У тебя в product.tpl код такой ?
<img id="bigpic" itemprop="image" src="{$link->getImageLink($product->link_rewrite, $cover.id_image, 'large_default')|escape:'html':'UTF-8'}" title="{if !empty($cover.legend)}{$cover.legend|escape:'html':'UTF-8'}{else}{$product->name|escape:'html':'UTF-8'}{/if}" alt="{if !empty($cover.legend)}{$cover.legend|escape:'html':'UTF-8'}{else}{$product->name|escape:'html':'UTF-8'}{/if}" width="{$largeSize.width}" height="{$largeSize.height}"/>