我正在尝试使用霍夫线对图像进行过滤,但有些功能不起作用。
我创建了以下子例程,该子例程未经文档的修改即被复制粘贴:
def FilterLines(img):
lines = cv2.HoughLines(img,1,np.pi/180,200)
blank_image = np.zeros((img.shape[0], img.shape[1]), np.uint8)
if (lines is None):
return blank_image
for rho,theta in lines[0]:
a = np.cos(theta)
b = np.sin(theta)
x0 = a*rho
y0 = b*rho
x1 = int(x0 + 1000*(-b))
y1 = int(y0 + 1000*(a))
x2 = int(x0 - 1000*(-b))
y2 = int(y0 - 1000*(a))
cv2.line(blank_image,(x1,y1),(x2,y2),255,1)
return blank_image
所以它在底部检测到了几行,什么也没发现。
为什么函数不能在如此简单的图像中检测到线条?
答案 0 :(得分:1)
问题是此行for rho,theta in lines[0]:
。您仅使用一行,第一行line[0]
。
您需要像这样更改for循环:
for x in range(0, len(lines)):
for rho, theta in lines[x]:
然后,整个代码如下所示(在我将它们放入测试中之后,注释了额外的调试语句):
import cv2
import os
import numpy as np
#path = os.path("D:\")
img = cv2.imread("D:\\oV1PG.png")
#cv2.imshow('image',img)
#cv2.waitKey(0)
img = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
#print(img)
'''height, width, channel = img.shape[:3]
size = img.size
print(height, width, channel, size)'''
if img is not None:
lines = cv2.HoughLines(img, 1, np.pi / 180, 100)
blank_image = np.zeros((img.shape[0], img.shape[1]), np.uint8)
for x in range(0, len(lines)):
for rho, theta in lines[x]:
a = np.cos(theta)
b = np.sin(theta)
x0 = a * rho
y0 = b * rho
x1 = int(x0 + 1000 * (-b))
y1 = int(y0 + 1000 * (a))
x2 = int(x0 - 1000 * (-b))
y2 = int(y0 - 1000 * (a))
cv2.line(blank_image, (x1, y1), (x2, y2), 255, 1)
print(x1, y1, x2, y2)
print("\n")
cv2.imshow("out", blank_image)
cv2.waitKey(0)
else:
print("empty img. Cannot read file")
这是我的PC上输出的外观:
答案 1 :(得分:0)
使用此代码。 openCV版本存在冲突,因此我们无法以这种方式执行上述操作。
import cv2
import numpy as np
img = cv2.imread('image.jpg')
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
edges = cv2.Canny(gray,50,150,apertureSize = 3)
lines = cv2.HoughLines(edges,1,np.pi/180,200)
for line in lines:
rho = line[0][0]
theta = line[0][1]
a = np.cos(theta)
b = np.sin(theta)
x0 = a*rho
y0 = b*rho
x1 = int(x0 + 1000*(-b))
y1 = int(y0 + 1000*(a))
x2 = int(x0 - 1000*(-b))
y2 = int(y0 - 1000*(a))
cv2.line(img,(x1,y1),(x2,y2),(0,0,255),2)
cv2.imwrite('houghlines3.jpg',img)