title: How to save single channel EXR images with ImageMagick
body: <p>I have a 32 bit single channel EXR image that I want to crop using ImageMagick, the problem is after I crop it it got saved into 32 bit 3 channel image by ImageMagick.</p>
  
  <p>Below are the attempts that I tried that didn't work</p>
  
  <pre><code>mogrify -crop 200x100+238+200 test.exr -colorspace Y
  </code></pre>
  
  <p>This returns error mogrify: unrecognized image colorspace `Y'.</p>
  
  <pre><code>mogrify -crop 200x100+238+200 test.exr -channel Y
  </code></pre>
  
  <p>This returns 32 bit 3 channel image.</p>
  
  <pre><code>mogrify -crop 200x100+238+200 test.exr -separate 
  </code></pre>
  
  <p>This returns 8 bit 1 channel image.</p>
  
  <p>I am on Ubuntu 16.04 and my version of ImageMagick is 6.9.6-4 Q32 x86_64.</p>
  
  <p>How can I make ImageMagick to save my EXR file with the original single channel 32 bit format?</p>