def update_mark_alpha_channel( mark: torch.Tensor, mark_background_color: torch.Tensor | None = None ) -> torch.Tensor: if mark_background_color is None: return mark mark = mark.clone() mark_background_color = mark_background_color.view(-1, 1, 1) mark[-1] = ~mark[:-1].isclose(mark_background_color, atol=1e-3).all(dim=0) return mark