eval '(exit $?0)' && eval 'exec perl -S $0 ${1+"$@"}' && eval 'exec perl -S $0 $argv:q' if 0;

# convert colour files produced by PAW into BW styled files 
# -- Uta 1.11.00, outer Perl frame based on Naomi's script
# -- Naomi 14.3.01, replaced colour 'black' (not always defined), and 
#	added grayscaling 

$use_gray = 1;
$need_help = 0;
foreach $text (@ARGV)  {
  last if (!($text=~/^-/));
  if ($text=~/-b/) {$use_gray = 0}
  else {print "Unrecognized option $text \n"; $need_help = 1};
  shift(@ARGV);
}
goto HELP if ($need_help);
goto HELP if ($#ARGV != 1);
  
if (-e $ARGV[1]) {
  print "\n >>> Output file $ARGV[1] already exists, overwrite? [<CR>=no] ";
  $text = <STDIN>;
  print "\n";
  exit(0) if (!($text=~/^\s*y/i));
}
open (COLOR,"<$ARGV[0]"); open (BW,">$ARGV[1]");
while (<COLOR>) {
  if ($use_gray) {
    s/\bsetrgbcolor\b/add add 3 div setgray/g;
  } else {
    s/\bsetgray\b/pop 0 setgray/g;
    s/\bsetrgbcolor\b/pop pop pop 0 setgray/g;
  }
  print BW;
}
close(COLOR); close(BW);

exit(1);

HELP:
print "\nUsage:   bw_convert [-b] <colour_file> <bw_file>  \n";
print "\n  -b       : convert all colours and grays to black\n";
print "\n"; exit(0);