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

ls = np.linspace(0, 10, 200)
xx, yy = np.meshgrid(ls, ls)

bounds=(-1,-1,1,1)   # Coordinate system: (left, bottom, right, top)
img = hv.Image(np.sin(xx)*np.cos(yy), bounds=bounds)
img

img + img[-0.5:0.5, -0.5:0.5]

closest = img.closest((0.1,0.1))
points = hv.Points([closest])

print('The value at position %s is %s' % (closest, img[0.1, 0.1]))

img * points.opts(color='black', marker='x', s=60)

img.sample(x=0) + img.reduce(x=np.mean)