About the region loss

[igodrr]

Hi authers:
About the region loss
loss_dict["loss_region"] = loss_func( out_region * gt_mask_region[:, None], gt_region * gt_mask_region.long() ) / gt_mask_region.sum().float().clamp(min=1.0)
I think out_region * gt_mask_region[:, None] can't remove the loss of background. This operation makes all the channels of the background point to 0, which will all become 1/65 after passing through the softmax of CE_LOSS.
I don't know if my understanding is correct, hope to get your reply! Thanks very much!

[wangg12]

Hi, this formulation does not remove the loss of background, but tries to map the background to a "background" region. For truly remove the background loss, one might need to use the "ignore" trick. You can try that out. But I think it would not make a big difference.

[igodrr]

Hi, thanks for your reply! But I think this can't map the background to a "background" region as I mentioned above, make all the channels of a pixel to 0 will make them all become 1/65 after passing through the softmax, so the loss of this "background pixel" is log(1/65). I don't quite understand what you mean by mapping the background into the "background" area. Is the purpose of this operation to eliminate the interference of the background? If yes, why not just ignore it?
Looking forward to your reply! Thanks very much!