BusinessMind does not have a limit on images sizes but Shopify does. This means when adding images to BusinessMind you will need to adhere to Shopifys image limits.
Your image should be no larger than 4472 x 4472. Anything larger will not be see on your Shopify site. In addition SHopify typically recommends using 2048 x 2048 pixels for square product photos Please see below for more detailed info from Shopifys help center: