Question: Someone published a photo of Rabbonim sitting at a rabbinic convention? May I copy this photo?

Answer: Rav Yosef Chaim Zonnenfeld zt"l allowed taking a photo of another person without his permission (provided, of course, that the person will not be embarrassed, etc.). He does not consider copying the image of someone as benefitting from him. The mere look (mar'eh) of something, which does not involve a mental creation, is not considered "intellectual property." Hence, the photo is also not considered the intellectual property of the photographer to prohibit copying for personal use.

However, if the photograph required the photographer's creativity to achieve, then it could be considered his "intellectual property" and would be prohibited to copy. Similarly, if the photographer enhanced the photo significantly, it would be prohibited to copy, since it is now a product of his creativity.

Regardless, since the photographer invested effort in taking the picture, it is prohibited to copy it for commercial purposes that might impinge upon the photographer's earning. This would be a violation of hasagas hagevul, professional practices, dina d'malchusa, and benefitting financially from another's toil.

(Emek Hamishpat, Zechuyos Yotzrim intro. 7:1-5; ch. 36:7,19,25)