import numpy as np
import holoviews as hv
hv.extension('matplotlib')

def circle(radius):
    angles = np.linspace(0, 2*np.pi, 50)
    return {'x': radius*np.sin(angles), 'y': radius*np.cos(angles), 'radius': radius}

hv.Contours([circle(i) for i in np.linspace(0, 1, 10)], vdims='radius')

x,y = np.mgrid[-50:51, -50:51] * 0.05
img = hv.Image(np.sin(x**2+y**3))
contours = hv.operation.contours(img, levels=5)

img + contours.opts(colorbar=True, cmap='fire')