尝试在 openCV Python 中的图像中捕获形状

Question

i have the image shown below and i am attempting to just capture the Squares and place a green line around them any help or direction would be great.

import numpy as np
import cv2

img = cv2.imread('beef.png')
imgGry = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

ret , thrash = cv2.threshold(imgGry, 240 , 255, cv2.CHAIN_APPROX_NONE)
contours , hierarchy = cv2.findContours(thrash, cv2.RETR_TREE, cv2.CHAIN_APPROX_NONE)

for contour in contours:
approx = cv2.approxPolyDP(contour, 0.01* cv2.arcLength(contour, True), True)
cv2.drawContours(img, [approx], 0, (0, 0, 0), 5)
x = approx.ravel()[0]
y = approx.ravel()[1] - 5
x, y , w, h = cv2.boundingRect(approx)
aspectRatio = float(w)/h
print(aspectRatio)

if aspectRatio >= 0.95 and aspectRatio < 1.05:
cv2.putText(img, "square", (x, y), cv2.FONT_HERSHEY_COMPLEX, 0.5, (0, 0, 0))

else:
cv2.putText(img, "rectangle", (x, y), cv2.FONT_HERSHEY_COMPLEX, 0.5, (0, 0, 0))

cv2.imshow('shapes', img)
cv2.waitKey(0)
cv2.destroyAllWindows()

Answer 1

I don't know exactly what your problem is (are the contours wrong? Nothing is being drawn on the image? etc) but here are some guesses.

To draw lines around the contours, it looks like you are currently using white (0,0,0) to outline it. -1 is to draw all contours to see if you are getting any results.

Also some cv2 functions are destructive so I never use img when I am creating the output image. I would imShow and drawContours on a copy of the original img.

cv2.drawContours(img, contours, -1, GREEN, 5)