title: 2D discrete cosine transform
body: <p>I checked with <code>dct</code> function in Matlab but it only implemented DCT along the columns for a matrix input:</p>
  
  <pre><code>&gt;&gt; help dct 
  If X is a matrix, the DCT operation is applied to each
  column.
  </code></pre>
  
  <p>Is there a function that can perform 2D DCT in Matlab, or are there some algorithms that can apply <code>dct</code>, make some transform, then obtain the 2D DCT?</p>