Yes, if you’ve added a grocery via barcode scan, the system has sufficient information to show the correct associated image. This is due to the fact that users typically do not agree on what e.g. “milk” is, and therefore also not on what image should go for that item.
A barcode identifies a special variant of a grocery, as they are unique across different brands and packages sizes. Therefore Grosh knows which image (and other variant information) to show when you add the item using the barcode.
All grocery items in Grosh are shared across users, so the system gets smarter as more grocery items are added by users. To register grocery information for a barcode, you can scan the barcode and add the item to your list. Once that’s done you can edit the information, e.g. add a missing image or add a missing package size.