Torchivison’s model uses ResNet51+FPN as a feature extractor.
I usually transform images by first converting them to a tensor, and then multiplying again by 255
    t_ = transforms.Compose([
                    transforms.ToPILImage(),
                    transforms.Resize(img_size),
                    transforms.ToTensor(),
                    transforms.Normalize(mean=[0.407, 0.457, 0.485],
                    std=[1,1,1])])
   
   img = 255*t_(img)

When I did that with an image input to Faster R-CNN, the result was None, but when I removed the multiplication, it seems to be working fine. It that a ResNet thing?