I have a question about the Imager package. This is ActiveState v5.12.4 with Win7Pro on a 64-bit Gateway SX-2841. I would like to access the pixel values from a BMP image. 
c:>type gp1.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;
for $y ( 10 .. 15 )
{
  $color = $image->getpixel( x=>$x, y=>$y, type=>'8bit' );
  ( $r, $g, $b, $a ) = $color->rgba();
  print " shade = $r, $g, $b\n";
}

c:>gp1 d2044
Image dimensions: height = 348, width = 349
 shade = 238, 238, 238
 shade = 255, 255, 255
 shade = 255, 255, 255
 shade = 238, 238, 238
 shade = 238, 238, 238
 shade = 238, 238, 238
c:>

[download]
So far, so good. It is said that I can also use the getpixel invocation directly as the method reference to run rgba(). 
c:>type gp2.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;
for $y ( 10 .. 15 )
{
  ( $r, $g, $b, $a ) =
     $image->getpixel( x=>$x, y=>$y, type=>'8bit' )->rgba();
  print " shade = $r, $g, $b\n";
}

c:>gp2 d2044
Image dimensions: height = 348, width = 349
 shade = 238, 238, 238
 shade = 255, 255, 255
 shade = 255, 255, 255
 shade = 238, 238, 238
 shade = 238, 238, 238
 shade = 238, 238, 238

[download]
Very good. But now it seems like a lot of work to call getpixel separately for each pixel. The 'draw' tutorial says that I can pass a reference to a list of pixel addresses to getpixel(). I should get back a list of references to a color method. I tried it this way. 
c:>type gp3.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:>gp3 d2044
Image dimensions: height = 348, width = 349
Can't call method "rgba" on an undefined value at gp3.pl line 15.

[download]
No luck. It seems that the elements of @colors are undefined. I presume something is wrong with the getpixel() call. OK. So maybe if one axis is a reference, then both have to be. 
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.

[download]
Still doesn't work. What am I missing?

In reply to Using Imager getpixel by LloydRice

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