cv2 imshow command doesn t work properly in opencv-python

Question

I m using opencv 2 4 2  python 2 7 The following simple code created a window of the correct name  but its content is just blank and doesn t show the image   import cv2 img cv2 imread  C  Python27 03323 HD jpg   cv2 imshow  ImageWindow  img    does anyone knows about this issue

User · Answer

If you choose to use  cv2 waitKey 0    be sure that you have written  cv2 waitKey 0   instead of  cv2 waitkey 0    because that lowercase  k  might freeze your program too

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Method 1  The following code worked for me  Just adding the destroyAllWindows   didn t close the window  Adding another cv2 waitKey 1  at the end did the job  im   cv2 imread  quot   input jpg quot   cv2 imshow  quot image quot   im  cv2 waitKey 0  cv2 destroyAllWindows   cv2 waitKey 1   credit   https   stackoverflow com a 50091712 8109630 Note for beginners   This will open the image in a separate window  instead of displaying inline on the notebook  That is why we have to use the destroyAllWindows   to close it later  So if you don t see a separate window pop up  check if it is behind your current window  After you view the image press a key to close the popped up window   Method 2  If you want to display on the Jupyter notebook  from matplotlib import pyplot as plt import cv2  im   cv2 imread  quot   input jpg quot   color   cv2 cvtColor im  cv2 COLOR BGR2RGB  plt imshow color  plt title  Image   plt show

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error   -215  size width 0  amp  amp  size height 0 in function imshow   This error is produced because the image is not found  So it s not an error of imshow function

User · Answer

imshow   only works with waitKey     import cv2 img   cv2 imread  C  Python27 03323 HD jpg   cv2 imshow  ImageWindow   img  cv2 waitKey      The whole message-loop necessary for updating the window is hidden in there

User · Answer

I faced the same issue  I tried to read an image from IDLE and tried to display it using cv2 imshow    but the display window freezes and shows pythonw exe is not responding when trying to close the window   The post below gives a possible explanation for why this is happening  pythonw exe is not responding   Basically  don t do this from IDLE  Write a script and run it from the shell or the script directly if in windows  by naming it with a  pyw extension and double clicking it  There is apparently a conflict between IDLE s own event loop and the ones from GUI toolkits    When I used imshow   in a script and execute it rather than running it directly over IDLE  it worked

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This is how I solved it  import cv2 from matplotlib import pyplot      img   cv2 imread  path   pyplot imshow img  pyplot show

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If you are running inside a Python console  do this   img   cv2 imread  yourimage jpg    cv2 imshow  img   img   cv2 waitKey 0   cv2 destroyAllWindows     Then if you press Enter on the image  it will successfully close the image and you can proceed running other commands

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I also had a -215 error  I thought imshow was the issue  but when I changed imread to read in a non-existent file I got no error there  So I put the image file in the working folder and added cv2 waitKey 0  and it worked

User · Answer

You must use cv2 waitKey 0  after cv2 imshow  window  img   Only then will it work   import cv2 img cv2 imread  C  Python27 03323 HD jpg   cv2 imshow  Window  img  cv2 waitKey 0

User · Answer

You ve got all the necessary pieces somewhere in this thread   if cv2 waitKey    cv2 destroyAllWindows     works fine for me in IDLE

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If you have not made this working  you better put  import cv2 img cv2 imread  C  Python27 03323 HD jpg   cv2 imshow  Window  img  cv2 waitKey 0    into one file and run it

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Doesn t need any additional methods after waitKey 0   reply for above code   import cv2 img cv2 imread  C  Python27 03323 HD jpg   cv2 imshow  ImageWindow  img  cv2 waitKey 0    Window appears -  Click on the Window  amp  Click on Enter  Window will close

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For me waitKey   with number greater than 0 worked      cv2 waitKey 1

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I found the answer that worked for me here  http   txt arboreus com 2012 07 11 highgui-opencv-window-from-ipython html     If you run an interactive ipython session  and want to use highgui   windows  do cv2 startWindowThread   first       In detail  HighGUI is a simplified interface to display images and   video from OpenCV code  It should be as easy as    import cv2 img   cv2 imread  image jpg   cv2 startWindowThread   cv2 namedWindow  preview   cv2 imshow  preview   img

User · Answer

add cv2 waitKey 0  in the end

User · Answer

I had the same 215 error  which I was able to overcome by giving the full path to the image  as in  C  Folder1 Folder2 filename ext

[python] cv2.imshow command doesn't work properly in opencv-python

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