphics[Raster[vals/Max[vals]]], AspectRatio -> Automatic]

This is an enhanced negative image

    Show[Graphics[Raster[1 - vals^2/Max[vals^2]]], AspectRatio -> Automatic]

cheers,
Peltio
I hope you have plenty of RAM, since I've a hunch that an hires x-rays image
can be quite huge.



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