title: How to scramble specific elements within an image?
body: <p>Although I am able to successfully scramble images (using <code>JigSaw</code>, or <code>RANDBLOCK</code>), I cannot figure out how to scramble specific matrix elements (blocks) within each image. I am unable to attach images, so precisely what I require is shown in image form <a href="http://faceresearch.org/demos/scramble" rel="nofollow">here</a> (just hit 'scramble'). As you will see, the first image is divided into an <code>8 x 7</code> matrix, and then specific elements are scrambled to produce the second image, i.e.</p>
  
  <pre><code>[1,1;1,2;1,3;1,4;1,5;2,1;2,2;2,3;2,4;2,5;3,1;3,2;3,3;3,4;3,5;4,2;4,3;4,4;5,2;5,3;5,4;6,2;6,3;6,4] 
  </code></pre>
  
  <p>I would be ever so grateful for any advice, as I am a novice to MATLAB, and need to complete the stimuli asap!  </p>
  
  <p>Many thanks in advance,</p>
  
  <p>Maria</p>