tensor_convert_rgb is typed for NHWC torch tensors, but with prefer_copy it called image.copy(), which torch.Tensor does not have, so every RGBA image raised AttributeError. Use clone() for a tensor and keep copy() for a numpy array.
Fixes#1194, fixes#1178.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>