use GD::Simple;
my $png = GD::Image->newFromPng('test.png');  my @sw; my $pdata=''; 
my ($bx, $by) = $png->getBounds; 
my @col;                                             # foreground colors
  for (0..$png->colorsTotal)
  { my ($r,$g,$b) = $png->rgb($_);
    push (@col,$_) unless ($b>128 || $r>128);        
  }
$pdata |= ~$png->wbmp($_) foreach (@col);
our $zlen=int(($bx+7)/8);                            # number of Bytes per line
  my $pos=6; my $y=0;                                # position after Header of WBMP
  while ($pos<length($pdata))
  { $sw[$y]=''; 
    for (1..$zlen) {$sw[$y].=sprintf("%08b",ord(substr($pdata,$pos++,1))); }       # convert binary data into string
    $y++;  
  }