Your problem isn't well defined. How much variation can there be? If you have to support all HTML possibilities, you'd be much better of using a parser.

Anyway, here's an untested attempt. Most likely, it breaks on your second example:

my (undef, $new, $hit) = $in =~ m{
    <td><img \s+ src \s* = \s* 
    (["']) foo[.]jpg \1 >
    (<a \s+ href \s* = (["']) [^"']* \4 >
     [^<]* </a>}ix;
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Abigail