Some conferences I've attended provide stickers to put on your badge and if you don't want to be photographed/published the conference organizers may pay attent

Some conferences I've attended provide stickers to put on your badge and if you don't want to be photographed/published the conference organizers may pay attention with respect to their publicity photos. Of course, others snapping pics with their cell phones may not. (And, in Germany as well as other countries, I've never seen explicit warnings about not publishing photos of people at a conference without permission.). Most people are pretty reasonable and aren't aggressive with their picture taking. But there are almost certainly photos of you online whatever the local country laws may say.