matplotlib Code

import numpy as np
import matplotlib.pyplot as plt

d = np.arange(100).reshape(10, 10)
x, y = np.meshgrid(np.arange(11), np.arange(11))

theta = 0.25*np.pi
xx = x*np.cos(theta) - y*np.sin(theta)
yy = x*np.sin(theta) + y*np.cos(theta)

ax1 = plt.subplot(221)
ax1.set_aspect(1)
ax1.pcolormesh(xx, yy, d)
ax1.set_title("No Rasterization")

ax2 = plt.subplot(222)
ax2.set_aspect(1)
ax2.set_title("Rasterization")

m = ax2.pcolormesh(xx, yy, d)
m.set_rasterized(True)

ax3 = plt.subplot(223)
ax3.set_aspect(1)
ax3.pcolormesh(xx, yy, d)
ax3.text(0.5, 0.5, "Text", alpha=0.2,
         va="center", ha="center", size=50, transform=ax3.transAxes)

ax3.set_title("No Rasterization")


ax4 = plt.subplot(224)
ax4.set_aspect(1)
m = ax4.pcolormesh(xx, yy, d)
m.set_zorder(-20)

ax4.text(0.5, 0.5, "Text", alpha=0.2,
         zorder=-15,
         va="center", ha="center", size=50, transform=ax4.transAxes)

ax4.set_rasterization_zorder(-10)

ax4.set_title("Rasterization z$<-10$")


# ax2.title.set_rasterized(True) # should display a warning

plt.savefig("test_rasterization.pdf", dpi=150)
plt.savefig("test_rasterization.eps", dpi=150)

if not plt.rcParams["text.usetex"]:
    plt.savefig("test_rasterization.svg", dpi=150)
    # svg backend currently ignores the dpi