Numpy Array：在一行中的計數值（來自圖像）

Question

我在NumPy中有幾張黑色（= 1）和白色（= 0）圖像。我想計算在所有2D方向上直線的次數。

只要不再連續，我想停止計數。我需要從線的兩邊數。這個想法是能夠從一側提取直線距離另一側直線多長時間。

請看下面的MWE，我希望能更好地解釋我的問題。

import numpy as np 
import matplotlib.pylab as plt 
from matplotlib import gridspec 

background = np.zeros((60,60)) 

one = background.copy() # straight line 
one[10,5:30:1] = 1 
# Here I'd like to count 25 from both directions 

two = background.copy() # diagonal line, this stands for all angles the diagonal line could have, not just 45degrees! 
two[[range(10,35)],[range(5,30)]] = 1 
# Here I'd like to count 25 from both directions 

three = background.copy() # line with right angle 
three[10,5:15:1] = 1 
three[10:25:1,15] = 1 
# Here I'd like to count 10 from one end and 15 from the other 

gs = gridspec.GridSpec(2,2) 
fig = plt.figure() 
line = fig.add_subplot(gs[0,0]) 
diag = fig.add_subplot(gs[0,1]) 
angle = fig.add_subplot(gs[1,0]) 
line.imshow(one), line.set_title('Count 25 from both sides') 
diag.imshow(two), diag.set_title('Count 25 from both sides') 
angle.imshow(three), angle.set_title('Count 10 from one side and 15 from the other') 

我的問題是，我甚至不知道google一下。

非常感謝！

Answer 1

感謝Gareth（請參閱我的問題的評論）我能夠弄清楚這一點。霍夫轉換是我正在尋找的解決方案。

Scipy有一個功能來做到這一點。該文檔可以找到here和一個很好的演示和解釋可以發現here。

我在上面的問題中實現瞭解決方案。我還添加了一個例子，其中一個像素不在一條直線上，但「足夠直」。這可能受probabilistic_hough_line函數的參數影響。

import numpy as np 
import matplotlib.pylab as plt 
from matplotlib import gridspec 
from skimage.transform import probabilistic_hough_line 

background = np.zeros((60,60)) 

one = background.copy() # straight line 
one[10,5:30:1] = 1 
# Here I'd like to count 25 from both directions 

two = background.copy() # diagonal line, this stands for all angles the diagonal line could have, not just 45degrees! 
two[[range(10,35)],[range(5,30)]] = 1 
# Here I'd like to count 25 from both directions 

three = background.copy() # line with right angle 
three[10,5:15:1] = 1 
three[10:25:1,15] = 1 
# Here I'd like to count 10 from one end and 15 from the other 

four = background.copy() # line with one value out of place and a right angle 
four[10,5:8:1] = 1 
four[11,8] = 1 
four[10,9:15] = 1 
four[10:25:1,15] = 1 
# Here I'd like to count 10 from one side and 15 from the other side 

gs = gridspec.GridSpec(2,2) 
fig = plt.figure() 
line_plt = fig.add_subplot(gs[0,0]) 
diag = fig.add_subplot(gs[0,1]) 
angle = fig.add_subplot(gs[1,0]) 
angle_dirty = fig.add_subplot(gs[1,1]) 
line_plt.imshow(one), line_plt.set_title('Count 25 from both sides') 
diag.imshow(two), diag.set_title('Count 25 from both sides') 
angle.imshow(three), angle.set_title('Count 10 from one side and 15 from the other') 
angle_dirty.imshow(four), angle_dirty.set_title('Count 10 from one side and 15 from the other') 

# This function returns the List of lines identified, lines in format ((x0, y0), (x1, y0)), indicating line start and end. 
lines_one = probabilistic_hough_line(one, threshold=10, line_length=5, line_gap=3) 
# Now to the plotting on top of the original image 
for line in lines_one: 
    p0, p1 = line 
    line_plt.plot((p0[0], p1[0]), (p0[1], p1[1])) 

lines_two = probabilistic_hough_line(two, threshold=10, line_length = 5, line_gap = 3) 
for line in lines_two: 
    p0, p1 = line 
    diag.plot((p0[0], p1[0]), (p0[1], p1[1])) 

lines_three = probabilistic_hough_line(three, threshold=10, line_length = 5, line_gap = 3) 
for line in lines_three: 
    p0, p1 = line 
    angle.plot((p0[0], p1[0]), (p0[1], p1[1])) 

lines_four = probabilistic_hough_line(four, threshold=10, line_length = 5, line_gap = 3) 
for line in lines_four: 
    p0, p1 = line 
    angle_dirty.plot((p0[0], p1[0]), (p0[1], p1[1]))