Visible image joins


I'm trying to display a mosaic of image tiles in a single plot, but I keep
getting lines between the tiles. Is there a way to avoid these lines?
(I'd really rather not pre-process the images to stitch them all together
into a single image.)

The following code reproduces the problem:

import matplotlib.pyplot as plt
import numpy as np

e1 = (27, 31.5, 31.5, 36)
e2 = (31.5, 36, 31.5, 36)

image = np.zeros((10, 10))
for e in (e1, e2):
    plt.imshow(image, extent=e)
plt.xlim(27, 36)

I've also tried the following with no improvement:
    plt.imshow(image, extent=e, interpolation='none', resample=False)

Richard Hattersley