ImageInfo errors

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I posted a recent SOPW and the code I've been told to use is below. For the life of me I cannot get imageinfo to parse my image file, it constantly errors out about division by zero. My test $h and $w printout are blank.

I can access the image URL in my browser just fine, so it can't be a permission problem. Anyone have any ideas what might be wrong?

use Image::Info qw(image_info dim);
my $img_info = image_info("http://www.myurl.org/pictures/$pic_id.jpg")
+;
my ($h, $w) = dim($img_info);

print "$h and $w, check the URL of image at http://www.myurl.org/pictu
+res/$pic_id.jpg";

my ($max_width,    $max_height   ) = (800, 600);
my ($width_factor, $height_factor) = ($max_width/$width, $max_height/$
+height);

if ($width_factor < 1 || $height_factor < 1) {
   my $factor = ($width_factor < $height_factor ? $width_factor : $hei
+ght_factor
   );

   $width  = int($width  * $factor + 0.5);
   $height = int($height * $factor + 0.5);
}
[download]

Comment on ImageInfo errors Download Code

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Re: ImageInfo errors by Joost (Canon) on Feb 22, 2007 at 20:26 UTC
Image::Info doesn't download images from URLs, it only supports local files. so you're probably going to get a height and width of zero. Ofcourse you could have tested for that yourself (from the docs): `my $info = image_info("image.jpg"); if (my $error = $info->{error}) { die "Can't parse image info: $error\n"; }` [download] See also LWP::Simple "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply] [d/l]
Re: ImageInfo errors by zentara (Cardinal) on Feb 22, 2007 at 21:39 UTC
To give an example of what Joost said: `#!/usr/bin/perl use warnings; use strict; use LWP::Simple; use Image::Info qw(image_info dim); my $data = get("http://www.learntogoogle.com/images/addform.jpg"); # this will print binary junk #print "$data\n"; my $info = image_info( \$data ); if (my $error = $info->{error}) { die "Can't parse image info: $error\n"; } my($w, $h) = dim($info); print "$w $h\n";` [download] I'm not really a human, but I play one on earth. Cogito ergo sum a bum	[reply] [d/l]
Re^2: ImageInfo errors by ikegami (Patriarch) on Feb 22, 2007 at 22:38 UTC
You could save time by just downloading the first 1KB of the image. (IIRC, the location of the image size varies in JPGs, but it's very near the beginning 99.999% of the time.) This can be done using the HTTP `Range` header field. A sample value would be `bytes=0-1023`.	[reply] [d/l] [select]