如何使用OpenCV (Python)在下图中获得所需的投资回报率？

import cv2
import numpy as np

image = cv2.imread('image.jpg')
cv2.imshow('Image', image)
cv2.waitKey(0)
cv2.destroyAllWindows()

resized_image = cv2.resize(image, (800, 600))
gray_image = cv2.cvtColor(resized_image, cv2.COLOR_BGR2GRAY)
blurred_image = cv2.GaussianBlur(gray_image, (5, 5), 0)

edges = cv2.Canny(blurred_image, 50, 150)

lines = cv2.HoughLinesP(edges, 1, np.pi/180, threshold=100, minLineLength=100, maxLineGap=10)

total_length = 0
for line in lines:
    x1, y1, x2, y2 = line[0]
    length = np.sqrt((x2 - x1)**2 + (y2 - y1)**2)
    total_length += length

investment = 1000  # 假设投资金额为1000美元
roi = total_length / investment
print("投资回报率：", roi)