如何使用opencv在python中计算不对称形状区域

Question

我需要计算如下图所示的非对称形状的面积

此代码读取图像并将其转换为灰色并找到形状 我需要找出不对称形状的区域

import numpy as np
import cv2

# load the image, convert it to grayscale, and blur it slightly
image = cv2.imread("download.jpg")
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
gray = cv2.GaussianBlur(gray, (7, 7), 0)


# find contours in the edge map
cnts = cv2.findContours(gray.copy(), cv2.RETR_EXTERNAL,
    cv2.CHAIN_APPROX_SIMPLE)

cv2.drawContours(image,cnts, 0, (255, 0, 0), 8)
cv2.imshow("Image", image)
cv2.waitKey(0)

Answer 1

我已经测试了您的代码，发现没有找到形状的轮廓。这是因为您以灰色图像制作了cv2.findContours。该图像应为二进制图像，因此我使用了cv2.threshold。然后可以使用cv2.contourArea计算面积。

下面是代码和结果。

import numpy as np
import cv2

image = cv2.imread("1.jpg")
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
gray = cv2.GaussianBlur(gray, (7, 7), 0)

_,thresh = cv2.threshold(gray,128,255,cv2.THRESH_BINARY_INV)

im, cnts, hier = cv2.findContours(thresh.copy(), cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)

for cnt in cnts:
    cv2.drawContours(image,cnts, -1, (0, 0, 255), 1)
    print(cv2.contourArea(cnt))


cv2.imshow("thresh", thresh)
cv2.imshow("Image", image)
cv2.waitKey(0)

>> 8656.0
>> 3824.5