No namedWindow function automatically perform a former imshow function, but this function to create a window of default parameters for the cv2.WINDOW_AUTOSIZE
Window size will automatically adapt the displayed image, and can not change the size of the window
cv2.namedWindow("demo" , cv2.WINDOW_NORMAL) cv2.imshow("demo" , lena)
This can adjust the size of the time window generation
Different window function may be obtained by varying the parameters
| Window size can be changed | cv2.WINDOW_NORMAL |
| You can not change the window size | cv2.WINDOW_AUTOSIZE |
| Adaptive window size than the column | cv2.WINDOW_FREERATIO |
| Window size remains proportion | cv2.WINDOW_KEEPRATIO |
| Display color becomes dark | cv2.WINDOW_GUI_EXPANDED |