name 'pre_nms_rois' is not defined

This error message means that there is a variable or object named "pre_nms_rois" that is being referenced in the code, but it has not been defined or declared anywhere in the program.

To fix this error, you need to define or declare the "pre_nms_rois" variable before it is used in the code. You may need to check the spelling and ensure that the variable is being used in the correct scope.