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MathGroup Archive 2006

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Re: Image Processing

  • To: mathgroup at smc.vnet.net
  • Subject: [mg66080] Re: [mg66055] Image Processing
  • From: "Carl K. Woll" <carlw at wolfram.com>
  • Date: Sat, 29 Apr 2006 03:40:09 -0400 (EDT)
  • References: <200604281032.GAA03084@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Charlie Springer wrote:
> Hi all.
> 
> Old physicist, new Mathematica user.
> 
> I want to perform 2D FFT's on images. I have used Import to get a JPEG into 
> apparently, a graphic object. I can not see how to get it into a "list of 
> lists" or any form acceptable to Fourier[].
> 
> Anybody have a snippet or some experience? I'm still learning the 
> terminology. If this works out I'll get the grid version for a Mac Quad.
> 
> -- Charlie Springer

Import of JPEG's yields graphics objects of the structure:

Graphics[ Raster[data], opts ]

If you import your jpeg using Import:

jpeg = Import["picture", "JPEG"];

Then you can extract the raster data structure using

raster = jpeg[[1]]

Look up Raster in the help browser to see how a Raster object is 
structured. Basically, the first element of the raster is your 2D array 
of cells.

Carl Woll
Wolfram Research


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