Here's another (less appealing ... err.. worse) solution using raw regular expressions:

Try this... 
my $font_tag_match = m{
           # Tags in pairs like <foo>content</foo>
           \<
           \s*
              (<font[a-z:\=]>+)
              [
                 \s*<[a-z:]>*
                 \s* = \s*
                 [ ' <[^']>* ' | " <[^"]>* " ]
              ]*
           \s*
           \>

           [ <[^<>]>* | <xml> ]*

           \< \s* / \s* font \s* \>
      }x;

# remove all text that is not between a pair of <font> tags..
$input_data =~ s/^$font_tag_match//mg;

[download]
Unfortunately I had to make up the code without any bit of testing as I don't have the means to do so on this particular PC (Have to reboot my Win2000 OS as the MS-DOS command prompt wouldn't work for some reason ;/)

_____________________ 
# Under Construction

[download]

In reply to Re: keeping one pattern but removing all else from a string by vladb
in thread keeping one pattern but removing all else from a string by Anonymous Monk

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