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https://github.com/wassname/scikit-image.git
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Transferring all the FAST code to corner.py and corner_cy.pyx
This commit is contained in:
Ankit Agrawal
committed by
Johannes Schönberger
Johannes Schönberger
parent
5a886e69c3
commit
b8958ccee0
@@ -102,9 +102,6 @@ Library:
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Extension: skimage.feature.corner_cy
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Sources:
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skimage/feature/corner_cy.pyx
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Extension: skimage.feature.fast_cy
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Sources:
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skimage/feature/fast_cy.pyx
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Extension: skimage.feature._texture
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Sources:
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skimage/feature/_texture.pyx
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@@ -4,13 +4,12 @@ from .texture import greycomatrix, greycoprops, local_binary_pattern
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from .peak import peak_local_max
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from .corner import (corner_kitchen_rosenfeld, corner_harris,
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corner_shi_tomasi, corner_foerstner, corner_subpix,
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corner_peaks)
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corner_peaks, corner_fast)
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from .corner_cy import corner_moravec
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from .template import match_template
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from ._brief import brief, match_keypoints_brief
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from .util import pairwise_hamming_distance
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from .censure import keypoints_censure
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from .fast import corner_fast
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__all__ = ['daisy',
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'hog',
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@@ -1,10 +1,13 @@
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import numpy as np
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from scipy import ndimage
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from scipy import stats
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from scipy.ndimage.filters import maximum_filter
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from skimage.color import rgb2grey
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from skimage.util import img_as_float, pad
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from skimage.feature import peak_local_max
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from corner_cy import _corner_fast
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def _compute_derivatives(image):
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"""Compute derivatives in x and y direction using the Sobel operator.
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@@ -542,3 +545,49 @@ def corner_peaks(image, min_distance=10, threshold_abs=0, threshold_rel=0.1,
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return np.transpose(peaks.nonzero())
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else:
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return peaks
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def corner_fast(image, n=12, threshold=0.15):
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"""Extract FAST corners for a given image.
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Parameters
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----------
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image : 2D ndarray
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Input image.
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n : int
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Number of consecutive pixels out of 16 pixels on the circle that
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should be brighter or darker with respect to test pixel above the
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`threshold` so as to classify the test pixel as a FAST corner. Also
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stands for the n in `FAST-n` corner detector.
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threshold : float
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Threshold used in deciding whether the pixels on the circle are
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brighter, darker or similar w.r.t. the test pixel. Decrease the
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threshold when more corners are desired and vice-versa.
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Returns
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-------
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corners : (N, 2) ndarray
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Location i.e. (row, col) of extracted FAST corners.
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References
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----------
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.. [1] Edward Rosten and Tom Drummond
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"Machine Learning for high-speed corner detection",
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http://www.edwardrosten.com/work/rosten_2006_machine.pdf
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"""
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image = np.squeeze(image)
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if image.ndim != 2:
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raise ValueError("Only 2-D gray-scale images supported.")
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image = np.ascontiguousarray(image, dtype=np.double)
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corner_response = _corner_fast(image, n, threshold)
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# Non-maximal Suppression
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corner_zero_mask = corner_response != 0
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maximas = (maximum_filter(corner_response, (3, 3)) == corner_response) & corner_zero_mask
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x, y = np.where(maximas == True)
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corners = np.squeeze(np.dstack((x, y)))
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return corners
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@@ -80,3 +80,93 @@ def corner_moravec(image, Py_ssize_t window_size=1):
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out[r, c] = min_msum
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return np.asarray(out)
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def _corner_fast(double[:, ::1] image, int n, double threshold):
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cdef int[:] rp = (np.round(3 * np.sin(2 * np.pi * np.arange(16, dtype=np.double) / 16))).astype(np.int32)
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cdef int[:] cp = (np.round(3 * np.cos(2 * np.pi * np.arange(16, dtype=np.double) / 16))).astype(np.int32)
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cdef Py_ssize_t rows = image.shape[0]
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cdef Py_ssize_t cols = image.shape[1]
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cdef Py_ssize_t i, j, k, l, m
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cdef char[:] bins = np.zeros(16, dtype=np.uint8)
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cdef int consecutive_count, speed_sum_b, speed_sum_d
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cdef int sp
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cdef double sum_b, sum_d, current_pixel
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cdef double[:, ::1] corner_response = np.zeros((rows, cols), dtype=np.double)
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cdef double circle_intensity
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for i in range(3, rows - 3):
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for j in range(3, cols - 3):
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current_pixel = image[i, j]
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speed_sum_b = 0
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speed_sum_d = 0
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sum_b = 0
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sum_d = 0
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for k in range(16):
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circle_intensity = image[i + rp[k], j + cp[k]]
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if circle_intensity > current_pixel + threshold:
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# Brighter pixel
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bins[k] = 'b'
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elif circle_intensity < current_pixel - threshold:
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# Darker pixel
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bins[k] = 'd'
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else:
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# Similar pixel
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bins[k] = 's'
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# High speed test for n>=12
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if n >= 12:
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for k in range(0, 16, 4):
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if bins[k] == 'b':
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speed_sum_b += 1
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elif bins[k] == 'd':
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speed_sum_d += 1
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if speed_sum_d < 3 and speed_sum_b < 3:
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continue
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consecutive_count = 0
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for l in range(15 + n):
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if bins[l % 16] == 'b':
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consecutive_count += 1
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if consecutive_count == n:
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for m in range(16):
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if bins[m] == 'b':
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sum_b += image[i + rp[m], j + cp[m]] - current_pixel - threshold
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elif bins[m] == 'd':
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sum_d += current_pixel - image[i + rp[m], j + cp[m]] - threshold
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# Finding the response of the corner
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if sum_d > sum_b:
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corner_response[i, j] = sum_d
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else:
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corner_response[i, j] = sum_b
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break
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else:
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consecutive_count = 0
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if corner_response[i, j] == 0:
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consecutive_count = 0
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for l in range(15 + n):
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if bins[l % 16] == 'd':
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consecutive_count += 1
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if consecutive_count == n:
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for m in range(16):
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if bins[m] == 'b':
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sum_b += image[i + rp[m], j + cp[m]] - current_pixel - threshold
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elif bins[m] == 'd':
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sum_d += current_pixel - image[i + rp[m], j + cp[m]] - threshold
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# Finding the response of the corner
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if sum_d > sum_b:
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corner_response[i, j] = sum_d
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else:
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corner_response[i, j] = sum_b
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break
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else:
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consecutive_count = 0
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return np.asarray(corner_response)
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@@ -14,7 +14,6 @@ def configuration(parent_package='', top_path=None):
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cython(['corner_cy.pyx'], working_path=base_path)
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cython(['censure_cy.pyx'], working_path=base_path)
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cython(['fast_cy.pyx'], working_path=base_path)
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cython(['_brief_cy.pyx'], working_path=base_path)
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cython(['_texture.pyx'], working_path=base_path)
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cython(['_template.pyx'], working_path=base_path)
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@@ -23,8 +22,6 @@ def configuration(parent_package='', top_path=None):
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include_dirs=[get_numpy_include_dirs()])
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config.add_extension('censure_cy', sources=['censure_cy.c'],
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include_dirs=[get_numpy_include_dirs()])
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config.add_extension('fast_cy', sources=['fast_cy.c'],
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include_dirs=[get_numpy_include_dirs()])
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config.add_extension('_brief_cy', sources=['_brief_cy.c'],
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include_dirs=[get_numpy_include_dirs()])
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config.add_extension('_texture', sources=['_texture.c'],
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