There’s a new tool to take down terrorism images online. But social media companies are wary of it.

President Barack Obama suggested that extremist information spread online inspired a Florida man to commit the deadliest mass shooting in US history at a gay nightclub in Orlando — the latest in a long line of terrorist attacks in which Islamist propaganda played some role in radicalizing the assailant. Now a Dartmouth College researcher and a nonprofit group say they have created a technology that can help Internet companies instantly detect images and videos generated by terrorists and their supporters and remove them from their platforms.

It is, they say, a way to cleanse popular online sites of gory videos and propaganda from the Islamic State, which is also known as ISIS and Daesh, that can serve to incite and inspire people to commit acts of violence. “If you could search out the beheading videos, or the picture of the ISIS fighter all in black carrying the Daesh flag across the sands of Syria, if you could do it with video and audio, you’d be doing something big,” said Mark Wallace, chief executive of the Counter Extremism Project (CEP), a nonpartisan policy group. “I believe it’s a game-changer." The White House has signaled its support. But a number of major social media companies are wary of the idea. They say there is no clear consensus in the United States, and globally, as to what constitutes a terrorist image, and they might end up expunging material posted by researchers or media organizations. And, they say, once a database is created, governments around the world will place additional data requests on them — and some countries’ will probably demand the removal of legitimate political content under the guise of fighting terrorism.