(CNN) It was supposed to be a campaign to help a reputable French art school raise its profile in the United States but it went terribly wrong.

The Émile Cohl art school in Lyon was forced to apologize after students noticed their faces had been digitally darkened to "add diversity" to a picture posted on the American version of the school's website.

The crudely photoshopped picture, as well as the original, went viral on social media when one of the school's former students posted the two versions on Twitter. "The photo was originally shared in a French animation studio by a [current] student of the school, and then broadcast on a Facebook group," Kelsi Phụng, who studied at Émile Cohl during the 2011-12 school year, told CNN. "Desiring to preserve [the student's] anonymity, I am responsible for broadcasting the photomontage."

La photo de base est trouvable sur leur twitter en plus, mon dieu pic.twitter.com/HzF9PVUghe — Ameliabrador (@ameliabrador) September 9, 2018

A side-by-side comparison between the two images shows that some students' facial features were darkened to make them appear black. Also, in the manipulated version, two black people were added in the middle of the group.

The institution, which designed the website in English to shore up its reputation as it plans to open a branch in Los Angeles in the next four years, has since apologized for the blunder, blaming the communications company it hired in the US.

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