Fig 2.

(a) A rodent image example. (b) The skull region of the rodent image with bounding box (the blue rectangle) and bregma/lambda masks (the red/green circles) manually labeled. In the red and green circles, the closer a pixel is to bregma/lambda point, the larger the value (i.e., brighter) is assigned to the labeled pixel. Therefore, the edges of the two circles are dark while the center is bright. The bounding box is used to train the faster-rcnn in stage one, and bregma/lambda masks are used to train the FCN in stage two.