def suppression(img, D, t):
""" Step 3: Non-maximum suppression(code contains threshold)
Args:
img: Numpy ndarray of image to be processed (gradient-intensed image)
D: Numpy ndarray of gradient directions for each pixel in img
Returns:
...
"""
M, N = img.shape
Z = np.zeros((M, N), dtype=np.int32)
DZ = np.zeros((M, N), dtype=np.int32)
for i in range(1, M - 1):
for j in range(1, N - 1):
# find neighbour pixels to visit from the gradient directions
if abs(img[i, j]) > t:
where = round_angle(D[i, j])
try:
if where == 0:
if (img[i, j] >= img[i, j - 1]) and (img[i, j] >=
img[i, j + 1]):
Z[i, j] = img[i, j]
DZ[i, j] = D[i, j]
elif where == 90:
if (img[i, j] >= img[i - 1, j]) and (img[i, j] >=
img[i + 1, j]):
Z[i, j] = img[i, j]
DZ[i, j] = D[i, j]
elif where == 135:
if (img[i, j] >= img[i - 1, j + 1]) and (
img[i, j] >= img[i + 1, j - 1]):
Z[i, j] = img[i, j]
DZ[i, j] = D[i, j]
elif where == 45:
if (img[i, j] >= img[i + 1, j + 1]) and (
img[i, j] >= img[i - 1, j - 1]):
Z[i, j] = img[i, j]
DZ[i, j] = D[i, j]
except IndexError as e:
""" Todo: Deal with pixels at the image boundaries. """
pass
return Z, DZ
def sharp_curve_remove(img, D, min_pixel, t):
""" Step 3: sharp_curve_remove
Args:
img: Numpy ndarray of image to be processed (gradient-intensed image)
D: Numpy ndarray of gradient directions for each pixel in img
n: Num of minimal pixels in a line(with same gradient direction)
min_pixel:
t: Minimal gradient of edge
Returns:
...
"""
M, N = img.shape
Z = np.zeros((M, N), dtype=np.int32)
for i in range(M):
for j in range(N):
# find neighbour pixels to visit from the gradient directions
# find 10 pixels without too much curve
if abs(img[i, j]) > t:
where = round_angle(D[i, j])
try:
if where == 0:
max_length = 1
m = i - 1
while max_length < min_pixel:
if m >= 0 and round_angle(D[m, j]) == 0:
m = m - 1
max_length = max_length + 1
else:
break
if max_length >= min_pixel:
while max_length >= 0:
Z[m, j] = img[m, j]
m = m + 1
max_length = max_length - 1
elif where == 90:
max_length = 1
m = j - 1
while max_length < min_pixel:
if m >= 0 and round_angle(D[i, m]) == 90:
m = m - 1
max_length = max_length + 1
else:
break
if max_length >= min_pixel:
while max_length >= 0:
Z[i, m] = img[i, m]
m = m + 1
max_length = max_length - 1
elif where == 135:
max_length = 1
m = i - 1
n = j - 1
while max_length < min_pixel:
if m >= 0 and n >= 0 and round_angle(D[m,
n]) == 135:
m = m - 1
n = n - 1
max_length = max_length + 1
else:
break
if max_length >= min_pixel:
while max_length >= 0:
Z[m, m] = img[m, n]
m = m + 1
n = n + 1
max_length = max_length - 1
elif where == 45:
max_length = 1
m = i - 1
n = j + 1
while max_length < min_pixel:
if m > 0 and n < N - 1 and round_angle(D[m,
m]) == 45:
m = m - 1
n = n + 1
max_length = max_length + 1
else:
break
if max_length >= min_pixel:
while max_length >= 0:
Z[m, n] = img[m, n]
m = m + 1
n = n - 1
max_length = max_length - 1
except IndexError as e:
""" Todo: Deal with pixels at the image boundaries. """
pass
return Z