"""
========================
CENSURE feature detector
========================

The CENSURE feature detector is a scale-invariant center-surround detector
(CENSURE) that claims to outperform other detectors and is capable of real-time
implementation.
"""

from skimage import data
from skimage import transform as tf
from skimage.feature import CENSURE
from skimage.color import rgb2gray

import matplotlib.pyplot as plt

img_orig = rgb2gray(data.astronaut())
tform = tf.AffineTransform(scale=(1.5, 1.5), rotation=0.5,
                           translation=(150, -200))
img_warp = tf.warp(img_orig, tform)

detector = CENSURE()

fig, ax = plt.subplots(nrows=1, ncols=2, figsize=(12, 6))
plt.tight_layout()

detector.detect(img_orig)

ax[0].imshow(img_orig, cmap=plt.cm.gray)
ax[0].axis('off')
ax[0].scatter(detector.keypoints[:, 1], detector.keypoints[:, 0],
              2 ** detector.scales, facecolors='none', edgecolors='r')

detector.detect(img_warp)

ax[1].imshow(img_warp, cmap=plt.cm.gray)
ax[1].axis('off')
ax[1].scatter(detector.keypoints[:, 1], detector.keypoints[:, 0],
              2 ** detector.scales, facecolors='none', edgecolors='r')

plt.show()