Fashion fans were surprised to see that the models' knees had been erased on the publication's November cover.
"omfg that Gigi and kendall shoot who did their photoshop they need to be fired," one person tweeted in response.
"Why is photoshop like that allowed? Gigi and Kendall are beautiful the way they are," another added.
Others pointed out that the gaps in Jenner's smile had been removed, leaving the 20-year-old with one big tooth. Hadid's foot had also been altered in a way that made her -- six -- toes look melded together.
"The images of Kendall and Gigi are part of a project by artists Lizzie Fitch and Ryan Trecartin, who are known for their deliberate use of digital technology, combining distortions with makeup and prosthetics," a W spokesperson told BuzzFeed.
Jenner opened up about her career in an accompanying interview released this week. The model, who has walked the runway for Chanel and Balmain, told W she spends "ten months out of the year" working.
"I was, like, ten when I started thinking models were the coolest people in the world," she revealed. "My favorite model when I was ten was Gisele [Bundchen]. I didn't really know what I was talking about, and I think it's the only name I knew."
"I'm working almost every day," the star said. "I think I was raised to be a workaholic, so I think that I knew it was going to happen at some point. I've been working since I was ten years old."
Jenner and her family came to fame on the E! series Keeping Up with the Kardashians, which will return to television Sunday. Hadid is the daughter of former Real Housewives of Beverly Hills star Yolanda Hadid.