Boolean indexing is indexing based on a boolean array and falls under the category of fancy indexing.
We will apply this indexing technique to an image:
This is in some way similar to the Fancy indexing recipe in this chapter. This time, we select modulo
4 points on the diagonal of the image:
def get_indices(size): arr = np.arange(size) return arr % 4 == 0
Then we just apply this selection and plot the points:
lena1 = lena.copy() xindices = get_indices(lena.shape) yindices = get_indices(lena.shape) lena1[xindices, yindices] = 0 plt.subplot(211) plt.imshow(lena1)
lena2[(lena > lena.max()/4) ...