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Re: Convert Binary Image to Column Vector

  • To: mathgroup at smc.vnet.net
  • Subject: [mg83977] Re: Convert Binary Image to Column Vector
  • From: Szabolcs Horvát <szhorvat at gmail.com>
  • Date: Thu, 6 Dec 2007 02:38:31 -0500 (EST)
  • References: <fj65hr$fp1$1@smc.vnet.net>

Tara.Ann.Lorenz at gmail.com wrote:
> Can a 30x30 binary image be converted directly into a column vector of
> 900 components in Mathematica? 

It depends on what you mean by "image",

> Or must the image first be put into
> matrix form?  

and what you mean by "matrix".

> I am using the command:
>  Flatten@Transpose@t1, 

This command works if t1 is a two-dimensional array, i.e. a nested list 
that looks like this when output is set to StandardForm:

{{1,2},{3,4}}

> where t1 is my binary image, and it seems to
> give me a vector but I'm not sure if it's the one that I desire.
> 
> If I first convert my image into matrix form 

How did you do this conversion?  If the image is inside 
Graphics[Raster[...]], then you need to extract the contents of Raster[...].

> and define my matrix as
> "m" and then use this command,
> Flatten@Transpose@m, then I get an output of "Transpose[...]" and my
> 30 x 30 matrix is explicitly written within the Transpose brackets.
> This does not provide me a column vector with 900 components, which is
> what I am looking for.

In Mathematica there are no column or row vectors, only vectors and 
matrices (one might call n*1 matrices column vectors and 1*n matrices 
row vectors).  Have you read the post I suggested in my answer to you 
last question?

Here's the link again:

http://groups.google.com/group/comp.soft-sys.math.mathematica/browse_thread/thread/24fa2f19317734fa/69770c22c257ca29#69770c22c257ca29

If you use TraditionalForm output, try switching to StandardForm for a 
while to better understand how matrices/vectors are represented.

Szabolcs


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