By default we convert all images uploaded into Listing Mirror to JPG before sending to the marketplaces. This is to best ensure that all marketplaces accept your images without requiring action on your part.
However, we understand that you may want to upload PNG images, specifically on your own Shopify webstore. You now have the option to send both JPG and PNG images to Shopify!
Simply go into the Advanced Settings for your Shopify integration and select the option to 'send raw image'. This will send the image in its original format to Shopify directly from Listing Mirror.