CODEWITHSUNDEEP
pythonnumpyopencvslice
ytu
ytu

Reputation: 1850

Crop an image in multiple rectangles and combine them into one in Python OpenCV

I've been referred to How to crop an image in OpenCV using Python, but my question has a little difference.

This can be a numpy-slicing problem. I know I can do:

import cv2
img = cv2.imread("test_image.jpg")
crop_img = img[y:y+h, x:x+w]

But what if I need two rectangles with the same y range but non-consecutive x ranges of the original picture? I've tried:

crop_img = img[y:y+h, [x1:x1+w1, x2:x2+w2]]

What I expected was a rectangular having its height from y to y+h, and its width from x1 to x1+w1 plus x2 to x2+w2, where x1+w1 doesn't have to be equal to x2. Nevertheless I get a SyntaxError with "invalid syntax". Is there a way to correctly achieve my goal?

Upvotes: 0

Views: 3483

Answers (1)

eyllanesc
eyllanesc

Reputation: 243993

You have to extract each part and then concatenate with the help of the concatenate function of numpy.

import numpy as np

v1 = img[y:y+h, x1:x1+w1]
v2 = img[y:y+h, x2:x2+w2]

v = np.concatenate((v1, v2), axis=1)

Or:

indexes = ((x1, w1), (x2, w2))
v = np.concatenate([img[y: y+h , v1: v1+v2] for v1,v2 in indexes], axis=1)

Another way:

Creating indexes as lists

v = img[y:y+h, list(range(x1, x1+w1)) + list(range(x2, x2 + w2))]

Upvotes: 2

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