Answer: matplotlib: binary heat plot

You need what's known as a ListedColorMap:

import numpy as np import matplotlib.pyplot as plt import matplotlib as mpl # random data x = np.random.random_integers(0, 1, (10, 10)) fig, ax = plt.subplots() # define the colors cmap = mpl.colors.ListedColormap(['r', 'k']) # create a normalize object the describes the limits