OpenCV src empty in function cvtColor error

Question

I am trying to do a basic colour conversion in python however I can t seem to get past the below error  I have re-installed python  opencv and tried on both python 3 4 3  latest  and python 2 7  which is on my Mac    I installed opencv using python s package manager opencv-python    Here is the code that fails   frame   cv2 imread  frames frame d tiff    count  frame HSV  cv2 cvtColor frame cv2 COLOR RGB2HSV    This is the error message   cv2 error  OpenCV 3 4 3   Users travis build skvark opencv-python opencv modules imgproc src color cpp 181  error   -215 Assertion failed    src empty   in function  cvtColor

User · Answer

I had the same problem and it turned out that my image names included special characters (e.g. château.jpg), which could not bet handled by cv2.imread. My solution was to make a temporary copy of the file, renaming it e.g. temp.jpg, which could be loaded by cv2.imread without any problems.

Note: I did not check the performance of shutil.copy2 vice versa other options. So probably there is a better/faster solution to make a temporary copy.

import shutil, sys, os, dlib, glob, cv2

for f in glob.glob(os.path.join(myfolder_path, "*.jpg")):
    shutil.copy2(f, myfolder_path + 'temp.jpg')
    img = cv2.imread(myfolder_path + 'temp.jpg')
    img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
    os.remove(myfolder_path + 'temp.jpg')

If there are only few files with special characters, renaming can also be done as an exeption, e.g.

for f in glob.glob(os.path.join(myfolder_path, "*.jpg")):
    try:
        img = cv2.imread(f)
        img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
    except:
        shutil.copy2(f, myfolder_path + 'temp.jpg')
        img = cv2.imread(myfolder_path + 'temp.jpg')
        img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
        os.remove(myfolder_path + 'temp.jpg')

User · Answer

I ve been in same situation as well  and My case was because of the Korean letter in the path     After I remove Korean letters from the folder name  it works   OR put     - - coding utf-8 - -     except     at the edge   or something like that in the first line to make python understand Korean or your language or etc  then it will work even if there is some Koreans in the path in my case   So the things is  it seems like there is something about path or the letter  People who answered are saying similar things  Hope you guys solve it

User · Answer

If anyone is experiencing this same problem when reading a frame from a webcam  with code similar to  quot frame   cv2 VideoCapture 0  quot   and work in Jupyter Notebook  you may try   ensure previously tried code is not running already and restart Jupyter Notebook kernel  SEPARATE code  quot frame   cv2 VideoCapture 0  quot  in separate cell on place where it is  previous code put in cell above  code under put to cell down   then run all the code above cell where is  quot frame   cv2 VideoCapture 0  quot   then try run next cell with its only code  quot frame   cv2 VideoCapture 0  quot  - AND - till you will continue in executing other cells - ENSURE - that ASTERIX on the left side of this particular cell DISAPEAR and command order number appear instead - only then continue  now you can try execute the rest of your code as your camera input should not be empty anymore  -   After end  ensure you close all your program and restart kernel to prepare it for another run

User · Answer

Your code can t find the figure or the name of your figure named the by error message  Solution   import cv2 import numpy as np  import matplotlib pyplot as plt  img cv2 imread     jpg   solution img cv2 imread  haha jpg   print img

User · Answer

In my case  the image was incorrectly named  Check if the image exists and try  import numpy as np import cv2  img   cv2 imread  image png   0  cv2 imshow  image   img

User · Answer

If the path is correct and the name of the image is OK  but you are still getting the error  use   from skimage import io  img   io imread file path    instead of   cv2 imread file path       The function imread loads an image from the specified file and returns   it  If the image cannot be read  because of missing file  improper permissions  unsupported or invalid format   the function returns an empty matrix   Mat  data  NULL

User · Answer

I kept getting this error too   Traceback  most recent call last     File  face detector py   line 6  in  lt module gt      gray img cv2 cvtColor img  cv2 COLOR BGR2GRAY  cv2 error  OpenCV 4 1 0  C  projects opencv-python opencv modules imgproc src color cpp 182  error   -215 Assertion failed    src empty   in function  cv  cvtColor   My cv2 cvtColor      was working fine with  photo jpg but not with  news jpg  For me  I finally realized that when working on Windows with python  those escape characters will get you every time   So my  bad  photo was being escaped because of the file name beginning with  n   Python took the  n as an escape character and OpenCV couldn t find the file   Solution  Preface file names in Windows python with r           as in   cv2 imread r   images news jpg

User · Answer

Check whether its the jpg  png  bmp file that you are providing and write the extension accordingly

User · Answer

The solution os to ad      before the name of image before reading it

User · Answer

Most probably there is an error in loading the image  try checking directory again  Print the image to confirm if it actually loaded or not

User · Answer

must please see guys that the error is in the cv2 imread    Give the right path of the image  and firstly  see if your system loads the image or not  this can be checked first by simple load of image using cv2 imread    after that  see this code for the face detection  import numpy as np import cv2  cascPath     Users mayurgupta opt anaconda3 lib python3 7 site-   packages cv2 data haarcascade frontalface default xml   eyePath     Users mayurgupta opt anaconda3 lib python3 7 site-packages cv2 data haarcascade eye xml   smilePath     Users mayurgupta opt anaconda3 lib python3 7 site-packages cv2 data haarcascade smile xml   face cascade   cv2 CascadeClassifier cascPath  eye cascade   cv2 CascadeClassifier eyePath  smile cascade   cv2 CascadeClassifier smilePath   img   cv2 imread  WhatsApp Image 2020-04-04 at 8 43 18 PM jpeg   gray   cv2 cvtColor img  cv2 COLOR BGR2GRAY   faces   face cascade detectMultiScale gray  1 3  5  for  x y w h  in faces      img   cv2 rectangle img  x y   x w y h   255 0 0  2      roi gray   gray y y h  x x w      roi color   img y y h  x x w      eyes   eye cascade detectMultiScale roi gray      for  ex ey ew eh  in eyes          cv2 rectangle roi color  ex ey   ex ew ey eh   0 255 0  2   cv2 imshow  img  img  cv2 waitKey 0  cv2 destroyAllWindows     Here  cascPath  eyePath  smilePath should have the right actual path that s picked up from lib python3 7 site-packages cv2 data here this path should be to picked up the haarcascade files

User · Answer

If anyone is experiencing this same problem when reading a frame from a webcam   Verify if your webcam is being used on another task and close it  This wil solve the problem    I spent some time with this error when I realized my camera was online in a google hangouts group  Also  Make sure your webcam drivers are up to date

User · Answer

In my case it was a permission issue  I had to    chmod a wrx the image     then it worked

User · Answer

Another thing which might be causing this is a  weird  symbol in your file and directory names  All umlaut          and other         etc  characters should be removed from the file and folder names  I ve had this same issue sometimes because of these characters

User · Answer

This error happened because the image didn t load properly   So you have problem with the previous line cv2 imread my suggestion is     check if the images exist in the path you give check the count variable if he have valid number

[python] OpenCV !_src.empty() in function 'cvtColor' error

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