Error with functional image rotation

I try to rotate an image using torchvision.transforms.functional.rotate and I get this error:

  File "C:\Users\User\Documents\programming\proj\", line 55, in __call__
    image = torchvision.transforms.functional.rotate(PIL_image, angle)
  File "C:\Users\User\Anaconda3\envs\surv\lib\site-packages\torchvision\transforms\", line 729, in rotate
    return img.rotate(angle, resample, expand, center, fillcolor=fill)
  File "C:\Users\User\Anaconda3\envs\surv\lib\site-packages\PIL\", line 1915, in rotate
  File "C:\Users\User\Anaconda3\envs\surv\lib\site-packages\PIL\", line 2205, in transform
    im = new(self.mode, size, fillcolor)
  File "C:\Users\User\Anaconda3\envs\surv\lib\site-packages\PIL\", line 2375, in new
    return Image()._new(core.fill(mode, size, color))
TypeError: must be real number, not tuple

If I do PIL_image.rotate(angle) it works (using PIL’s rotation utility), but for some reason using pytorch’s torchvision.transforms.functional.rotate gives an error. How should I resolve this?


I believe this occurs when your image is mode = F (floating point) and thus only has a single channel. In this case color is expected to be a single number and not a tuple. Pytorch however sees floating point numbers and passes a tuple of one item downstream to color and hence the error from PIL. Not sure if it’s a bug or a feature.

It sounds rather like a bug.
@agt could you confirm @pford221’s assumption?

I am also facing simular issue

I’m getting a similar issue as well! My model was working perfectly a few days ago, and I don’t think I’ve changed anything, but I’m seeing the following when I try to run the model:

/usr/lib/python3/dist-packages/PIL/ in expand(image, border, fill)
360 width = left + image.size[0] + right
361 height = top + image.size[1] + bottom
–> 362 out =, (width, height), _color(fill, image.mode))
363 out.paste(image, (left, top))
364 return out

/usr/lib/python3/dist-packages/PIL/ in new(mode, size, color)
2542 im.palette = ImagePalette.ImagePalette()
2543 color = im.palette.getcolor(color)
-> 2544 return im._new(core.fill(mode, size, color))

TypeError: must be real number, not tuple

Could this be a new bug? I’m processing .tif images and each of the images are going through the following transform:

def transform_function(degrees,scale,flip_prob):

transform_list.append(transforms.RandomAffine(degrees, scale = scale))
transform_list.append(transforms.Pad(37)) #all images should be 182x182 before padding.