pyFindCoordsOfWhiteSpots

# Script to locate 3 white spots on a black background, which mark the points of a triangle
# and determine the row and column coordinates of these spots

# Mike Kerry Jan 2022

import cv2
import numpy as np

# Function to compute the distance (in pixels) between a pair of y, x coordinates
def distance(yx1, yx2):
    dsq = (yx1[0] - yx2[0]) ** 2 + (yx1[1] - yx2[1]) ** 2
    return round(dsq ** 0.5)

img = cv2.imread("Triangle.jpg")        # Read the image into a Numpy array
height, width, a = img.shape            # Get the number of rows and columns

spotcoords = []
for row, rowdata in enumerate(img):
    for col, bgr in enumerate(rowdata):
        bright = sum(bgr)               # Compute whiteness by summing Blue + Green + Red
        if bright > 700:
            # See if this pixel is close to an already found spot. If not, it's a new spot
            for tup in spotcoords:
                d = distance(tup, (row, col))
                if d < 20:              # Ignore white pixels close to known points
                    break
            else:
                spotcoords.append((row, col))       # Append y,x tuple to our coordinates list

print(spotcoords)            # Output:  [(194, 467), (317, 170), (354, 290)]
# Now we know the y,x coordinates of the 3 spots

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