fig, ax = plt.subplots(2, 2, figsize=(6, 6), subplot_kw={'xticks': [],
    'yticks': []})
fig.subplots_adjust(hspace=0.1, wspace=0.1)
ax = ax.ravel()
cmap1 = CustomCmap([0.0, 0.0, 0.0], [0.02, 0.75, 1.0])
cmap2 = CustomCmap([1.0, 1.0, 1.0], [0.02, 0.75, 1.0])
cmap3 = CustomCmap([1.0, 0.42, 0.04], [0.02, 0.75, 1.0])
cmap4 = CustomCmap([1.0, 0.42, 0.04], [0.5, 0.5, 0.5])
ax[0].imshow(np.random.rand(30, 30), interpolation='none', cmap=cmap1)
ax[1].imshow(np.random.rand(30, 30), interpolation='none', cmap=cmap2)
ax[2].imshow(np.random.rand(30, 30), interpolation='none', cmap=cmap3)
ax[3].imshow(np.random.rand(30, 30), interpolation='none', cmap=cmap4)
matplotlib: single colored colormap with saturation