Inter-pupil Distance (IPD) is the distance between the center of the two eyes, or\(\text{IPD}=\ \sqrt{{(r_{x}-l_{x})}^{2}+{(r_{\text{y\ }}-\ l_{y})}^{2}}\text{.\ }\)We scaled each image automatically so that each eye would be\(0.5\times\text{IPD}\) away from the closest side edge and\(0.6\times\text{IPD}\) away from the top edge of the cropped face image. We chose these values by sampling 30 seal images and determining the optimum face to background ratio for facial recognition.

Thus, at the end of this step, each face image was rotated and resized to 112x112 pixels in preparation for facial recognition. The name of each of these images will contain information about its original image and the location within the original image from which it was chipped.