Lab experiment
The Compression Test
Two versions of the same picture. One is compressed. Five rounds, getting harder, until you cannot tell.
You will see the same picture twice. One side has been compressed. Pick it. Five rounds, and the compression gets gentler each time until you cannot tell any more.
Use your own photo if you can — the answer only means something on an image you actually care about.
Your photo never leaves your device — the whole test runs in this tab.