title: In matlab, colormap has no effect on image
body: <p>I am trying to convert an image I have to have a concentration-ish look using matlab. I want it show a range of concentration values for the green part of the image, shown below:</p>
  
  <p><img src="https://i.stack.imgur.com/L1cU5.png" alt="enter image description here"></p>
  
  <p>I load in the image and try to change the color map:</p>
  
  <pre><code>&gt;&gt; ex1 = imread('C:\Users\Tyler\Documents\Dropbox\ex1.png');
  &gt;&gt; imshow(ex1)
  &gt;&gt; colormap(grey)
  </code></pre>
  
  <p>This changes what the colorbar looks like, but has absolutely no affect on the image itself. It is still green with the purple below it. Why does this not change the image, in the way that just changing the colormap in <a href="http://www.mathworks.com/help/techdoc/ref/colormap.html" rel="nofollow noreferrer">documentation</a> does.</p>
  
  <p>Tyler</p>