Efficient method of calculating density of irregularly spaced points

This approach is along the lines of some previous answers: increment a pixel for each spot, then smooth the image with a gaussian filter. A 256×256 image runs in about 350ms on my 6-year-old laptop.

import numpy as np
import scipy.ndimage as ndi

data = np.random.rand(30000,2)           ## create random dataset
inds = (data * 255).astype('uint')       ## convert to indices

img = np.zeros((256,256))                ## blank image
for i in xrange(data.shape[0]):          ## draw pixels
    img[inds[i,0], inds[i,1]] += 1

img = ndi.gaussian_filter(img, (10,10))