Use an example with a known source
Take a photograph you own that appears on your public portfolio. Search the same file in each service. Note whether the results lead to the portfolio, a repost, a similar subject or nothing useful. Keep all four outcomes in your comparison.
Evaluate the output
- Can you open a page containing the actual photograph?
- Does the tool help with a crop or edited copy?
- Are related objects useful for your question?
- Can you repeat the process without losing source context?
If you want to buy a similar lamp, related visual results may be valuable. If you want to establish where your lamp photograph was reused, matching the actual composition matters more.
Avoid a universal winner
Index coverage changes and a small test is not a benchmark of the whole web. Consult each provider's current documentation for capabilities and limits. Choose the method that produces reviewable evidence for your task, and use a second method when the first leaves an important question unresolved.
Continue with copy search and face search explained.