Threshold        1534 magick/composite.c   composite->red=Threshold(p->red,q->red,threshold,amount);
Threshold        1535 magick/composite.c   composite->green=Threshold(p->green,q->green,threshold,amount);
Threshold        1536 magick/composite.c   composite->blue=Threshold(p->blue,q->blue,threshold,amount);
Threshold        1537 magick/composite.c   composite->opacity=QuantumRange-Threshold(p->opacity,q->opacity,
Threshold        1540 magick/composite.c     composite->index=Threshold(p->index,q->index,threshold,amount);