Reshape array for 256 by 256 matrix showing 16 by 256

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I have 65536 real data points saved from an image. I have used reshape command to make square matrix. But result I am getting is 16 by 256 . Why is it so? Can I reconstruct the image ??
This is the .txt file and code i used is
a = load('fname.txt');
y=reshape (a,256,256)
but instead of 256 by 256 it is showing 16 by 256
George Papas
George Papas on 28 Jun 2013
Hi Sudipta! Have you tried to use the command double before resizing? As far as I understood you would like to resize your image.
1) So, from the beginning, first you can get the file:
2) Then it is very important to read and double it:
3) At the end you can resize it:
I think the most important thing is to double the image before any further post-processing step.
I hope that helps,

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Accepted Answer

Ahmed A. Selman
Ahmed A. Selman on 28 Jun 2013
Dear sudipta,
I have downloaded your data file, and went like
y=reshape (a,256,256);
Name Size Bytes Class Attributes
a 65536x1 524288 double
y 256x256 524288 double
and everything is just fine to me. So, the only possible error is that: you have another file with a name (fname.txt) in your directory which is not the same file you uploaded (1372387722318.txt). Check this out and I'm pretty sure you'll have it working.

More Answers (3)

Jan on 28 Jun 2013
Edited: Jan on 28 Jun 2013
It is impossible that Matlab's reshape changes the number of elements of the processed array. Therefore I'm convinced, that something completely different went wrong:
  1. You do not read the file your assume to read
  2. "It is showing 16 by 256" does not explain, how you check the size. Perhaps the bug is found in your method to obtain the array size.
  3. You do not use Matlab's reshape but a user-defined function. Check this by:
which reshape -all

Anand on 27 Jun 2013
This is what you should do for an image with 65536 pixels that you want to make square:
nelem = numel(A);
side = sqrt(nelem);
Areshaped = reshape(A,side,side);
  1 Comment
sudipta on 28 Jun 2013
GIvimg same result. I have upodated my question with the data and code

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David Sanchez
David Sanchez on 28 Jun 2013
To reshape/resize an image, use:
help imresize
doc imresize
for all the information needed to handle the issue.

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