def get_all_hough_lines(image, min_angle, max_angle, min_separation_distance,
min_separation_angle):
angles = np.deg2rad(np.arange(min_angle, max_angle, 0.5))
hough, angles, distances = hough_line(image, angles)
Debug.save_image("hough", "accumulator", normalize(hough))
_, peak_angles, peak_distances = \
hough_line_peaks(hough, angles, distances,
num_peaks=150,
threshold=0.2*np.amax(hough),
min_distance=min_separation_distance,
min_angle=min_separation_angle)
lines = [
get_line_endpoints_in_image(image, angle, radius)
for angle, radius in zip(peak_angles, peak_distances)
]
if Debug.active:
peak_angle_idxs = [
np.where(angles == angle)[0][0] for angle in peak_angles
]
peak_rho_idxs = [
np.where(distances == distance)[0][0]
for distance in peak_distances
]
peak_coords = zip(peak_rho_idxs, peak_angle_idxs)
peaks = np.zeros(hough.shape)
for coord in peak_coords:
peaks[coord] = 1
Debug.save_image("hough", "accumulator_peaks", peaks)
if Record.active:
# Thought get_max_theta_idx might be a useful way to filter
# real meanlines from spurious meanlines, but it's not
# reliable when the image is saturated with incorrect
# meanlines. Filtering lines based on the ROI angle
# was more effective.
# max_theta_idx = get_max_theta_idx(hough)
# Record.record("theta_mode", angles[max_theta_idx])
# in radians
average_meanline_angle = np.mean(peak_angles)
std_deviation_meanline_angle = np.std(peak_angles)
Record.record("average_meanline_angle",
float("%.4f" % average_meanline_angle))
Record.record("std_deviation_meanline_angle",
float("%.4f" % std_deviation_meanline_angle))
return lines
def get_max_theta_idx(hough):
'''
Returns the column (theta) of the hough transform with the
most above-threshold bins.
'''
thresh_hough = threshold_hough(hough, 0.2 * np.amax(hough))
Debug.save_image("hough", "thresholded_accumulator",
normalize(thresh_hough))
# find the column with the most above-threshold bins
sum_thresh_hough = np.sum(thresh_hough, axis=0)
max_theta_idx = np.argmax(sum_thresh_hough)
return max_theta_idx
def detect_meanlines(masked_image, corners, scale=1):
padding = PARAMS["trace-spacing"](scale) / 2
timeStart("bound image")
# effectively shrink the roi by a distance **padding**
top_bound = padding + np.amax(
[corners["top_left"][1], corners["top_right"][1]])
bottom_bound = -padding + np.amin(
[corners["bottom_left"][1], corners["bottom_right"][1]])
left_bound = padding + np.amax(
[corners["bottom_left"][0], corners["top_left"][0]])
right_bound = -padding + np.amin(
[corners["top_right"][0], corners["bottom_right"][0]])
# mask all image values outside of this shrunken roi
bounded_image = masked_image.copy()
bounded_image[:top_bound, :] = ma.masked
bounded_image[bottom_bound:, :] = ma.masked
bounded_image[:, :left_bound] = ma.masked
bounded_image[:, right_bound:] = ma.masked
timeEnd("bound image")
Debug.save_image("meanlines", "bounded_image", bounded_image.filled(0))
timeStart("threshold image")
black_and_white_image = otsu_threshold_image(bounded_image)
timeEnd("threshold image")
Debug.save_image("meanlines", "thresholded_image", black_and_white_image)
timeStart("remove small objects")
filtered_image = remove_small_objects(black_and_white_image,
PARAMS["small-object-size"](scale))
timeEnd("remove small objects")
Debug.save_image("meanlines", "filtered_image", filtered_image)
timeStart("get hough lines")
roi_top_angle = np.rad2deg(
points_to_rho_theta(corners["top_left"], corners["top_right"])[1])
angle_padding = 2 # degrees
min_angle = roi_top_angle - angle_padding
max_angle = roi_top_angle + angle_padding
min_separation_distance = int((2.0 / 3) * PARAMS["trace-spacing"](scale))
lines = get_all_hough_lines(
filtered_image,
min_angle=min_angle,
max_angle=max_angle,
min_separation_distance=min_separation_distance,
min_separation_angle=5)
timeEnd("get hough lines")
print "found %s meanlines" % len(lines)
Record.record("num_meanlines", len(lines))
if Debug.active:
debug_image = gray2rgb(np.copy(masked_image))
line_coords = [
skidraw.line(line[0][1], line[0][0], line[1][1], line[1][0])
for line in lines
]
for line in line_coords:
rr, cc = line
mask = (rr >= 0) & (rr < debug_image.shape[0]) & (cc >= 0) & (
cc < debug_image.shape[1])
debug_image[rr[mask], cc[mask]] = [1.0, 0, 0]
Debug.save_image("meanlines", "meanlines", debug_image)
return lines