Computes and stores the average and current value. Code imported from https://github.com/pytorch/examples/blob/master/imagenet/main.py#

Center loss. Reference: Wen et al. A Discriminative Feature Learning Approach for Deep Face Recognition. ECCV 2016. Args:

Write console output to external text file. Code imported from https://github.com/Cysu/open-reid/blob/master/reid/utils/logging.py.

LeNet++ as described in the Center Loss paper.

Convert image from RGB to gray level.