-2 opencv encoding_error ai_generated true

cv2.error: OpenCV(4.8.0) /modules/imgcodecs/src/loadsave.cpp:734: error: (-2:Unspecified error) could not find a writer for the specified extension in function 'cv::imwrite_'

ID: opencv/imwrite-format-unsupported

Also available as: JSON · Markdown · 中文
93%Fix Rate
86%Confidence
1Evidence
2023-02-28First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
4.5.0 active — — —
4.6.0 active — — —
4.8.0 active — — —

Root Cause

The file extension in the output path is not recognized or supported by OpenCV's image writing codecs (e.g., .bmp, .jpg, .png are supported, but .webp or .tiff may be missing).

generic

中文

输出路径中的文件扩展名不被OpenCV的图像写入编解码器识别或支持（例如，支持.bmp、.jpg、.png，但可能缺少.webp或.tiff）。

Official Documentation

https://docs.opencv.org/4.8.0/d4/d5e/group__imgcodecs.html

Workarounds

  1. 95% success Use a supported extension like '.png' or '.jpg': `cv2.imwrite('output.jpg', img)` 
    Use a supported extension like '.png' or '.jpg': `cv2.imwrite('output.jpg', img)`
  2. 80% success Rebuild OpenCV with the desired format support, e.g., for WEBP: `cmake -DOPENCV_EXTRA_MODULES_PATH=../opencv_contrib/modules -DBUILD_WEBP=ON ..` 
    Rebuild OpenCV with the desired format support, e.g., for WEBP: `cmake -DOPENCV_EXTRA_MODULES_PATH=../opencv_contrib/modules -DBUILD_WEBP=ON ..`
  3. 85% success Use an external library like Pillow to convert the image to a supported format before saving with OpenCV. 
    Use an external library like Pillow to convert the image to a supported format before saving with OpenCV.

中文步骤

  1. Use a supported extension like '.png' or '.jpg': `cv2.imwrite('output.jpg', img)`
  2. Rebuild OpenCV with the desired format support, e.g., for WEBP: `cmake -DOPENCV_EXTRA_MODULES_PATH=../opencv_contrib/modules -DBUILD_WEBP=ON ..`
  3. Use an external library like Pillow to convert the image to a supported format before saving with OpenCV.

Dead Ends

Common approaches that don't work:

  1. Installing libwebp-dev via apt but not rebuilding OpenCV with WEBP support. 70% fail

    Installing additional image libraries without rebuilding OpenCV does not add codec support.

  2. Converting the image to float32 before saving. 90% fail

    Changing the image data type does not affect codec availability.

  3. Converting the image to grayscale before saving. 80% fail

    Using a different color space does not enable unsupported formats.