Histogram Equalization yielding unexpected results
<p>I have a series of images with decreasing brightness that I would like to try to correct with histogram equalization. I applied <code>histeq</code> to some test data to learn how the function works</p>

<pre><code>% Image that I would like to apply histogram equalization to
C = gallery('wilk',21);
figure, imagesc(C)

E = histeq(C);
figure, imagesc(E);
</code></pre>

<p>However, when I look at the output of <code>histeq</code>, I get a result that only has two unique values: <code>0.873</code> and <code>1.000</code>. How come the output doesn't span the whole range of the input? I would expect there to be more than two unique values in the output.</p>

<p><a href="https://i.stack.imgur.com/Ekvjw.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Ekvjw.jpg" alt="enter image description here"></a></p>