Image loader RGB transform
While loading your images, you could use Image.open(path).convert('RGB') on all images.
If you are using ImageFolder, this functionality should be already there using the default loader.
def myloader(filename):
return Image.open(filename).convert('RGB')
dog_test = datasets.ImageFolder('/data/dog_images/test',transform = valid_transform,loader=myloader)
test = torch.utils.data.DataLoader(dataset=dog_test,batch_size=64)