Hello,

Basically the product images are controlled by WooCommerce and WoodMart theme doesn’t influence this. The size of the thumbnail you set should be larger than the size of the product thumbnail displayed on the shop page. If the thumbnail size is smaller than what the default size expects, it may appear blurry or not display correctly. You can find the sizes used on the demo here: https://xtemos.com/docs/woodmart/faq-guides/image-size-content-alignment-product-grid/

Here is the WooCommerce Manual:
https://woocommerce.com/document/fixing-blurry-product-images/

Best Regards.