Update FaceNet.py -- Add an example preprocessor

bob/ip/tensorflow_extractor/FaceNet.py

@@ -52,6 +52,23 @@ class FaceNet(object):
         class FaceNetExtractor(FaceNet, Extractor):
             pass
         extractor = FaceNetExtractor()
+
+    And for a preprocessor you can use::
+
+        from bob.bio.face.preprocessor import FaceCrop
+        # This is the size of the image that this model expects
+        CROPPED_IMAGE_HEIGHT = 160
+        CROPPED_IMAGE_WIDTH = 160
+        # eye positions for frontal images
+        RIGHT_EYE_POS = (46, 53)
+        LEFT_EYE_POS = (46, 107)
+        # Crops the face using eye annotations
+        preprocessor = FaceCrop(
+            cropped_image_size=(CROPPED_IMAGE_HEIGHT, CROPPED_IMAGE_WIDTH),
+            cropped_positions={'leye': LEFT_EYE_POS, 'reye': RIGHT_EYE_POS},
+            color_channel='rgb'
+        )
+
     """
 
     def __init__(self,