title: ImageMagick multiple operations in single invocation
body: <p>I'm trying to get ImageMagick to perform multiple operations (in this case, crops) in a single invocation, but it doesn't seem to be possible.  For example, I can do a crop, rotate, and then another crop as two separate commands:</p>
  
  <pre><code>$ convert test.jpg -crop 223x187+588+757 -rotate 330 crop2.jpg 
  $ convert crop2.jpg -crop 200x100+43+87 crop3.jpg
  </code></pre>
  
  <p>But if I try to combine them into a single command, I get an error:</p>
  
  <blockquote>
    <p>$ convert test.jpg -crop 223x187+588+757 -rotate 330 -crop
    200x100+43+87 crop3.jpg
        convert: geometry does not contain image `test.jpg' @ warning/transform.c/CropImage/666.</p>
  </blockquote>
  
  <p>Obviously I could just create a pipe, but if possible I want to avoid the extra overhead of multiple processes. Is there a way to do this?</p>
  
  <p>Update:
  Also, a pipe seems problematic: I don't want an extra compress/decompress stage so I try piping it as RGB, but I can't seem to get the parameters right:</p>
  
  <pre><code>convert test.jpg -crop 223x187+588+757 -rotate 330 rgb:- | convert -size 287x273 -depth 8 rgb:- -crop 200x100+43+87 crop3.jpg
  convert: unexpected end-of-file `-': No such file or directory @ error/rgb.c/ReadRGBImage/231.
  </code></pre>
  
  <p>Ok, so it turns out the above error is because my calculated size for the image differs from ImageMagick's calculations by two pixels.  So obviously having to try to get the image size calculation exactly the same as IM is an extra problem introduced by the need to pipeline the two commands.</p>