def _erfimage_imshow(ax, ch_idx, tmin, tmax, vmin, vmax, ylim=None, data=
    None, epochs=None, sigma=None, order=None, scalings=None, vline=None,
    x_label=None, y_label=None, colorbar=False, cmap='RdBu_r', vlim_array=None
    ):
    """Plot erfimage on sensor topography."""
    from scipy import ndimage
    import matplotlib.pyplot as plt
    this_data = data[:, (ch_idx), :]
    if vlim_array is not None:
        vmin, vmax = vlim_array[ch_idx]
    if callable(order):
        order = order(epochs.times, this_data)
    if order is not None:
        this_data = this_data[order]
    if sigma > 0.0:
        this_data = ndimage.gaussian_filter1d(this_data, sigma=sigma, axis=0)
    img = ax.imshow(this_data, extent=[tmin, tmax, 0, len(data)], aspect=
        'auto', origin='lower', vmin=vmin, vmax=vmax, picker=True, cmap=
        cmap, interpolation='nearest')
    ax = plt.gca()
    if x_label is not None:
        ax.set_xlabel(x_label)
    if y_label is not None:
        ax.set_ylabel(y_label)
    if colorbar:
        plt.colorbar(mappable=img)
