def apply_found_rotation_or_skew(self, rot_or_skew_type,
rot_or_skew_radians):
"""
Apply a found page rotation or skew to the detected lines in order to fix their rotation / skew.
You can pass the output of find_rotation_or_skew into this method.
"""
if rot_or_skew_type is None or rot_or_skew_radians is None:
return self.lines_hough
if rot_or_skew_type == ROTATION:
filter_line_dir = None
else: # skew
filter_line_dir = DIRECTION_HORIZONTAL if rot_or_skew_type == SKEW_Y else DIRECTION_VERTICAL
lines_hough_deskewed = []
for rho, theta, theta_norm, line_dir in self.lines_hough:
if filter_line_dir is None or (filter_line_dir is not None
and line_dir == filter_line_dir):
theta += rot_or_skew_radians
theta_norm = normalize_angle(theta)
lines_hough_deskewed.append((rho, theta, theta_norm, line_dir))
self.lines_hough = lines_hough_deskewed
return self.lines_hough
def _generate_hough_lines(self, lines):
"""
From a list of lines in <lines> detected by cv2.HoughLines, create a list with a tuple per line
containing:
(rho, theta, normalized theta with 0 <= theta_norm < np.pi, DIRECTION_VERTICAL or DIRECTION_HORIZONTAL)
"""
lines_hough = []
for l in lines:
rho, theta = l[0] # they come like this from OpenCV's hough transform
theta_norm = normalize_angle(theta)
if abs(PIHLF - theta_norm) > PI4TH: # vertical
line_dir = DIRECTION_VERTICAL
else:
line_dir = DIRECTION_HORIZONTAL
lines_hough.append((rho, theta, theta_norm, line_dir))
return lines_hough
def _generate_hough_lines(self, lines):
"""
From a list of lines in <lines> detected by cv2.HoughLines, create a list with a tuple per line
containing:
(rho, theta, normalized theta with 0 <= theta_norm < np.pi, DIRECTION_VERTICAL or DIRECTION_HORIZONTAL)
"""
lines_hough = []
for l in lines:
rho, theta = l[0] # they come like this from OpenCV's hough transform
theta_norm = normalize_angle(theta)
if abs(PIHLF - theta_norm) > PI4TH: # vertical
line_dir = DIRECTION_VERTICAL
else:
line_dir = DIRECTION_HORIZONTAL
lines_hough.append((rho, theta, theta_norm, line_dir))
return lines_hough
def apply_found_rotation_or_skew(self, rot_or_skew_type, rot_or_skew_radians):
"""
Apply a found page rotation or skew to the detected lines in order to fix their rotation / skew.
You can pass the output of find_rotation_or_skew into this method.
"""
if rot_or_skew_type is None or rot_or_skew_radians is None:
return self.lines_hough
if rot_or_skew_type == ROTATION:
filter_line_dir = None
else: # skew
filter_line_dir = DIRECTION_HORIZONTAL if rot_or_skew_type == SKEW_Y else DIRECTION_VERTICAL
lines_hough_deskewed = []
for rho, theta, theta_norm, line_dir in self.lines_hough:
if filter_line_dir is None or (filter_line_dir is not None and line_dir == filter_line_dir):
theta += rot_or_skew_radians
theta_norm = normalize_angle(theta)
lines_hough_deskewed.append((rho, theta, theta_norm, line_dir))
self.lines_hough = lines_hough_deskewed
return self.lines_hough
def test_normalize_angle():
for i in range(-10, 10):
theta = i * np.pi
norm = normalize_angle(theta)
assert 0 <= norm < 2 * np.pi
assert norm / np.pi == i % 2