Prev: Extract the portion from image
Next: Abort problem on Mac (Matlab 2009b, 64 bit edition)
From: astro mmi on 12 Feb 2010 15:42
Hi everyone,
Is there ant command in MATLAB to select a matrix of pixels from a whole image. For example, i want only the first 3*3 pixels, then the next 3*3 and so on. Is there a way I can do it?
Thanx in advance.
From: ImageAnalyst on 12 Feb 2010 15:45
Just use regular indexing:

m = magic(8) % Generate some sample data
m3by3 = m(1:3,1:3) % Get the upper left 3x3 portion
From: astro mmi on 12 Feb 2010 15:59
Thank you so much.
I have another query as to how I can find the center of this matix using a MATLAB command.Thanx


ImageAnalyst <imageanalyst(a)mailinator.com> wrote in message <0beca35d-9a71-403b-8c94-fc90604e289a(a)o26g2000vbd.googlegroups.com>...
> Just use regular indexing:
>
> m = magic(8) % Generate some sample data
> m3by3 = m(1:3,1:3) % Get the upper left 3x3 portion
From: Walter Roberson on 12 Feb 2010 16:32
astro mmi wrote:
> Hi everyone,
> Is there ant command in MATLAB to select a matrix of pixels from a
> whole image. For example, i want only the first 3*3 pixels, then the
> next 3*3 and so on. Is there a way I can do it?

Perhaps you want blkproc(). Note, though, that blkproc() can process the
blocks in any order, so if you need to have them processed in a specific order
or if you need to know the coordinates of the block you are processing, then
you will need to program your own version.
From: Nathan on 12 Feb 2010 16:53
On Feb 12, 12:59 pm, "astro mmi" <pyarsa_ma...(a)yahoo.co.in> wrote:
> Thank you so much.
> I have another query as to how I can find the center of this matix using a MATLAB command.Thanx
>

Which matrix do you mean? The 3 by 3 matrix or the image matrix?

If it's the 3 by 3 matrix, you can just do:
centerofmatrix = m3by3(2,2);
OR (as shown below)
centerofmatrix = m3by3((size(m3by3,1)+1)/2,(size(m3by3,2)+1)/2)

If it's the image matrix the center pixel can only be found if it's an
odd x odd matrix as such:

centerofimage = matrix((size(matrix,1)+1)/2,(size(matrix,2)+1)/2)

If either of the dimensions are even, you have to decide what is
considered to be the "center".

I hope this helps.

-Nathan


 | 
Pages: 1
Prev: Extract the portion from image
Next: Abort problem on Mac (Matlab 2009b, 64 bit edition)