fixed scale_factor calculation for uint8 tensor (#31778)
Summary:
When calling the add_images() method on the tensorboard SummaryWriter with a uint8 NCHW tensor, the tensor is incorrectly scaled, resulting in overflow behavior. This leads to incorrect images being displayed in tensorboard.
Issue: https://github.com/pytorch/pytorch/issues/31459
Local Testing (ran this code with and without the PR changes and printed scale_factor):
import torch
import torchvision
from torch.utils.tensorboard import SummaryWriter
writer = SummaryWriter()
x=torch.tensor([[[[1, 2, 3], [4, 5, 6]]]], dtype=torch.uint8)
writer.add_images("images", x)
Before- scale_factor: 255, After- scale_factor: 1
Pull Request resolved: https://github.com/pytorch/pytorch/pull/31778
Differential Revision: D19289189
Pulled By: anjali411
fbshipit-source-id: 350a1650337244deae4fd8f8b7fb0e354ae6986b
