/
util.py
160 lines (120 loc) · 4.62 KB
/
util.py
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import numpy as np
from ..util import img_as_float
from .._shared.utils import assert_nD
class FeatureDetector(object):
def __init__(self):
self.keypoints_ = np.array([])
def detect(self, image):
"""Detect keypoints in image.
Parameters
----------
image : 2D array
Input image.
"""
raise NotImplementedError()
class DescriptorExtractor(object):
def __init__(self):
self.descriptors_ = np.array([])
def extract(self, image, keypoints):
"""Extract feature descriptors in image for given keypoints.
Parameters
----------
image : 2D array
Input image.
keypoints : (N, 2) array
Keypoint locations as ``(row, col)``.
"""
raise NotImplementedError()
def plot_matches(ax, image1, image2, keypoints1, keypoints2, matches,
keypoints_color='k', matches_color=None, only_matches=False):
"""Plot matched features.
Parameters
----------
ax : matplotlib.axes.Axes
Matches and image are drawn in this ax.
image1 : (N, M [, 3]) array
First grayscale or color image.
image2 : (N, M [, 3]) array
Second grayscale or color image.
keypoints1 : (K1, 2) array
First keypoint coordinates as ``(row, col)``.
keypoints2 : (K2, 2) array
Second keypoint coordinates as ``(row, col)``.
matches : (Q, 2) array
Indices of corresponding matches in first and second set of
descriptors, where ``matches[:, 0]`` denote the indices in the first
and ``matches[:, 1]`` the indices in the second set of descriptors.
keypoints_color : matplotlib color, optional
Color for keypoint locations.
matches_color : matplotlib color, optional
Color for lines which connect keypoint matches. By default the
color is chosen randomly.
only_matches : bool, optional
Whether to only plot matches and not plot the keypoint locations.
"""
image1 = img_as_float(image1)
image2 = img_as_float(image2)
new_shape1 = list(image1.shape)
new_shape2 = list(image2.shape)
if image1.shape[0] < image2.shape[0]:
new_shape1[0] = image2.shape[0]
elif image1.shape[0] > image2.shape[0]:
new_shape2[0] = image1.shape[0]
if image1.shape[1] < image2.shape[1]:
new_shape1[1] = image2.shape[1]
elif image1.shape[1] > image2.shape[1]:
new_shape2[1] = image1.shape[1]
if new_shape1 != image1.shape:
new_image1 = np.zeros(new_shape1, dtype=image1.dtype)
new_image1[:image1.shape[0], :image1.shape[1]] = image1
image1 = new_image1
if new_shape2 != image2.shape:
new_image2 = np.zeros(new_shape2, dtype=image2.dtype)
new_image2[:image2.shape[0], :image2.shape[1]] = image2
image2 = new_image2
image = np.concatenate([image1, image2], axis=1)
offset = image1.shape
if not only_matches:
ax.scatter(keypoints1[:, 1], keypoints1[:, 0],
facecolors='none', edgecolors=keypoints_color)
ax.scatter(keypoints2[:, 1] + offset[1], keypoints2[:, 0],
facecolors='none', edgecolors=keypoints_color)
ax.imshow(image, interpolation='nearest', cmap='gray')
ax.axis((0, 2 * offset[1], offset[0], 0))
for i in range(matches.shape[0]):
idx1 = matches[i, 0]
idx2 = matches[i, 1]
if matches_color is None:
color = np.random.rand(3)
else:
color = matches_color
ax.plot((keypoints1[idx1, 1], keypoints2[idx2, 1] + offset[1]),
(keypoints1[idx1, 0], keypoints2[idx2, 0]),
'-', color=color)
def _prepare_grayscale_input_2D(image):
image = np.squeeze(image)
assert_nD(image, 2)
return img_as_float(image)
def _mask_border_keypoints(image_shape, keypoints, distance):
"""Mask coordinates that are within certain distance from the image border.
Parameters
----------
image_shape : (2, ) array_like
Shape of the image as ``(rows, cols)``.
keypoints : (N, 2) array
Keypoint coordinates as ``(rows, cols)``.
distance : int
Image border distance.
Returns
-------
mask : (N, ) bool array
Mask indicating if pixels are within the image (``True``) or in the
border region of the image (``False``).
"""
rows = image_shape[0]
cols = image_shape[1]
mask = (((distance - 1) < keypoints[:, 0])
& (keypoints[:, 0] < (rows - distance + 1))
& ((distance - 1) < keypoints[:, 1])
& (keypoints[:, 1] < (cols - distance + 1)))
return mask