spectrum

import matplotlib.pyplot as plt
import matplotlib.image as mpimg
from PIL import Image
import cv2
import numpy as np

points = []

def onMouse(event, x, y, flags,param):
    if event == cv2.EVENT_LBUTTONDBLCLK:
        print(x, y)
        points.append((x, y))
        if len(points) == 1:
            print("click on the red border")


print("enter picture's name")
while True:
    try:
        fname = input()
        img = cv2.imread(fname, 1)
        img = cv2.resize(img, (0,0), fx=0.5, fy=0.5)

        arr = img
        break
    except Exception:
        print("couldn't find image")

print("click on the violet border")
cv2.namedWindow('image')
cv2.setMouseCallback('image', onMouse)

while len(points) < 2:
    cv2.imshow('image',img)
    k = cv2.waitKey(20) & 0xFF
    if k == 27:
        break



print(arr.shape)
line = []

print(points)
for i in range(points[0][1], points[1][1]):
    pixel = arr[i][points[0][0]]
    #print(pixel)
    now = 0
    for j in pixel:
        now += j

    line.append(now)
line = line[::-1]
plot = plt.plot(line)
plt.show()