migrated from area to sigma

This commit is contained in:
Vighnesh Birodkar
2014-03-11 21:55:09 +05:30
parent a2438b6338
commit 806a52edd5
2 changed files with 72 additions and 78 deletions
+58 -64
View File
@@ -67,9 +67,9 @@ def _prune_blobs(blobs_array, overlap):
Parameters
----------
blobs_array : ndarray
a 2d array with each row representing 3 values, the ``(y,x,sigma)``
where ``(y,x)`` are coordinates of the blob and sigma is the standard
deviation of the Gaussian kernel which detected the blob.
A 2d array with each row representing 3 values, ``(y,x,sigma)``
where ``(y,x)`` are coordinates of the blob and ``sigma`` is the
standard deviation of the Gaussian kernel which detected the blob.
overlap : float
A value between 0 and 1. If the fraction of area overlapping for 2
blobs is greater than `overlap` the smaller blob is eliminated.
@@ -126,8 +126,9 @@ def blob_dog(image, min_sigma=1, max_sigma=50, sigma_ratio=1.6, threshold=2.0,
Returns
-------
A : (n, 3) ndarray
A 2d array with each row containing the Y-Coordinate , the
X-Coordinate and the estimated area of the blob respectively.
A 2d array with each row representing 3 values, ``(y,x,sigma)``
where ``(y,x)`` are coordinates of the blob and ``sigma`` is the
standard deviation of the Gaussian kernel which detected the blob.
References
----------
@@ -137,31 +138,34 @@ def blob_dog(image, min_sigma=1, max_sigma=50, sigma_ratio=1.6, threshold=2.0,
--------
>>> from skimage import data, feature
>>> feature.blob_dog(data.coins(),threshold=.5,max_sigma=40)
array([[ 45, 336, 1608],
[ 52, 155, 1608],
[ 52, 216, 1608],
[ 54, 42, 1608],
[ 54, 276, 628],
[ 58, 100, 628],
[ 120, 272, 1608],
[ 124, 337, 628],
[ 125, 45, 1608],
[ 125, 208, 628],
[ 127, 102, 628],
[ 128, 154, 628],
[ 185, 347, 1608],
[ 193, 213, 1608],
[ 194, 277, 1608],
[ 195, 102, 1608],
[ 196, 43, 628],
[ 198, 155, 628],
[ 260, 46, 1608],
[ 261, 173, 1608],
[ 263, 245, 1608],
[ 263, 302, 1608],
[ 267, 115, 628],
[ 267, 359, 1608]])
array([[ 45, 336, 16],
[ 52, 155, 16],
[ 52, 216, 16],
[ 54, 42, 16],
[ 54, 276, 10],
[ 58, 100, 10],
[120, 272, 16],
[124, 337, 10],
[125, 45, 16],
[125, 208, 10],
[127, 102, 10],
[128, 154, 10],
[185, 347, 16],
[193, 213, 16],
[194, 277, 16],
[195, 102, 16],
[196, 43, 10],
[198, 155, 10],
[260, 46, 16],
[261, 173, 16],
[263, 245, 16],
[263, 302, 16],
[267, 115, 10],
[267, 359, 16]])
Notes
-----
The radius of each blob is approximately :math:`\sqrt{2}sigma`.
"""
if image.ndim != 2:
@@ -192,14 +196,7 @@ def blob_dog(image, min_sigma=1, max_sigma=50, sigma_ratio=1.6, threshold=2.0,
# Convert the last index to its corresponding scale value
local_maxima[:, 2] = sigma_list[local_maxima[:, 2]]
ret_val = _prune_blobs(local_maxima, overlap)
if len(ret_val) > 0:
ret_val[:, 2] = math.pi * \
((ret_val[:, 2] * math.sqrt(2)) ** 2).astype(int)
return ret_val
else:
return []
return _prune_blobs(local_maxima, overlap)
def blob_log(image, min_sigma=1, max_sigma=50, num_sigma=10, threshold=.2,
@@ -238,8 +235,9 @@ def blob_log(image, min_sigma=1, max_sigma=50, num_sigma=10, threshold=.2,
Returns
-------
A : (n, 3) ndarray
A 2d array with each row containing the Y-Coordinate , the
X-Coordinate and the estimated area of the blob respectively.
A 2d array with each row representing 3 values, ``(y,x,sigma)``
where ``(y,x)`` are coordinates of the blob and ``sigma`` is the
standard deviation of the Gaussian kernel which detected the blob.
References
----------
@@ -251,24 +249,27 @@ def blob_log(image, min_sigma=1, max_sigma=50, num_sigma=10, threshold=.2,
>>> img = data.coins()
>>> img = exposure.equalize_hist(img) # improves detection
>>> feature.blob_log(img,threshold = .3)
array([[ 113, 323, 6],
[ 121, 272, 1815],
[ 124, 336, 760],
[ 126, 46, 760],
[ 126, 208, 760],
[ 127, 102, 760],
[ 128, 154, 760],
[ 185, 344, 1815],
[ 194, 213, 1815],
[ 194, 276, 1815],
[ 197, 44, 760],
[ 198, 103, 760],
[ 198, 155, 760],
[ 260, 174, 1815],
[ 263, 244, 1815],
[ 263, 302, 1815],
[ 266, 115, 760]])
array([[113, 323, 1],
[121, 272, 17],
[124, 336, 11],
[126, 46, 11],
[126, 208, 11],
[127, 102, 11],
[128, 154, 11],
[185, 344, 17],
[194, 213, 17],
[194, 276, 17],
[197, 44, 11],
[198, 103, 11],
[198, 155, 11],
[260, 174, 17],
[263, 244, 17],
[263, 302, 17],
[266, 115, 11]])
Notes
-----
The radius of each blob is approximately :math:`\sqrt{2}sigma`.
"""
if image.ndim != 2:
@@ -294,11 +295,4 @@ def blob_log(image, min_sigma=1, max_sigma=50, num_sigma=10, threshold=.2,
# Convert the last index to its corresponding scale value
local_maxima[:, 2] = sigma_list[local_maxima[:, 2]]
ret_val = _prune_blobs(local_maxima, overlap)
if len(ret_val) > 0:
ret_val[:, 2] = math.pi * \
((ret_val[:, 2] * math.sqrt(2)) ** 2).astype(int)
return ret_val
else:
return []
return _prune_blobs(local_maxima, overlap)
+14 -14
View File
@@ -5,6 +5,7 @@ import math
def test_blob_dog():
r2 = math.sqrt(2)
img = np.ones((512, 512))
xs, ys = circle(400, 130, 5)
@@ -17,29 +18,29 @@ def test_blob_dog():
img[xs, ys] = 255
blobs = blob_dog(img, min_sigma=5, max_sigma=50)
area = lambda x: x[2]
radius = lambda x: math.sqrt(x / math.pi)
s = sorted(blobs, key=area)
radius = lambda x: r2*x[2]
s = sorted(blobs, key=radius)
thresh = 5
b = s[0]
assert abs(b[0] - 400) <= thresh
assert abs(b[1] - 130) <= thresh
assert abs(radius(b[2]) - 5) <= thresh
assert abs(radius(b) - 5) <= thresh
b = s[1]
print abs(radius(b))
assert abs(b[0] - 100) <= thresh
assert abs(b[1] - 300) <= thresh
assert abs(radius(b[2]) - 25) <= thresh
assert abs(radius(b) - 25) <= thresh
b = s[2]
assert abs(b[0] - 200) <= thresh
assert abs(b[1] - 350) <= thresh
assert abs(radius(b[2]) - 45) <= thresh
assert abs(radius(b) - 45) <= thresh
def test_blob_log():
r2 = math.sqrt(2)
img = np.ones((512, 512))
xs, ys = circle(400, 130, 5)
@@ -56,27 +57,26 @@ def test_blob_log():
blobs = blob_log(img, min_sigma=5, max_sigma=20, threshold=1)
area = lambda x: x[2]
radius = lambda x: math.sqrt(x / math.pi)
s = sorted(blobs, key=area)
radius = lambda x: r2*x[2]
s = sorted(blobs, key=radius)
thresh = 3
b = s[0]
assert abs(b[0] - 400) <= thresh
assert abs(b[1] - 130) <= thresh
assert abs(radius(b[2]) - 5) <= thresh
assert abs(radius(b) - 5) <= thresh
b = s[1]
assert abs(b[0] - 160) <= thresh
assert abs(b[1] - 50) <= thresh
assert abs(radius(b[2]) - 15) <= thresh
assert abs(radius(b) - 15) <= thresh
b = s[2]
assert abs(b[0] - 100) <= thresh
assert abs(b[1] - 300) <= thresh
assert abs(radius(b[2]) - 25) <= thresh
assert abs(radius(b) - 25) <= thresh
b = s[3]
assert abs(b[0] - 200) <= thresh
assert abs(b[1] - 350) <= thresh
assert abs(radius(b[2]) - 30) <= thresh
assert abs(radius(b) - 30) <= thresh