Fix cv2.imwrite on non-ASCII paths

[CCRcmcpe]

Previous PR #6979 fixed imread. But I discovered imwrite is also broken: when saving a image, Unicode characters in the path are converted to meaningless characters, or it does not save the image at all.
Also moved the custom imread to utils.general.

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Refactoring OpenCV image read/write functions for compatibility with non-latin filenames.

📊 Key Changes

• Removed direct import cv2 statements from multiple files (detect.py, hubconf.py, and datasets.py).
• Re-defined cv2.imread and cv2.imwrite functions with custom Chinese-friendly versions in utils/general.py.
• Replaced original OpenCV image read/write calls with new custom functions across different modules.

🎯 Purpose & Impact

• 👨‍💻 Developers: Simplifies codebase by centralizing custom OpenCV functions, reducing direct imports, and remapping functions in a single location.
• 🌍 Global Users: Enhances functionality for users with non-latin filenames, offering broader international support for image file operations.
• 🚀 Performance: Streamlined interoperability with OpenCV without altering performance or functionality for existing users with latin-based filenames.

[github-actions]

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[CCRcmcpe]

[glenn-jocher]

@CCRcmcpe ok got it. What we should do then is this. Create the two functions in general.py and then assign them to cv2:

def imread(path):
    return cv2.imdecode(np.fromfile(path, np.uint8), cv2.IMREAD_COLOR)


def imwrite(path, img):
    try:
        cv2.imencode(Path(path).suffix, img)[1].tofile(path)
        return True
    except:
        return False


cv2.imread, cv2.imwrite = imread, imwrite

Then everywhere that imports cv2, change it to:

from utils.general import cv2

And finally delete all other changes from #6979 and this PR. Then everything should work well with a minimum of customizations to the code.

[glenn-jocher]

@CCRcmcpe PR is merged. Thank you for your contributions to YOLOv5 🚀 and Vision AI ⭐

[CCRcmcpe]

@CCRcmcpe ok got it. What we should do then is this. Create the two functions in general.py and then assign them to cv2:

def imread(path):
    return cv2.imdecode(np.fromfile(path, np.uint8), cv2.IMREAD_COLOR)


def imwrite(path, img):
    try:
        cv2.imencode(Path(path).suffix, img)[1].tofile(path)
        return True
    except:
        return False


cv2.imread, cv2.imwrite = imread, imwrite

Then everywhere that imports cv2, change it to:

from utils.general import cv2

And finally delete all other changes from #6979 and this PR. Then everything should work well with a minimum of customizations to the code.

Great! I'm relatively new to python so I don't know can actually import like this.

[glenn-jocher]

@CCRcmcpe it's a bit of an experimental approach, but yes you can overwrite imports, or most any other variable/method after they are defined.