Files
scikit-image/doc/examples/plot_censure_keypoints.py
T
2013-08-15 15:15:41 +05:30

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Python

"""
===========================
Censure Keypoints Detection
===========================
In this example, we detect and plot the Censure Keypoints at various scales
using Difference of Boxes, Octagon and Star shaped bi-level filters.
"""
from skimage.feature import keypoints_censure
from skimage.data import lena
from skimage.color import rgb2gray
import matplotlib.pyplot as plt
# Initializing the parameters for Censure keypoints
img = lena()
gray_img = rgb2gray(img)
min_scale = 1
max_scale = 7
nms_threshold = 0.15
rpc_threshold = 10
# Detecting Censure keypoints for the following filters
for mode in ['dob', 'octagon', 'star']:
kp_censure, scale = keypoints_censure(gray_img, min_scale, max_scale,
mode, nms_threshold, rpc_threshold)
f, axarr = plt.subplots((max_scale - min_scale + 1) // 3, 3)
# Plotting Censure features at all the scales
for i in range(max_scale - min_scale - 1):
keypoints = kp_censure[scale == i + min_scale + 1]
num = len(keypoints)
x = keypoints[:, 1]
y = keypoints[:, 0]
s = 5 * 2**(i + min_scale + 1)
axarr[i // 3, i - (i // 3) * 3].imshow(img)
axarr[i // 3, i - (i // 3) * 3].scatter(x, y, s, facecolors='none',
edgecolors='g')
axarr[i // 3, i - (i // 3) * 3].set_title(' %s %s-Censure features at '
'scale %d' % (num, mode, i +
min_scale + 1))
plt.suptitle('NMS threshold = %f, RPC threshold = %d'
% (nms_threshold, rpc_threshold))
plt.show()