why plotting a (112,112,2) in matplotlib using imshow() is not possible?

Question

why is it that we can not plot a matrix that has the shape (112,112,2) but doing it for shapes such as (112,112,3)is ok ?

TypeError: Invalid shape (112, 112, 2) for image data

why doesn't this error come up when trying to plot a (112,112,3) matrix ?

010101010101010101010100101010101010101010011010101010010101010101010

UPDATE I get this image from the web(address of the image

and use plt.imread() to turn the image into matrix. and then use plt.matshow() to plot it. this is the result:

so far so good, after doing 3dmaxpooling on the image:

def maxpooling3d(image_path,stride):
"""
image_path = the URL or the directory path of the image
stride = the strides for 3d data i.e (2,2,2)
"""

#MATRIXIFY THE DATA AND GET THEIR DIMENSIONS 
image_matrix = plt.imread(image_path)
d1,d2,d3 = image_matrix.shape

#RESHAPE IT 
image_matrix_reshaped = image_matrix.reshape(1,d1,d2,d3,1)

#MAXPOOL THE RESHAPED IMAGE MATRIX
max_pool = tf.keras.layers.MaxPooling3D(strides=stride)
model = tf.keras.Sequential([max_pool])
result = model.predict(image_matrix_reshaped)
return np.squeeze(result)

and then get the result :

result_matrix = maxpooling3d(image_path,(2,2,2))

now that I want to plot the maxpooled matrix, I get this error:

TypeError                                 Traceback (most recent call last)
<ipython-input-249-941479181323> in <module>
----> 1 plt.matshow(result_matrix)

e:\Users\Keram\anaconda3\lib\site-packages\matplotlib\pyplot.py in matshow(A, fignum, **kwargs)
   2299         fig = figure(fignum, figsize=figaspect(A))
   2300         ax = fig.add_axes([0.15, 0.09, 0.775, 0.775])
-> 2301     im = ax.matshow(A, **kwargs)
   2302     sci(im)
   2303     return im

e:\Users\Keram\anaconda3\lib\site-packages\matplotlib\axes\_axes.py in matshow(self, Z, **kwargs)
   7751               'aspect': 'equal',          # (already the imshow default)
   7752               **kwargs}
-> 7753         im = self.imshow(Z, **kw)
   7754         self.title.set_y(1.05)
   7755         self.xaxis.tick_top()

e:\Users\Keram\anaconda3\lib\site-packages\matplotlib\__init__.py in inner(ax, data, *args, **kwargs)
   1445     def inner(ax, *args, data=None, **kwargs):
   1446         if data is None:
-> 1447             return func(ax, *map(sanitize_sequence, args), **kwargs)
   1448 
   1449         bound = new_sig.bind(ax, *args, **kwargs)

e:\Users\Keram\anaconda3\lib\site-packages\matplotlib\axes\_axes.py in imshow(self, X, cmap, norm, aspect, interpolation, alpha, vmin, vmax, origin, extent, filternorm, filterrad, resample, url, **kwargs)
   5521                               resample=resample, **kwargs)
   5522 
-> 5523         im.set_data(X)
   5524         im.set_alpha(alpha)
   5525         if im.get_clip_path() is None:

e:\Users\Keram\anaconda3\lib\site-packages\matplotlib\image.py in set_data(self, A)
    709         if not (self._A.ndim == 2
    710                 or self._A.ndim == 3 and self._A.shape[-1] in [3, 4]):
--> 711             raise TypeError("Invalid shape {} for image data"
    712                             .format(self._A.shape))
    713 

TypeError: Invalid shape (256, 256, 2) for image data