my $section = [ 
    [ "image1.gif" , "mark('a' ,1)" ],
    [ "image2.gif" , "mark('a' ,2)" ],
];

my $parsed = '[ ' . 
             join( ' , ', map { '[ "' . join('" , "', @$_) . '" ]' } @$section ) .
             ' ]';

##</code><code>##

[ [ "image1.gif" , "mark('a' ,1)" ] , [ "image2.gif" , "mark('a' ,2)" ] ]

##</code><code>##

use JSON;

my $json = JSON->new;

my $section = [
    [ "image1.gif" , "mark('a' ,1)" ],
    [ "image2.gif" , "mark('a' ,2)" ],
];

my $parsed = $json->objToJson( $section );