Simple RGB

import matplotlib.pyplot as plt

from mpl_toolkits.axes_grid1.axes_rgb import RGBAxes


def get_demo_image():
    import numpy as np
    from matplotlib.cbook import get_sample_data
    f = get_sample_data("axes_grid/bivariate_normal.npy", asfileobj=False)
    z = np.load(f)
    # z is a numpy array of 15x15
    return z, (-3, 4, -4, 3)


def get_rgb():
    Z, extent = get_demo_image()

    Z[Z < 0] = 0.
    Z = Z / Z.max()

    R = Z[:13, :13]
    G = Z[2:, 2:]
    B = Z[:13, 2:]

    return R, G, B


fig = plt.figure(1)
ax = RGBAxes(fig, [0.1, 0.1, 0.8, 0.8])

r, g, b = get_rgb()
kwargs = dict(origin="lower", interpolation="nearest")
ax.imshow_rgb(r, g, b, **kwargs)

ax.RGB.set_xlim(0., 9.5)
ax.RGB.set_ylim(0.9, 10.6)

plt.show()