plot 这个白色像素有正确的方法吗？

Question

iam a beginner at python and image processing etc. I want to plot this white pixel. as i know the pixel color identifier for black is 0 and for white is 255. here's the image that i want to plot:

The Image

i try to print out the image ndarray with these following command:

#importing module
import cv2
import numpy as np
import matplotlib.pyplot as plt
import sys

#load image
img = cv2.imread('thin.png')

#image to nd.array
arr0 = np.array(img)

#finding white pixel
arr1 = np.where(arr0 == 255)


#indexing tuple, the printout arr1 is tuple with dtype=int64
tuple1 = arr1[0]
tuple2 = arr1[1]
tuple3 = arr1[2]

#defining x and y axis
x = np.array(tuple1)
y = np.array(tuple2)
z = np.array(tuple3)

plot = plt.plot(x,y)
plt.show()

this is what i get..

output image

i think it's very noisy but i dont have a clue. Thank you very much for help

Answer 1

I think there is some confusion in the dimensions of you array arr0 . I think you should look at the indices of the white pixels:

import cv2
import numpy as np
import matplotlib.pyplot as plt

#load image
img = cv2.imread('thin.png')

#image to nd.array
arr0 = np.array(img)

height, width, _ = arr0.shape

x = range(width)
y = [height - np.argwhere(arr0[:, i, 0]==255).mean() for i in x]    # "height -" to reverse the y-axis

plt.plot(x,y)
plt.show()

Note: taking the mean because a vertical line can have more than one white pixel (also some won't have any, see picture below)

Output: