error: ‘CV_WINDOW_AUTOSIZE’ was not declared in this scope

This error occurs because the symbol CV_WINDOW_AUTOSIZE is not declared in the scope of the program. To fix this issue:

  1. Include Necessary Libraries: Ensure that the required OpenCV libraries are included at the beginning of your code. cpp #include <opencv2/highgui/highgui.hpp>

  2. Namespace Declaration: Use the cv namespace or specify the namespace for OpenCV functions and symbols. cpp using namespace cv;

  3. Check OpenCV Version: Verify the version of OpenCV being used in the program. For newer versions, CV_WINDOW_AUTOSIZE might have been deprecated or replaced with other constants.

  4. Verify Function Usage: Confirm the correct usage of CV_WINDOW_AUTOSIZE in the context of the code. Ensure it's being used in the right place and manner within the OpenCV functions.

  5. Compiler or Configuration Errors: Check if there are any issues related to the compiler or configuration settings that might be affecting the inclusion of OpenCV libraries or symbols.

  6. Library Linking: Ensure that the OpenCV library is correctly linked with your project or code, as improper linking can cause symbols like CV_WINDOW_AUTOSIZE to be unresolved.

Make sure to address these points in your code to resolve the 'not declared in this scope' error related to CV_WINDOW_AUTOSIZE.