How to create a figure with no axes ( frameless ) or labels using matplotlib ?

With matplotlib it is possible to create and save a figure with no axes and labels. For example, let's consider the following figure (source)

#!/usr/bin/env python
import numpy as np
import matplotlib.cm as cm
import matplotlib.mlab as mlab
import matplotlib.pyplot as plt

delta = 0.025
x = y = np.arange(-3.0, 3.0, delta)
X, Y = np.meshgrid(x, y)
Z1 = mlab.bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
Z2 = mlab.bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
Z = Z2-Z1  # difference of Gaussians

im = plt.imshow(Z, interpolation='bilinear', cmap=cm.RdYlGn,
                origin='lower', extent=[-3,3,-3,3],
                vmax=abs(Z).max(), vmin=-abs(Z).max())

plt.show()

After removing the frame:

#!/usr/bin/env python
import numpy as np
import matplotlib.cm as cm
import matplotlib.mlab as mlab
import matplotlib.pyplot as plt

my_dpi=100

fig = plt.figure(figsize=(800/my_dpi, 800/my_dpi), dpi=my_dpi)

ax = plt.Axes(fig, [0., 0., 1., 1.])
ax.set_axis_off()
fig.add_axes(ax)

delta = 0.025
x = y = np.arange(-3.0, 3.0, delta)
X, Y = np.meshgrid(x, y)
Z1 = mlab.bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
Z2 = mlab.bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
Z = Z2-Z1  # difference of Gaussians

im = plt.imshow(Z, interpolation='bilinear', cmap=cm.RdYlGn,
                origin='lower', extent=[-3,3,-3,3],
                vmax=abs(Z).max(), vmin=-abs(Z).max())

fig.savefig('MatplotlibImageNoFrame02.png', dpi=my_dpi)
plt.show()

Another example:

#!/usr/bin/env python
import numpy as np
import matplotlib.cm as cm
import matplotlib.mlab as mlab
import matplotlib.pyplot as plt

my_dpi=100

delta = 0.025
x = y = np.arange(-3.0, 3.0, delta)
X, Y = np.meshgrid(x, y)
Z1 = mlab.bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
Z2 = mlab.bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
Z = Z2-Z1  # difference of Gaussians

Shape = Z.shape

fig = plt.figure(figsize=(Shape[1]/my_dpi, Shape[0]/my_dpi), dpi=my_dpi)

ax = plt.Axes(fig, [0., 0., 1., 1.])
ax.set_axis_off()
fig.add_axes(ax)

im = plt.imshow(Z, interpolation='bilinear', cmap=cm.RdYlGn,
                origin='lower', extent=[-3,3,-3,3],
                vmax=abs(Z).max(), vmin=-abs(Z).max())

fig.savefig('MatplotlibImageNoFrame02.png', dpi=my_dpi)
plt.show()

References