A campaign video created by supporters of US presidential candidate Bernie Sanders has been criticised for failing to credit the work of Singaporean photographer John Clang, from whom it drew inspiration.
The one-minute video, titled Together, was uploaded on Vimeo two weeks ago and has since gone viral, racking up more than 2.6 million views.
With the tagline "America should work for all of us #votetogether", the clip has been praised for its visually-arresting stop-motion technique that features portraits of different faces torn in half.
But its style and concept bears uncanny resemblance to a similar video done by the New York-based Mr Clang, 42, who shot a stop-motion ad in November 2009 to bring awareness to the United Nations' climate change conference in Copenhagen.
Titled Hopehagen, the 30-second clip was a collaboration between Mr Clang, 42, and advertising agency Ogilvy & Mather.
Mr Clang, speaking to photography blog PetaPixel, said he was alerted by friends to the Together video last week, and was bothered by how it had failed to mention his work.
A mention was later added to the Sanders video credits, which read: "Special thanks to John Clang for your beautiful photo/stop-motion technique inspiration."
But Mr Clang was critical of the fact that the video's director, Jonathan Olinger of the storytelling agency Human, did not acknowledge his work from the start.
"I admire Jonathan Olinger's passion in creating good concerted efforts for great causes," Mr Clang told PetaPixel. "His passion is, what I always believe in, much needed in this artistry. I would have hoped he had approached me earlier to discuss this project, especially (as) we are both New Yorkers.
"Understandably sometimes when one sees something that resonates with them, it's difficult to erase from their mind. I think I deserve... respect and acknowledgement from him. I respect what he does and I do hope we both can be friends."
Mr Clang's agency, the CollectiveShift, also left a comment on the Facebook video to explain its stance.
In a Facebook post after the PetaPixel article was published, Mr Clang said artists and creators should not be faulted for trying to defend the rights to their work.
"We're not talking about the technique of collage here, as many has pointed out that it has been done by students in schools and goes back decades. I agree wholeheartedly," he wrote.
"My work has always been idea-driven and I really can't say more if you fail to see the similarities in those works. I wish I didn't have to find out about it this way."