title: plot a log natural and get gamma of image
body: <p>link <a href="http://i.stack.imgur.com/TWzIH.jpg" rel="nofollow">b.jpg</a></p>
  
  <pre><code>i=imread('b.jpg');
  i1=rgb2gray(i);
  i2=im2double(i);
  j=log(1+i2);
  </code></pre>
  
  <p>1.</p>
  
  <p>now this for get histograme of image.</p>
  
  <pre><code> imhist(j);
  </code></pre>
  
  <p>say error:</p>
  
  <pre><code>??? Error using ==&gt; iptcheckinput
  Function IMHIST expected its first input, I or X, to be two-dimensional.
  
  Error in ==&gt; imhist&gt;parse_inputs at 270
  iptcheckinput(a, {'double','uint8','logical','uint16','int16','single'}, ...
  
  Error in ==&gt; imhist at 57
  [a, n, isScaled, top, map] = parse_inputs(varargin{:});
  </code></pre>
  
  <p>=============================================================================</p>
  
  <p>2.how can draw diagrame of function?</p>
  
  <pre><code>     plot(j,i2);
  
  ??? Error using ==&gt; plot
  Data may not have more than 2 dimensions
  </code></pre>
  
  <p>==============================================================================
  3.how can get gamma of <code>j</code></p>