A self-checkout kiosk is a machine near a shop's exit where the shopper scans and pays for items alone, without a cashier. A scale and a camera watch for items that are not scanned. It is also called a self-service checkout.
The kiosk is a small billing counter. It has a barcode scanner, a touch screen, a payment device and a bagging area with a scale under it. It runs the same retail POS software as the staffed counters, so it charges the same prices.
The difficult part is checking for missed items without a cashier. The kiosk does this in two ways. The first is weight. The store's system knows the weight of every product. When you scan an item and put it in the bagging area, the scale checks that the weight rose by the right amount. The second is a camera above the scanner. It uses computer vision, software that recognises objects in images, to see each item that passes. If it sees an item that was not scanned, or a costly item scanned as a cheaper one, it raises an alert.
Here is how it works at a hypermarket in Visakhapatnam. A shopper scans five items: two packets of pasta, a jar of sauce, a pack of cheese and a box of cereal. The screen shows ₹1,140. The camera sees a sixth item, a ₹220 bottle of olive oil, go into the bag without a scan. The kiosk pauses and asks the shopper to scan it. A staff member who watches six kiosks receives an alert on her handheld device. The shopper scans the oil, and the total becomes ₹1,360. She pays by scanning the UPI QR code on the screen. She could also tap her card on the POS terminal built into the kiosk.
Why do retailers install these kiosks? One staff member can watch six kiosks instead of running one counter. So the queues are shorter at busy times. But retailers also lose more stock at self-checkouts, through honest mistakes and through theft. That is why the camera and the scale are there. It is also why some stores allow self-checkout only for small baskets.
A shopper can also skip the counter completely. With scan and go, she scans the items on her own phone as she shops. In a cashierless store, cameras record what she takes, and she simply walks out.