I write a simply CGI page to display gif picture:

        use strict;
        use warnings;
        use CGI;
        use CGI qw(:all);
        my $q = CGI->new;

        print $q->header(-type=>'image/gif',
                 -charset=>'UTF-8');
        print $q->start_html(-title=>'testgif',
                            -author=>'test@test',
                     );

        open(my $F, '<', '1.gif') || die "can not open\n";
        local $\ = undef;
        print <$F>;
        close($F);

        print $q->end_html;
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Well I can see a lot of output when exec this script in command line, but nothing displayed by the WebBrowser. What's the matter?