I am trying to get all the lines in this image:
This is the code that I'm using:
threshold = 30
minLineLength =10
maxLineGap = 10
lines = cv2.HoughLinesP(img,1,np.pi/360, threshold, minLineLength, maxLineGap)
The problem is that I'm getting too many lines (~300):
But if I increase the threshold value it starts to miss some lines:
Is there any way of reducing the number of lines while keeping line-detection accurate?
Thanks in advance!
It works (mostly) fine for me in Python/OpenCV. Adjust your HoughP line arguments as appropriate.
I think you need to threshold your image first. And perhaps thin the white lines.
Input:
import cv2
import numpy as np
# read image as color not grayscale
img = cv2.imread("lines.png", cv2.IMREAD_COLOR)
# convert img to grayscale
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
# do threshold
thresh = cv2.threshold(gray, 30, 255, cv2.THRESH_BINARY)[1]
# get hough line segments
threshold = 30
minLineLength =10
maxLineGap = 10
lines = cv2.HoughLinesP(thresh, 1, np.pi/360, threshold, minLineLength, maxLineGap)
# draw lines
results = img.copy()
for [line] in lines:
print(line)
x1 = line[0]
y1 = line[1]
x2 = line[2]
y2 = line[3]
cv2.line(results, (x1,y1), (x2,y2), (0,0,255), 1)
# show lines
cv2.imshow("lines", results)
cv2.waitKey(0)
# write results
cv2.imwrite("lines_hough.png",results)
Resulting Hough lines in red:
You get a lot of parallel very close lines that you may want to merge somehow or thin out the list.