Warning: can't open/read file: check file path/integrity

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Borislav Hadzhiev

Last updated: Apr 11, 2024
4 min

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# Warning: can't open/read file: check file path/integrity

The OpenCV warning "findDecoder imread_() can't open/read file: check file path/integrity" occurs for multiple reasons:

  1. The path to the image file is incorrect.
  2. The specified extension of the file is missing or incorrect.
  3. The file name contains special characters (e.g. umlauts or accents).

Here is an example of when the warning is shown.

main.py
import cv2

# ⛔️ [ WARN:0@0.004] global loadsave.cpp:244 findDecoder imread_('house1.png'): can't open/read file: check file path/integrity
img = cv2.imread('house.png')

warning cant open read file check file path integrity

There is no file named house.png in the same directory as my main.py script which causes the warning.

One way to resolve the issue is to move the file to the same directory as your Python script.

shell
my-project/
  └── main.py
  └── house.png

If the two files are in the same folder, you can specify a relative path as follows.

main.py
# ✅ No warnings
import cv2

img = cv2.imread('house.png')
The code for this article is available on GitHub

Alternatively, you can use an absolute path to the file.

On Windows, the absolute path might look something like this:

main.py
# ✅ On Windows
import cv2

abs_path = 'C:\\Users\\Borislav\\Desktop\\house.png'

img = cv2.imread(abs_path)

Notice that each backslash \ is escaped with another backslash in order to treat them as literal characters and not as escape characters.

You can also prefix the string with an r to mark it as a raw string.

main.py
# ✅ On Windows
import cv2

abs_path = 'C:\Users\Borislav\Desktop\house.png'

img = cv2.imread(abs_path)
The code for this article is available on GitHub
Strings that are prefixed with r are called raw strings and treat backslashes as literal characters.

You can also use forward slashes / instead of backslashes \ to avoid having to escape each slash.

main.py
# ✅ On Windows
import cv2

abs_path = 'C:/Users/Borislav/Desktop/house.png'

img = cv2.imread(abs_path)

On macOS and Linux, your absolute path might look something like this:

main.py
# ✅ On macOS and Linux
import cv2

abs_path = '/home/bobbyhadz/Desktop/python/house.png'

img = cv2.imread(abs_path)

# Using the os.chdir() method to change to the file's directory

If the issue persists, try to use the os.chdir() method to change the current working directory to the directory that contains the file.

main.py
import os
import cv2

dir_that_contains_file = '/home/borislav/Desktop/bobbyhadz_python'

os.chdir(dir_that_contains_file)

img = cv2.imread('house.png')
The code for this article is available on GitHub

Make sure to update the path to the directory that contains the file.

The os.chdir method will change the current working directory to the specified path.

The example above assumes that you have a house.png file located in the /home/borislav/Desktop/bobbyhadz_python directory.

Once you change to the directory that contains the file, you can pass the filename to the cv2.imread() method.

# Make sure the path is correct

The OpenCV warning is most commonly shown when the path you've passed to the cv2.imread() method is incorrect.

You can use the os.path.exists() method to assert that the path to the file exists.

main.py
import os
import cv2

path_to_file = '/home/borislav/Desktop/bobbyhadz_python/house.png'

assert os.path.exists(path_to_file)

img = cv2.imread(path_to_file)

If the path doesn't exist, you'd get an AssertionError.

shell
Traceback (most recent call last):
  File "/home/borislav/Desktop/bobbyhadz_python/main.py", line 11, in <module>
    assert os.path.exists(path_to_file)
AssertionError

You can also use an if/else statement to check if the path to the file exists.

main.py
import os
import cv2

path_to_file = '/home/borislav/Desktop/bobbyhadz_python/house.png'

if os.path.exists(path_to_file):
    img = cv2.imread(path_to_file)
    print(img.shape)
else:
    print('The specified path does NOT exist')
The code for this article is available on GitHub

The os.path.exists() method returns True if the provided path exists and False otherwise.

# Make sure the specified file extension is correct

Make sure you haven't forgotten to specify the file extension in the path.

main.py
# ✅ Absolute path (Windows)
abs_path = 'C:\\Users\\Borislav\\Desktop\\house.png'

# ✅ Absolute path (macOS/Linux)
abs_path = '/home/bobbyhadz/Desktop/python/house.png'

# ✅ Relative path (Windows, macOS, Linux)
rel_path = './house.png'

Another common cause of the error is specifying an incorrect extension, e.g. jpeg vs jpg or png vs webp.

Make sure the extension of the file is specified in the path and is correct.

# Make sure the path to the file doesn't contain special characters

Another common cause of the warning is when the path to the file contains special characters, e.g. umlauts (ä, ö, ü), accents, newline characters \n, hash # symbols, etc.

If the path to the file contains special characters, try to rename the path components to only contain ASCII (a-z, A-Z) letters, digits (0-9), hyphens - and underscores _.

# Specifying a relative path correctly

If none of the suggestions helped, try to use a relative path to the file.

For example, if the image is located in the same directory as your Python script:

shell
my-project/
  └── main.py
  └── house.png

You would use the following path.

main.py
# ✅ No warnings
import cv2

img = cv2.imread('./house.png')

This assumes that you have the following folder structure.

If the image is located in a subdirectory:

shell
my-project/
  └── main.py
  └── images/
    └── house.png

You would use the following path.

main.py
import cv2

img = cv2.imread('./images/house.png')
The code for this article is available on GitHub

If the file is located one directory up from your Python script:

shell
my-project/
  └── src/
    └── main.py
  └── house.png

You would have to prefix the path with '../'.

main.py
import cv2

img = cv2.imread('../house.png')

The ../ prefix means "go one directory up".

If you need to go two directories up, you would use the prefix twice '../../'.

main.py
import cv2

img = cv2.imread('../../house.png')

The example above assumes that you have the following folder structure.

shell
my-project/
  └── src/
    └── main.py
└── house.png

If none of the suggestions helped, try to move the image file right next to your Python script file (e.g. main.py) and use the following path.

main.py
# ✅ No warnings
import cv2

img = cv2.imread('house.png')

This assumes that you have the following folder structure.

shell
my-project/
  └── main.py
  └── house.png

# Conclusion

To solve the OpenCV warning "findDecoder imread_() can't open/read file: check file path/integrity", make sure:

  1. The specified path to the image file is correct and complete.
  2. The extension of the path is specified and correct.
  3. The file name doesn't contain special characters (e.g. umlauts and accents).

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

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