I'd actually suggest using PATH_INFO to pass around the parameters, as it makes it more likely that browsers will cache it, and not attempt to resubmit, because they see a QUERY_STRING, and shut off caching. (You can also send cache-control headers).

And don't forget your ALT attribute:

printf( '<img src="%s/%s" alt="%s" width="%i" height="%i" />',
    $cgi_url, @image{qw(id description width height)} );
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