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);  #
[download]

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)
[download]

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;
  ...
[download]

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.

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.