Images are returned in wrong format (black and white exchanged)

I have just come across a weired thing with respect to the image representation of the MNIST images. When reading the instructions on the MNIST web page: http://yann.lecun.com/exdb/mnist/ it is written there that:

Pixel values are 0 to 255. 0 means background (white), 255 means foreground (black).

which is exactly the opposite to how images are usually stored: black is 0 and white is 255.

So, what do you think, should we change the images to be 255-images in https://gitlab.idiap.ch/bob/bob.db.mnist/blob/929cbe3bec9c8a04cc08202e1b7ce15e1fe86871/bob/db/mnist/query.py#L60, or shall we keep it as it is (since we are not really converting them to images here)? Shall we at least mention this in our documentation?