evaluating with pretrained_imagenet gives lower J_mean and F_mean than reported in paper

[ruppeshnalwaya1993]

I tried evaluating using imagenet pre-trained resent50 model by removing the --resume flag and providing --pretrained-imagenet flag while running test_davis.py. I got a J_mean of 45.2 and F_mean of 48.8 which is lower than what is reported in the paper Table 1 (50.3 and 49.0). How can I reproduce these numbers?