package Image::Signature::Grayscale; our @coef = qw(0.3 0.59 0.11); sub to_gray { $_[0]*$coef[0] + $_[1]*$coef[1] + $_[2]*$coef[2] } use Exporter; our @ISA = qw(Exporter); our @EXPORT = qw(to_gray); 1;