VNGeneratePersonSegmentationRequest produces mask at different resolution then source image

Trying to use VNGeneratePersonSegmentationRequest.. it seems to work but the output mask isn't at the same resolution as the source image.. so comping the result with the source produces a bad result.

Not the full code, but hopefully enough to see what I'm doing.

var imageRect = CGRect(x: 0, y: 0, width: image.size.width, height: image.size.height)

let imageRef = image.cgImage(forProposedRect: &imageRect, context: nil, hints: nil)!

let request = VNGeneratePersonSegmentationRequest()
let handler = VNImageRequestHandler(cgImage: imageRef)

do {
                        
  try handler.perform([request])                 
  guard let result = request.results?.first else {
    return
  }

  //Is this the right way to do this? 
  let output = result.pixelBuffer           

  //This ciImage alpha mask is a different resolution than the source image 
  //So I don't know how to combine this with the source to cut out the foreground as they don't line up.. the res it's even the right aspect ratio.  
  let ciImage = CIImage(cvPixelBuffer: output)
   .....             
}