Core Image: after using CICrop, applying a compositing filter doesn't line up

I figured out the answer to this... and it's an easy one. I just needed to apply a "Translation" transform on the CIImage after cropping it, like so:

imageToFilter = [imageToFilter imageByApplyingTransform:CGAffineTransformMakeTranslation(0, -imageToFilter.extent.origin.y)];

That effectively moves its y origin back to 0.