f = plt.figure()
grid = ImageGrid(f, 111, 
                 nrows_ncols=(2, 2),
                 direction='column',
                 label_mode="L",
                 cbar_location="right",
                 cbar_mode="single",
                 cbar_size="5%",
                 cbar_pad="3%"
                 )
axarr = np.array(grid).reshape(2, 2)
for ax in axarr.flatten():
    m = ax.imshow(np.random.random(15**2).reshape((15, 15))+0.5, 
           norm=LogNorm(vmax=2, vmin=0.5), cmap='coolwarm')
plt.colorbar(m, cax=grid.cbar_axes[0], format=FormatStrFormatter('%.2f'))

f = plt.figure()
grid = ImageGrid(f, 111,  
                 nrows_ncols=(2, 2),
                 direction='column',
                 label_mode="L",
                 )
axarr = np.array(grid).reshape(2, 2)
for ax in axarr.flatten():
    m = ax.imshow(np.random.random(15**2).reshape((15, 15))+0.5, 
           norm=LogNorm(vmax=2, vmin=0.5), cmap='coolwarm')