如何获得图像的 4 x 4 边界框及其相应的坐标？

Question

I am trying get 4 by 4 bounding boxes of an image. Like this bounding box

Bounding Boxes

Can someone please help me how to get those bounding boxes and their coordinates?

Answer 1

From my understanding, you are trying to visually split the input image to 4 squares. In this case all you need is to draw two lines: one horizontal, one vertical. see Drawing Functions in OpenCV documentation . A quick example:

import cv2

height, width = input_image.shape[:2]

# for horizontal line
horizontal_left = (0, int(height / 2))
horizontal_right = (int(width), int(height / 2))

cv2.line(input_image, horizontal_left, horizontal_right, (0, 255, 0), 1)

# for vertical
vertical_top = (int(width / 2), 0)
vertical_bottom = (int(width / 2), int(height))

cv2.line(input_image, vertical_top, vertical_bottom, (0, 255, 0), 1)

Answer 2

To create and rectangle use this piece of code.

import cv2

cv2.rectangle(img, (x1, y1), (x2, y2), (255,0,0), 2)


x1,y1 ------
|          |
|          |
|          |
--------x2,y2

And if you want to draw your own ROI use this piece of code.

import cv2
import numpy as np

if __name__ == '__main__' :

    # Read image
    im = cv2.imread("image.jpg")

    # Select ROI
    r = cv2.selectROI(im)

    # Crop image
    imCrop = im[int(r[1]):int(r[1]+r[3]), int(r[0]):int(r[0]+r[2])]

    # Display cropped image
    cv2.imshow("Image", imCrop)
    cv2.waitKey(0)