GridPatch adds patches of constant value and 0, 0 location when the number of required patches is bigger than the patches that can be extracted from the image. The patch location returned in this case should be a List [0, 0] ,to be consistent with the type of the otherwise returned types, while it currently is a List of Lists [[0], [0]].

The reason of this behavior can be seen in this line

The above line should be changed to np.zeros((len(self.patch_size)))