Raul-Ronald_Galea:

I believe these hardcoded values are the means and stds per channel of images in the ImageNet dataset. However, as I will be training on COCO, should these be changed to the means and stds of the COCO dataset? (or, in general, the current training set?)


Yes, these values are taken from ImageNet.
If you are retraining using data from another domain, you could adapt these values (or recalculate them using your dataset). It’s hard to tell, if you’ll see any performance improvement and you would have to run some experiments.



 Raul-Ronald_Galea:

Should I try to lower the learning rate before unfreezing, or perhaps unfreezing progressively, or what other solutions are there?


A high learning rate sounds reasonable, so I would also recommend to lower it.