error: ‘CV_WINDOW_FREERATIO’ was not declared in this scope

This error message typically occurs when the code is trying to use the constant "CV_WINDOW_FREERATIO" in a scope where it is not defined.

To resolve this error, you may need to include the appropriate header file that declares the constant. For example, if you are using OpenCV, you may need to include the "opencv2/highgui/highgui.hpp" header file.

Alternatively, you may need to check if the constant is spelled correctly and if it is available in the version of the library you are using.

If you are still having trouble resolving the error, please provide more context and code snippets so that we can better assist you.