Assuming the image name doesn't have any spaces in it, you could do it like this:

if ( $url =~ m!/([^/]+\.(?:jpe?g|gif|png|tiff?)\b)!i ) {
    print "Found $1\n";
}
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The way this works is as follows:

m!            # Use an alternate delimiter.
  /           # Match a '/' character to anchor off of.
  (           # Start a capturing parenth.
    [^/]+     # Match any number of non-'/' characters.
    \.        # Match the '.' character.
    (?:       # Group or constrain without capturing.
        jpe?g # jpg or jpeg.
      | gif   # or gif
      | png   # or png
      | tiff? # or tif or tiff
    )         # End the grouping/constraining parens.
    \b        # Make sure that tiff isn't tiffany, for
              # example.
  )           # End the capture.
!ix           # Case insensitive /i (Ignore the x, it's only
              # necessary in this expanded example.
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If the URL is encoded, so that spaces have become '+' characters, etc., you will need to decode the URL first, or else filenames containing spaces will be mangled. That particular issue isn't a regexp issue, just the way URL's get encoded.

If you want to avoid regexes, you could use the URI module's path method in combination with the File::Spec::Unix module's splitpath function to get the filename. For example:

#!/usr/bin/perl -w

use strict;
use File::Spec::Unix;
use URI;

#
# url:      http://www.made_up_name.com/somepath/script.php/image.jpg?
+p=1&q=2#name
#
# $u->scheme:   http
# $u->userinfo: (undef)
# $u->host:     www.made_up_name.com
# $u->port:     80
# $u->path:     /somepath/script.php/image.jpg
# $u->query:    p=1&q=2
# $u->fragment: name
#
my $url = join(
    '://', 'http',
    join(
        '/',
        'www.made_up_name.com',
        'somepath',
        'script.php',
        join( '?',
            'image.jpg',
            join( '#', join( '&', 'p=1', 'q=2' ), 'name' ) )
    )
);
my $u = URI->new($url);

#
# $u->path: /somepath/script.php/image.jpg
#
# $volume:      ''
# $directories: /somepath/script.php/
# $file:        image.jpg
#
( my $volume, my $directories, my $file ) =
  File::Spec::Unix->splitpath( $u->path );

printf
  << "URI_PARTS", $url, ( defined( $u->scheme ) ? $u->scheme : '(undef
+)' ), ( defined( $u->userinfo ) ? $u->userinfo : '(undef)' ), ( defin
+ed( $u->host ) ? $u->host : '(undef)' ), ( defined( $u->port ) ? $u->
+port : '(undef)' ), ( defined( $u->path ) ? $u->path : '(undef)' ), (
+ defined( $u->query ) ? $u->query : '(undef)' ), ( defined( $u->fragm
+ent ) ? $u->fragment : '(undef)' );
URI PARTS
    URL:      %s
    
    SCHEME:   %s
    USERINFO: %s
    HOST:     %s
    PORT:     %s
    PATH:     %s
    QUERY:    %s
    FRAGMENT: %s
URI_PARTS
printf
  << "PATH_PARTS", ( defined($u->path) ? $u->path : '(undef)' ), ( def
+ined($volume) ? $volume : '(undef)' ), ( defined($directories) ? $dir
+ectories : '(undef)' ), ( defined($file) ? $file : '(undef)' );
PATH FRAGMENTS
    PATH:        %s
    
    VOLUME:      %s
    DIRECTORIES: %s
    FILE:        %s
PATH_PARTS
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Another way to look at it, at least. Hope that helps.

You forgot about the path_segments method.

C:\>perl -MURI -e"die $_= ( URI->new( shift )->path_segments )[-1] " /
+somepath/script.php/image.jpg
image.jpg
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MJD says "you can't just make shit up and expect the computer to know what you mean, retardo!"

I run a Win32 PPM repository for perl 5.6.x and 5.8.x -- I take requests (README).

** The third rule of perl club is a statement of fact: pod is sexy.

$url =~ /.+\/(.+)/;
$image_name = $1;
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If you wanted to be sure to only match on a JPEG, you could use (.+\.jpg) for the part in parentheses instead.

You really should check out perlrequick, perlretut, and perlre to learn more about regexes, because I left out a lot in my above explanation. They're not that hard to learn most of the basics, and a lot of fun I think.

$_ = $url;
($filename) = /([^\/]*)$/;
print "filename is $filename\n";
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#!/usr/bin/perl
use strict;
use Dumpvalue;
my $dumper = new Dumpvalue;

my $url_string = "http://www.made_up_name.com/image.jpg there might be
+ text between as well since an url like so: http://www.made_up_name.c
+om/image2.gif says to me this might be needed in a larger context so 
+lets try with a string http://www.made_up_name.com/image3_the%20third
+.png and see what we get.";
my @images = map{split/\//;pop @_} $url_string =~ m!(http://\S+/\S+\.[
+a-z]{3,4})!g;
$dumper->dumpValues(\@images);
exit;

OUTPUTS:
0 ARRAY(0x155ac4c)
    0 'image.jpg'
    1 'image2.gif'
    2 'image3_the%20third.png'
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