Image
I am trying to find the position of the rectangle in the image. Considering the top part of the image as reference, how can I find the position of the rectangle? I want the coordinates of the four vertices.
I have tried findContours and bounded rectangle method but have not been able to get the coordinates. Help would be appreciated.
Just get contour and then find bounding rectangle. Check this tutorial from official documentation.
import cv2
img = cv2.imread('image.jpg')
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
ret, thresh = cv2.threshold(gray, 80, 255, cv2.THRESH_BINARY)
_, contours, _ = cv2.findContours(thresh,
cv2.RETR_TREE,
cv2.CHAIN_APPROX_NONE)
x1, y1, w, h = cv2.boundingRect(contours[0])
x2, y2 = x1 + w, y1 + h
print((x1, y1), (x2, y2))
cv2.rectangle(img, (x1, y1), (x2, y2), (0, 255, 0), 2)
cv2.imwrite('res.jpg', img)
Coordinates of upper-left and lower-right points of rectangle ((x1, y1), (x2, y2)):
(369, 0) (901, 433)
Result:
just adapting the cv2 tutorial, you can find the largest contour and then obtain its bounding rectangle.
img = cv2.imread('/home/kvnp/Desktop/v02J6.jpg',0) #read in the image with correct dtype
_,thresh = cv2.threshold(img,200,255,0) # threshold the image
_,contours,_ = cv2.findContours(thresh, 1, 2) # find the contours
cnt = sorted(contours, key = lambda c: -len(c))[0] # order from largest to smallest and select the largest
x,y,w,h = cv2.boundingRect(cnt) # make bounding rectangle around the largest contour
corners = np.array([[x,y],[x+w,y],[x+w,y+h],[x,y+h]]) # make array of corners sorted clockwise
This image I get
>>> corners
array([[371, 1],
[900, 1],
[900, 430],
[371, 430]])
