title: CoreImage CICrop returning 0x0 pixel image
body: <p>Apologies for so many questions today, Friday dead brain symptom setting in.</p>
  
  <p>I have a CICrop filter:</p>
  
  <pre><code>[crop setValue:beginImage forKey:@"inputImage"];  //give the crop filter the beginImage
      [crop setValue:[CIVector vectorWithX:0.0f Y:0.0f Z:_exportSize W:_exportSize] forKey:@"inputRectangle"];  //give the filter the size to crop to
      croppedImage = [crop valueForKey:@"outputImage"];  //set the output image, note it's still a CIImage at this point
  </code></pre>
  
  <p>Sadly, it's not working.  The image it crops ends up being 0x0 pixels.  A quick NSLog of _exportSize (which is a CGFloat) reveals it's 1024, but the log shows that the image post crop is 0x0.  I cannot work out why.</p>
  
  <p>This code worked before.  The only difference being, I think, is that I used to crop UIImage no CIImages.  I'd rather not have to convert as I plan on doing other CoreImage stuff after the crop.</p>
  
  <p>As I say, _exportSize is a CGFloat _exportSize; and logging it reveals it 1024.0000.</p>
  
  <p>Any ideas?</p>
  
  <p>Cheers.</p>