c:>type gp4.pl
use Imager;
my $image_source = "\\c\\perl\\graphics\\" . shift . ".bmp";
my $image = Imager->new;
$image->read(file=>$image_source)
  or die "Cannot load $image: ", $image->errstr;
$width =  $image->getwidth();
$height = $image->getheight();
print "Image dimensions: height = $height, width = $width\n";

$x = [ 10 ];
$y = [ 10 .. 15 ];
@colors = $image->getpixel( x=>$x, y=>$y, type=>'8bit' );
for $color ( @colors )
{
  ( $r, $g, $b, $a ) = $color->rgba();
  print " shade = $r, $g, $b\n";
}

c:>gp4 d2044
Image dimensions: height = 348, width = 349
Can't call method "rgba" on an undefined value at gp4.pl line 15.