OpenCv cv.Canny函数总是报错

Question

import cv2 as cv
import numpy as np

def line_detect(image):

    edges = cv.Canny(image, 50, 200, apertureSize=3)
    print("edges", edges)
    lines = cv.HoughLines(edges, 1, np.pi/180, 150)
    for line in lines:
        rho, theta = line[0]
        a = np.cos(theta)
        b = np.sin(theta)
        x0 = a * rho
        y0 = b * rho
        x1 = int(x0 + 1000 * (-b))
        y1 = int(y0 + 1000 * (a))
        x2 = int(x0 - 1000 * (-b))
        y2 = int(y0 - 1000 * (a))
        cv.line(image, (x1, y1), (x2, y2), (0, 0, 255), 2)
    cv.imshow("image_lines", image)

print("Hello")
src = cv.imread("F:/2.png")

src1 = np.array(src)

src1[..., 0] = src1[..., 0] * 0.299
src1[..., 1] = src1[..., 1] * 0.587
src1[..., 2] = src1[..., 2] * 0.114

src1 = np.sum(src1, axis=-1)

line_detect(src1)

cv.waitKey(0)

Hello
Traceback (most recent call last):
File "E:/PycharmProjects/learnPython/venv/test.py", line 33, in
line_detect(src1)
File "E:/PycharmProjects/learnPython/venv/test.py", line 6, in line_detect
edges = cv.Canny(image, 50, 200, apertureSize=3)
cv2.error: OpenCV(4.5.2) :-1: error: (-5:Bad argument) in function 'Canny'

Overload resolution failed:

• image data type = 8 is not supported
• Expected Ptrcv::UMat for argument 'image'
• Required argument 'threshold2' (pos 4) not found
• Required argument 'threshold2' (pos 4) not found

![img](

Answer 1

1.image要求是CV_8UC1或者CV_8UC3，你这个numpy操作之后变成浮点数了，canny不支持的。
2.改成edges = cv.Canny(image, threshold1=50, threshold2=200, apertureSize=3)