SubtractEvaluateOperator  539 Magick++/lib/Magick++/Include.h   using MagickCore::SubtractEvaluateOperator;
SubtractEvaluateOperator 1052 magick/option.c     { "Subtract", SubtractEvaluateOperator, UndefinedOptionFlag, MagickFalse },
SubtractEvaluateOperator  373 magick/statistic.c     case SubtractEvaluateOperator: