A mobile inventory robot system generates an inventory map of a store and a product database when a mobile inventory robot is manually navigated through the store to identify items on shelves, a location for each of the items on the shelves, and a barcode for each of the items. The system performs inventory of the items by navigating through the store via the inventory map, capturing a shelf image, decoding a product barcode from the captured shelf image, retrieving a product image for the decoded product barcode from the product database, segmenting the captured shelf image to detect an image of an item on the shelves, determining whether the detected image matches the retrieved image and, if not, setting an out-of-stock flag for an the item.