Forget to ignore class 255 in caculating mIoU?

[liheyoung]

Forget to ignore class 255 in caculating mIoU?

[Haochen-Wang409]

I'm also confused here. It seems like label 255 in GT will be replaced to background (label 0) for further evaluation.

[LiheYoung]

Hi, @pascal1129 and @Haochen-Wang409

The class 255 is ignored in calculating the mIOU.

The mask defined here indicates the valid regions that do not contain the 255 value, since the self.num_classes is only 21 for Pascal VOC dataset. In the following confusion matrix computation, both groundtruth mask (label_true) and predicted mask (label_pred) are filtered with the valid regions (mask).

ST-PlusPlus/utils.py

Lines 18 to 19 in 7c31abf

	self.num_classes * label_true[mask].astype(int) +
	label_pred[mask], minlength=self.num_classes ** 2).reshape(self.num_classes, self.num_classes)