Every antique identifier on the App Store does roughly the same thing: you take a photo, it names the object and gives you a price. Read their reviews and one complaint keeps coming back. The answer sounded certain, the price was precise, and both were wrong.
Before I wrote any code for Backmark I wanted to know how often that happens, so I ran the vision model over a set of labelled museum photos, pieces where the maker and the date are known.
What the test showed
When a maker's mark was visible in the photo, the model named the maker correctly 9 times out of 10. Without a mark it got 4 out of 7. That is not bad. The problem was elsewhere: the wrong answers came with 85 to 95 percent confidence, the same numbers the right answers had. Silver hallmarks were worse still: the same photo read differently depending on how the prompt was worded.
And museum photos flatter a model. They are lit well, shot straight on, on a clean background. A photo taken on a kitchen table will do worse.
So a confidence percentage from the model tells the person nothing. Showing it would only make a wrong answer look more trustworthy.
What Backmark shows instead
Every result says one of three things: Strong match, Possible match or Not sure yet, followed by the reason in a sentence.
A Strong match is not the model's opinion. It has rules. The maker's mark has to be in the photo, and its text has to spell the maker. The mark is read twice, in parallel, and both readings have to agree. If any of that fails, the best the app can say is Possible match.
With those rules in place I ran the museum set again on three models, and then on ten amateur photos found online. No wrong answer came out as a Strong match on any of them.
Prices get the same treatment
Values are always a range, and each range says what it is based on. When the app is not sure what an item is, and one of the possibilities could be worth a lot, it doesn't invent a number. It says the item may be valuable and is worth a professional appraisal, and shows the other possibilities side by side.
It is a less exciting answer than a confident price. It is also the one that doesn't cost someone money.