3 # giftopnm fall$* | pnmgamma 2 | pnmscale 2 | pnmsmooth | pnmscale 2 | pnmsmooth | pnmdepth 255 >fall.ppm
4 giftopnm over$* >over.pbm
5 pbmmask -expand over.pbm >over.mask
6 giftopnm $* | pgmtoppm -map color.ppm | pnmscale 4 | pnmcomp -invert -alpha over.mask over.pbm