title: How to make convolution with maxout activation?
body: <p>I want my activation function select maximal value, generated by <code>N</code> filters of <code>M x M</code> convolution. This layer would convert <code>X</code> channel image to 1-channel one.</p>
  
  <p>How to do that?</p>
  
  <p>First I wrote</p>
  
  <pre><code>classifier.add(Conv2D(3, (5, 5), activation='linear')
  classifier.add(MaxPooling2D(pool_size=1, strides=1))
  </code></pre>
  
  <p>but then thought it doesn't return 1-channel image, but returns 3 channel.</p>
  
  <p>How to do the job?</p>