Is there anyway to change this href to image url? Its from Magento Checkout module copied to my theme Magento_Checkout/web/template/minicart/item/default.html

<a data-bind="attr: {href: product_url, title: product_name}" tabindex="-1" class="product-item-photo" data-fancybox>
    <!-- ko foreach: $parent.getRegion('itemImage') -->
    <!-- ko template: {name: getTemplate(), data: item.product_image} --><!-- /ko -->
    <!-- /ko -->
</a>

I was trying to change to this:

<a data-bind="attr: {href: product_image, title: product_name}" 

but no success.