looseCrop 
  loosely crop faces with the given into from the original image Cropping based on pixels, xy, and wh
Return
cropped bitmap
Parameters
bitmap
The to be cropped bitmap, won't recycle
faceInfo 
FaceInfo object uses xy xy with normalized length (0~1)
factor
how loose will the cropping area be compared to the detection bounding box. Default 1, best 1.3