pyDistanceBetween2Lines

# Find the minimum distanve between two white lines
# Mike Kerry - Jan 2022 - acclivity2@gmail.com

import cv2
import numpy as np

img = cv2.imread("WhiteLinesCrop.jpg")
dims = img.shape
width = dims[1]
height = dims[0]
print("Width:", width, "  Height:", height)

cv2.imshow("img", img)

array_tr = []   # This array will hold all the coordinates of white pixels in the upper right line
array_bl = []   # This array will hold all the coordinates of white pixels in the lower left line

for y, line in enumerate(img):          # y is line counter (vertical coordinate)
    for x, rgb in enumerate(line):      # x is the horizontal coordinate
        # Is this pixel white?
        if sum(rgb) > 384:              # look for pale pixels  (765 would be pure white, 0 is black)
            # Got a white pixel
            # Is this pixel nearer to the top right, or the bottom left?
            dist_bl = (height - y) ** 2 + x ** 2
            dist_tr = y ** 2 + (width - x) ** 2
            if dist_bl < dist_tr:
                # This pixel is in the lower left line. Add its coordinates to the bottom left array
                array_bl.append((y, x))
                # TESTING ... make bottom left BLUE
                # img[y, x] = (255, 0, 0)
            else:
                # this pixel is in the upper right line
                array_tr.append((y, x))         # Add its coordinates to the top right array

# Find the closest distance between the two lines (i.e. the two arrays)
mindistsq = 999999          # square of the minimum distance
mincoord1 = (0, 0)
mincoord2 = (0, 0)

for coord1 in array_bl:
    for coord2 in array_tr:
        # compute the distance squared, in pixels
        distsq = (coord1[0] - coord2[0]) ** 2 + (coord1[1] - coord2[1]) ** 2
        if distsq < mindistsq:
            mindistsq = distsq
            mincoord1 = coord1      # Remember the coordinates of the closest white points
            mincoord2 = coord2

# Make the closest points red
y, x = mincoord1
for my in range(5):
    for mx in range(5):
        img[y - 2 + my, x - 2 + mx] = (0, 0, 255)       # make pixels red

y, x = mincoord2
for my in range(5):
    for mx in range(5):
        img[y - 2 + my, x - 2 + mx] = (0, 0, 255)

mindist = int(mindistsq ** 0.5)
print("Minimum distance beteween the lines is:", mindist)

cv2.imshow("img", img)
cv2.waitKey(0)


input("Enter:")