Hi I want to call a subroutine ImageNotDark. I want to pass an Image::Magick object ($pic). By design, the object is not changed inside the subroutine. My problem is that I am not passing the image object correctly.

# Convert to Image::Maggick image
my $pic = Image::Magick->new(magick=>'jpg');  #   create new image obj
+ect
$pic->BlobToImage($img);  #convert the grabbed blob image to Image::Ma
+gick object

## test point A

#pass the $pic object to the subroutine and measure image darkness.
my $test = ImageNotDark ($pic);  #
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The code snippet at the start of the subroutine is as follows:

sub ImageNotDark  {
# Argument is one reference to an image object.
# ImageNotDark compares the image with a blank black canvas.  If the c
+omparison is
# above the defined threshold, the image is bright enough to send (not
+ dark).
# the return value is true if the images is bright enough.

    my $iutImage = Image::Magick->new;  #the image tested for darkness
    $iutImage->Read(@_);  # get the image under test (iut)
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So the debugger shows that $iutImage is not initialised. At test point A, I temporarily added code to save the $pic image to a file. I was able to confirm that $pic holds a valid image. So I am reasonably certain the problem is the way I call the subroutine and attempt to pass the image. Any tips would be much appreciated.

SOLVED with the answer below from Haukex. I applied the option on the last line.
You don't need to construct a new Image::Magick over the argument passed to the subroutine. The normal way to handle arguments is (see perlsub):

sub ImageNotDark {
  my ($iutImage,$arg2,$arg3,...) = @_;
  # --OR--
  my $iutImage = shift;
  my $arg2 = shift;
  ...
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Or, if your intention were to work with a copy of the image in the subroutine, you could simply do my $imgCopy = $_[0]->Clone(); inside the subroutine.