Replace image urls(absolute instead of relative) by using filter in single page

Something like this should do it, you may have to fiddle with the preg_replace() to get it to work the way you need, but the concept (and, more importantly imo, the regex, is there).

if( is_single() ) {
    add_filter( 'the_content', 'wpse44503_filter_content' );
}

function wpse44503_filter_content( $content ) {
    $regex = '#src=("|\')'.
        '(/images/(19|20)(0-9){2}/(0|1)(0-9)/[^.]+\.(jpg|png|gif|bmp|jpeg))'.
        '("|\')#';
    $replace="src="".get_site_url( $2 ).'"';

    $output = preg_replace( $regex, $replace, $content );

    return $output;
}

That’s untested, and I wrote it right into the solution box, so make sure you debug thoroughly and such.