A fan has claimed Nickelodeon used his SpongeBob SquarePants artwork without his permission.
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Matt Salvador, 17, says the art was featured in an advert for the show which was aired in June.
His artwork, uploaded online in 2016, is drawn in the style of a background used in a typical episode.
Various YouTube channels have uploaded the video, which the fan says shows the same artwork, but with his signature in the bottom-right corner removed.
The show is produced by Nickelodeon and shown on its TV channel. The company has been approached for comment.
Mr Salvador, who goes by Lolwutburger online, tweeted about the situation in the hope that Nickelodeon would take action.
His tweet has been liked more than 25,000 times on Twitter, with the vast majority of comments criticising Nickelodeon.
Mr Salvador said he was "surprised and a bit peeved" about the artwork being used, and claimed Nickelodeon had removed his signature.
"I'm still awaiting some sort of apology or explanation from Nickelodeon," he said, "as that's the least they can do.
"If they want to give me some sort of compensation, I'm fine with that too.
"But my advice to all artists is to always put some sort of identifier such as a watermark on their works so they'll be able to prove they were the original creators."
The two backgrounds compared
Mr Salvador claimed his work was originally uploaded to art-sharing website DeviantArt in 2016.
It has since become a popular computer background image or wallpaper: at the time of writing, it ranks as the top Google Image search result for "SpongeBob background". (It is third on DuckDuckGo, and seventh on Bing.)
The drawing is in the style of the SpongeBob SquarePants background setting of Bikini Bottom which appears in most episodes. Typically this will be an underwater scene, with cartoon flowers in the distance.
The following is the image which Mr Salvador says he originally drew, with a signature in the bottom right-hand corner:
And below is the image used in a promotional video by Nickelodeon below, which does not feature the signature.