How to resize window in opencv2 python

I am using opencv 2 with a webcam. I can get the video stream and process it, but I can’t seem to figure out a way to resize the display window. I have some video images stacked horizontally, but the image dimension is very small that it’s difficult to see things.

My code is pretty simple, and along the lines of this:

cv2.namedWindow("main")

....

result = np.hstack((res2, foreground))
result = np.hstack((ff, result))

cv2.imshow("main", result)
cv2.waitKey(20)

The opencv documentation states:

namedWindow
flags – Flags of the window. Currently the only supported flag is CV_WINDOW_AUTOSIZE . If this is set, the window size is automatically adjusted to fit the displayed image (see imshow() ), and you cannot change the window size manually.

But qt backends apparently have extra flags. I don’t have a qt backend. Is there a way for me to increase the size of the images so that I can see them?

Answer

Yes, unfortunately you can’t manually resize a nameWindow window without Qt backend. Your options:

use cv2.resize function to resize the image to desired size prior to displaying the image
install OpenCV with Qt backend support and use cv2.namedWindow("main", CV_WINDOW_NORMAL)

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Answer